decay characterization of solutions to dissipative systemsschonbek introduction navier-stokes...
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![Page 1: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/1.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Decay characterization of solutions todissipative systems
César J. Niche 1 and María E. Schonbek 2
1Depto. Mat. Aplicada. UFRJ, Rio de Janeiro - Brazil
2Math. Department. UC Santa Cruz - USA
PaviaMarch 2014
![Page 2: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/2.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
1 IntroductionNavier-StokesNavier-Stokes: decay questionsDecay of solutions to the heat equation
2 Characterization of the initial datumDefinitionsResults
3 Linear Part and decayLinear PartDecay
4 ApplicationsQuasi-Geostrophic equationsApproximation for compressible Navier-StokesComments
![Page 3: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/3.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
1 IntroductionNavier-StokesNavier-Stokes: decay questionsDecay of solutions to the heat equation
2 Characterization of the initial datumDefinitionsResults
3 Linear Part and decayLinear PartDecay
4 ApplicationsQuasi-Geostrophic equationsApproximation for compressible Navier-StokesComments
![Page 4: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/4.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Navier-Stokes equations
Dissipation
We study dissipative fluid equations such as Navier-Stokes
∂tu + (u · ∇) u = −∇p + ∆u
∇ · u = 0
u0(x) = u(x, 0).
u = velocity of homogeneous incompressible fluid in R3
u0 ∈ L2, weak solutions exist (Leray 34).
![Page 5: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/5.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Decay of solutions to the Navier-Stokes equations
Suppose u regular, multiply NS-equation by u + integration⇒
12
ddt
∫R3|u(x, t)|2 dx = −
∫R3|∇u(x, t)|2 dx < 0.
Original question (Leray, Kato): How does the L2-energydecay for weak solutions..
Answer1: (Masuda ’84): if u0 ∈ L2,⇒
‖u(t)‖L2t→∞−−−→ 0.
![Page 6: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/6.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Decay of solutions to the Navier-Stokes equations
Suppose u regular, multiply NS-equation by u + integration⇒
12
ddt
∫R3|u(x, t)|2 dx = −
∫R3|∇u(x, t)|2 dx < 0.
Original question (Leray, Kato): How does the L2-energydecay for weak solutions..
Answer1: (Masuda ’84): if u0 ∈ L2,⇒
‖u(t)‖L2t→∞−−−→ 0.
![Page 7: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/7.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Decay of solutions to the Navier-Stokes equations
Suppose u regular, multiply NS-equation by u + integration⇒
12
ddt
∫R3|u(x, t)|2 dx = −
∫R3|∇u(x, t)|2 dx < 0.
Original question (Leray, Kato): How does the L2-energydecay for weak solutions..
Answer1: (Masuda ’84): if u0 ∈ L2,⇒
‖u(t)‖L2t→∞−−−→ 0.
![Page 8: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/8.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Decay of solutions to the Navier-Stokes equations
More decay results
(M.E. S. ’85-86) If u0 ∈ L1 ∩ L2,⇒
‖u(t)‖L2 ≤ C(1 + t)−34 .
(M.E. S ’86) Decay without a rate : givenr,T, ε > 0,∃u0, with ‖u0‖L2 = r satisfying
‖u(T)‖L2
‖u0‖L2≥ 1− ε.
![Page 9: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/9.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Decay of solutions to the Navier-Stokes equations
More decay results
(M.E. S. ’85-86) If u0 ∈ L1 ∩ L2,⇒
‖u(t)‖L2 ≤ C(1 + t)−34 .
(M.E. S ’86) Decay without a rate : givenr,T, ε > 0,∃u0, with ‖u0‖L2 = r satisfying
‖u(T)‖L2
‖u0‖L2≥ 1− ε.
![Page 10: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/10.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Decay of solutions to the Navier-Stokes equations
(Wiegner ’87) If ‖et∆u0‖L2 ≤ C(1 + t)−12α0 ,⇒
‖u(t)‖L2 ≤ C(1 + t)−12 min{α0,
52}.
(M.E. Schonbek y Wiegner ’96) If ‖et∆u0‖L2 ≤ C(1 + t)−µ
+ more hypothesis and m ∈ N
‖Dmu(t)‖L2 ≤ C(1 + t)−( 12 m+µ).
![Page 11: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/11.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Decay of solutions to the Navier-Stokes equations
(Wiegner ’87) If ‖et∆u0‖L2 ≤ C(1 + t)−12α0 ,⇒
‖u(t)‖L2 ≤ C(1 + t)−12 min{α0,
52}.
(M.E. Schonbek y Wiegner ’96) If ‖et∆u0‖L2 ≤ C(1 + t)−µ
+ more hypothesis and m ∈ N
‖Dmu(t)‖L2 ≤ C(1 + t)−( 12 m+µ).
![Page 12: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/12.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Ideas for the proof
“Behavior of solutions for large time is determined by lowfrequencies of the solutions”.
Use a time depending filter to study the low frequencies.
This is the Fourier Splitting method ( S ’80s).
![Page 13: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/13.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Ideas for the proof
“Behavior of solutions for large time is determined by lowfrequencies of the solutions”.
Use a time depending filter to study the low frequencies.
This is the Fourier Splitting method ( S ’80s).
![Page 14: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/14.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Ideas for the proof
“Behavior of solutions for large time is determined by lowfrequencies of the solutions”.
Use a time depending filter to study the low frequencies.
This is the Fourier Splitting method ( S ’80s).
![Page 15: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/15.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
L2 decay and frequencies at origin
Figure: frequency behavior near origin
![Page 16: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/16.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Heat equation
Heat equation in Rn
ut −∆u = 0
u0(x) = u(x, 0),
well known solution
u(x, t) = Gt ∗ u0(x) =1
(4πt)n2
e−|x|24t ∗ u0(x).
![Page 17: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/17.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Heat equation: exponential decay
Let u0 ∈ L2(Rn) and u0(ξ) = 0, when |ξ| < δ.
⇒
‖u(t)‖2L2 =
∫|ξ|>δ
e−8π|ξ|2t|u0(ξ)|2 dξ
= C e−8πδ2t.
![Page 18: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/18.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Heat equation: exponential decay
Let u0 ∈ L2(Rn) and u0(ξ) = 0, when |ξ| < δ.
⇒
‖u(t)‖2L2 =
∫|ξ|>δ
e−8π|ξ|2t|u0(ξ)|2 dξ
= C e−8πδ2t.
![Page 19: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/19.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Heat equation: slow decay
Recall
12
ddt
∫Rn|u(x, t)|2 dx = −
∫Rn|∇u(x, t)|2 dx < 0,
if ‖∇u(t)‖L2 << 1 ⇒ decay rate becomes slower withsmaller L2 gradients.
![Page 20: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/20.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Heat equation: slow decay
Let B = {v : ‖v‖2 = 1}.
Let uλ0 (x) = λn2 e−π
|λx|22 , then uλ0 (x) ∈ B,
Frequencies and L2 norms of gradients
uλ0 (ξ) =
(2λ
) n2
e−2πλ2 |ξ|2 ‖∇uλ0‖L2 = πλ‖∇u0‖L2
![Page 21: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/21.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Heat equation: slow decay
Let B = {v : ‖v‖2 = 1}.
Let uλ0 (x) = λn2 e−π
|λx|22 , then uλ0 (x) ∈ B,
Frequencies and L2 norms of gradients
uλ0 (ξ) =
(2λ
) n2
e−2πλ2 |ξ|2 ‖∇uλ0‖L2 = πλ‖∇u0‖L2
![Page 22: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/22.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Heat equation: slow decay
Let B = {v : ‖v‖2 = 1}.
Let uλ0 (x) = λn2 e−π
|λx|22 , then uλ0 (x) ∈ B,
Frequencies and L2 norms of gradients
uλ0 (ξ) =
(2λ
) n2
e−2πλ2 |ξ|2 ‖∇uλ0‖L2 = πλ‖∇u0‖L2
![Page 23: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/23.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Heat equation slow decay
For some fixed t > 0 decay for solutions with data uλ0 ∈ Bwill not be uniform :
‖uλ(t)‖2L2
‖uλ0‖2L2
=1
1 + 4λ2tλ→0−−−→ 1.
There exist solution to the heat equation with data in L2(Rn)decaying arbitrarily slowly.
Theorem
Given r,T, ε > 0 ⇒ ∃u0 with ‖u0‖L2 = r so that
‖u(T)‖L2
‖u0‖L2≥ 1− ε.
![Page 24: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/24.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Heat equation slow decay
For some fixed t > 0 decay for solutions with data uλ0 ∈ Bwill not be uniform :
‖uλ(t)‖2L2
‖uλ0‖2L2
=1
1 + 4λ2tλ→0−−−→ 1.
There exist solution to the heat equation with data in L2(Rn)decaying arbitrarily slowly.
Theorem
Given r,T, ε > 0 ⇒ ∃u0 with ‖u0‖L2 = r so that
‖u(T)‖L2
‖u0‖L2≥ 1− ε.
![Page 25: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/25.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Heat equation: Fourier Splitting
The behavior of large times is determined by the lowfrequencies of the solution.
Filter: “et∆ ≤ C′′ yields “t|ξ|2 ≤ C′′ ⇒
B(t) ={ξ : |ξ|2 ≤ C
t + 1
}.
![Page 26: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/26.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Heat equation: Fourier Splitting
The behavior of large times is determined by the lowfrequencies of the solution.
Filter: “et∆ ≤ C′′ yields “t|ξ|2 ≤ C′′ ⇒
B(t) ={ξ : |ξ|2 ≤ C
t + 1
}.
![Page 27: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/27.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Fourier Splitting : old idea (86)
ddt‖u(t)‖2
L2 ≤ −C‖∇u(t)‖2L2
knowledge of bounds for u0(ξ), |ξ| � 1
ddt‖u(t)‖2
L2 = −2‖∇u(t)‖2L2
= −2∫
B(t)∪B(t)c|ξ|2|u(t)|2 dξ
≤ −2∫
B(t)|ξ|2|u(t)|2 dξ − C
1 + t
∫B(t)c|u(t)|2 dξ
≤ C1 + t
∫B(t)|u(t)|2 dξ − C
1 + t
∫Rn|u(t)|2 dξ.
![Page 28: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/28.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Fourier Splitting : old idea (86)
ddt‖u(t)‖2
L2 ≤ −C‖∇u(t)‖2L2
knowledge of bounds for u0(ξ), |ξ| � 1
ddt‖u(t)‖2
L2 = −2‖∇u(t)‖2L2
= −2∫
B(t)∪B(t)c|ξ|2|u(t)|2 dξ
≤ −2∫
B(t)|ξ|2|u(t)|2 dξ − C
1 + t
∫B(t)c|u(t)|2 dξ
≤ C1 + t
∫B(t)|u(t)|2 dξ − C
1 + t
∫Rn|u(t)|2 dξ.
![Page 29: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/29.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Fourier Splitting
ddt
((t + 1)n‖u(t)‖2
L2
)≤ C(t + 1)n−1
∫B(t)|u(ξ, t)|2 dξ.
If u0 ∈ L1(Rn), and |u0(ξ)| ≤ C, for |ξ| � 1 ⇒
‖u(t)‖L2(Rn) ≤ C(t + 1)−n4 .
![Page 30: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/30.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Fourier Splitting
ddt
((t + 1)n‖u(t)‖2
L2
)≤ C(t + 1)n−1
∫B(t)|u(ξ, t)|2 dξ.
If u0 ∈ L1(Rn), and |u0(ξ)| ≤ C, for |ξ| � 1 ⇒
‖u(t)‖L2(Rn) ≤ C(t + 1)−n4 .
![Page 31: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/31.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Fourier Splitting
ddt
((t + 1)n‖u(t)‖2
L2
)≤ C(t + 1)n−1
∫B(t)|u(ξ, t)|2 dξ.
If u0 ∈ L1(Rn), and |u0(ξ)| ≤ C, for |ξ| � 1 ⇒
‖u(t)‖L2(Rn) ≤ C(t + 1)−n4 .
![Page 32: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/32.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Fourier Splitting
Fourier Splitting also works given info on FT near origin +
ddt‖u(t)‖2
L2(Rn) ≤ −C∫Rn|ξ|2α|u(ξ, t)|2 dξ.
Works for Parabolic conservation laws, Navier-Stokes,MHD, sistemas KdV-Burgers, dissipative QG, dissipativeCamassa-Holm, · · · .If solution stay in L1 can use Cordoba-Cordoba methods.(generally not good for derivatives)
![Page 33: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/33.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Fourier Splitting
Fourier Splitting also works given info on FT near origin +
ddt‖u(t)‖2
L2(Rn) ≤ −C∫Rn|ξ|2α|u(ξ, t)|2 dξ.
Works for Parabolic conservation laws, Navier-Stokes,MHD, sistemas KdV-Burgers, dissipative QG, dissipativeCamassa-Holm, · · · .If solution stay in L1 can use Cordoba-Cordoba methods.(generally not good for derivatives)
![Page 34: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/34.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Fourier Splitting
Fourier Splitting also works given info on FT near origin +
ddt‖u(t)‖2
L2(Rn) ≤ −C∫Rn|ξ|2α|u(ξ, t)|2 dξ.
Works for Parabolic conservation laws, Navier-Stokes,MHD, sistemas KdV-Burgers, dissipative QG, dissipativeCamassa-Holm, · · · .If solution stay in L1 can use Cordoba-Cordoba methods.(generally not good for derivatives)
![Page 35: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/35.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Ingredients of ideas for Lower and Upper bounds ofdecay
Knowledge of behavior of low frequencies of the solutions.
Behavior of solution to the linear underlying equation.
Influence of the non linear part.
![Page 36: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/36.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Ingredients of ideas for Lower and Upper bounds ofdecay
Knowledge of behavior of low frequencies of the solutions.
Behavior of solution to the linear underlying equation.
Influence of the non linear part.
![Page 37: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/37.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Ingredients of ideas for Lower and Upper bounds ofdecay
Knowledge of behavior of low frequencies of the solutions.
Behavior of solution to the linear underlying equation.
Influence of the non linear part.
![Page 38: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/38.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Objetives
Objetive: give a good characterization of the (L2, Sobolev)decay of solutions to dissipative equations
characterization of the initial datum,study of the linear part,study of the nonlinear part.study of difference of linear and nonlinear solutions
![Page 39: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/39.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
1 IntroductionNavier-StokesNavier-Stokes: decay questionsDecay of solutions to the heat equation
2 Characterization of the initial datumDefinitionsResults
3 Linear Part and decayLinear PartDecay
4 ApplicationsQuasi-Geostrophic equationsApproximation for compressible Navier-StokesComments
![Page 40: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/40.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Decay indicator
Definition (Bjorland - MES ’09, Niche - MES ’13)
Let u0 ∈ L2(Rn), r ∈(− n
2 ,∞). The decay indicator of u0 is
defined by
Pr(u0) = limρ→0
ρ−2r−n∫
B(ρ)|u0(ξ)|2 dξ
where B(ρ) = {ξ : |ξ| ≤ ρ}.
The decay indicator compares |u0| with f (ξ) = |ξ|r at ξ = 0.
![Page 41: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/41.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Decay character
Definition (Bjorland - MES ’09, Niche - MES ’13)
Let u0 ∈ L2(Rn). The decay character of u0 is r∗ = r∗(u0), is theunique r ∈
(− n
2 ,∞)
so that 0 < Pr(u0) <∞, if this numberexists. If it does not exist then
r∗(u0) =
{− n
2 , if Pr(u0) =∞, for all r ∈(−n
2 ,∞)
∞, if Pr(u0) = 0, for all r ∈(− n
2 ,∞).
![Page 42: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/42.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
s-decay indicator
Definition (CJN - MES ’13)
Let u0 ∈ L2(Rn), s > 0, r ∈(−n
2 + s,∞). The s-decay indicator
de Λsu0 is defined as
Psr(u0) = lim
ρ→0ρ−2r−n
∫B(ρ)|ξ|2s|u0(ξ)|2 dξ
where B(ρ) = {ξ : |ξ| ≤ ρ}.
The s-decay indicator compares |Λsu0| with f (ξ) = |ξ|r atξ = 0.
![Page 43: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/43.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
s-decay character
Definition (CJN - MES ’13)
The s-decay character of Λsu0, is the unique r∗s = r∗s (u0), withr ∈
(−n
2 + s,∞)
tso that 0 < Psr(u0) <∞, provided this number
exists. If it does not exist the
r∗s (u0) =
{∞, if Pr(u0) = 0, for all q ∈
(−n
2 + s,∞)
− n2 + s, if Pr(u0) =∞, for all q ∈
(−n
2 + s,∞).
![Page 44: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/44.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Remark
If u0 ∈ Lp(Rn) ∩ L2(Rn), 1 ≤ p ≤ 2
The definition of decay character⇒ r∗(u0) = −n(
1− 1p
).
If u0 ∈ L1(Rn) ∩ L2(Rn)⇒ r∗(u0) = 0
If u0 ∈ L2(Rn) but u0 /∈ Lp(Rn), for any1 ≤ p < 2 ⇒ r∗(u0) = − n
2 .
![Page 45: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/45.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Remark
If u0 ∈ Lp(Rn) ∩ L2(Rn), 1 ≤ p ≤ 2
The definition of decay character⇒ r∗(u0) = −n(
1− 1p
).
If u0 ∈ L1(Rn) ∩ L2(Rn)⇒ r∗(u0) = 0
If u0 ∈ L2(Rn) but u0 /∈ Lp(Rn), for any1 ≤ p < 2 ⇒ r∗(u0) = − n
2 .
![Page 46: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/46.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Remark
If u0 ∈ Lp(Rn) ∩ L2(Rn), 1 ≤ p ≤ 2
The definition of decay character⇒ r∗(u0) = −n(
1− 1p
).
If u0 ∈ L1(Rn) ∩ L2(Rn)⇒ r∗(u0) = 0
If u0 ∈ L2(Rn) but u0 /∈ Lp(Rn), for any1 ≤ p < 2 ⇒ r∗(u0) = − n
2 .
![Page 47: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/47.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Remark
If u0 ∈ Lp(Rn) ∩ L2(Rn), 1 ≤ p ≤ 2
The definition of decay character⇒ r∗(u0) = −n(
1− 1p
).
If u0 ∈ L1(Rn) ∩ L2(Rn)⇒ r∗(u0) = 0
If u0 ∈ L2(Rn) but u0 /∈ Lp(Rn), for any1 ≤ p < 2 ⇒ r∗(u0) = − n
2 .
![Page 48: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/48.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Relation between the decay character and thes-decay character
Theorem (CJN - MES ’13)
Let u0 ∈ Hs(Rn), s > 0.
1 If −n2 < r∗(u0) <∞ then −n
2 + s < r∗s (u0) <∞ andr∗s (u0) = s + r∗(u0).
2 r∗s (u0) =∞ if an only if r∗(u0) =∞.
3 r∗(u0) = −n2 if and only if r∗s (u0) = r∗(u0) + s = −n
2 + s.
![Page 49: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/49.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
1 IntroductionNavier-StokesNavier-Stokes: decay questionsDecay of solutions to the heat equation
2 Characterization of the initial datumDefinitionsResults
3 Linear Part and decayLinear PartDecay
4 ApplicationsQuasi-Geostrophic equationsApproximation for compressible Navier-StokesComments
![Page 50: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/50.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
How does the linear part need to behave ?
Recall Fourier Splitting works if we have info of frequencies nearthe origin and
ddt‖u(t)‖2
L2(Rn) ≤ −C∫Rn|ξ|2α|u(ξ, t)|2 dξ.
![Page 51: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/51.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Behavior of linear part?
Let L : Xn →(L2(Rn)
)n be a pseudodifferential operator , on X aHilbert space,so that:
The symbolM(ξ) of L is such that
M(ξ) = P−1(ξ)D(ξ)P(ξ), ξ − a.e.
P(ξ) ∈ O(n) and D(ξ) = −ci|ξ|2αδij, for ci > c > 0 and0 < α ≤ 1. for constants a, b > 0, with 0 < α ≤ 1.
⇒ linear equation
vt = Lv. (1)
![Page 52: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/52.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Behavior of linear part?
Let L : Xn →(L2(Rn)
)n be a pseudodifferential operator , on X aHilbert space,so that:
The symbolM(ξ) of L is such that
M(ξ) = P−1(ξ)D(ξ)P(ξ), ξ − a.e.
P(ξ) ∈ O(n) and D(ξ) = −ci|ξ|2αδij, for ci > c > 0 and0 < α ≤ 1. for constants a, b > 0, with 0 < α ≤ 1.
⇒ linear equation
vt = Lv. (1)
![Page 53: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/53.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Behavior of linear part?
Let L : Xn →(L2(Rn)
)n be a pseudodifferential operator , on X aHilbert space,so that:
The symbolM(ξ) of L is such that
M(ξ) = P−1(ξ)D(ξ)P(ξ), ξ − a.e.
P(ξ) ∈ O(n) and D(ξ) = −ci|ξ|2αδij, for ci > c > 0 and0 < α ≤ 1. for constants a, b > 0, with 0 < α ≤ 1.
⇒ linear equation
vt = Lv. (1)
![Page 54: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/54.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Behavior of linear part?
Given the linear equation
∂tv = Lv
haciendo el producto en L2 con v y usando las propiedades de Lllegamos a que podemos usar Fourier Splitting, i.e.
ddt‖v(t)‖2
L2(Rn) ≤ −C∫Rn|ξ|2α |v(ξ, t)|2 dξ.
![Page 55: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/55.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Example: Compressible approximation to Stokes
Example
Compressible approximation to the Stokes system in R3 (Temam)
ut = Lu = ∆u +1ε∇div u, ε > 0. (2)
Symbol (M(ξ))ij = −|ξ|2δij − 1ε ξiξj, with
D(ξ) = diag(−|ξ|2,−|ξ|2,−(1 + 1
ε
)|ξ|2) and
P(ξ) =
−ξ2√ξ2
1+ξ22
−ξ1ξ3√1−ξ2
3ξ1
ξ1√ξ2
1+ξ22
−ξ2ξ3√1−ξ2
3ξ2
0 1−ξ23√
1−ξ23
ξ3
,
![Page 56: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/56.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Example: Compressible approximation to Stokes
Example
Compressible approximation to the Stokes system in R3 (Temam)
ut = Lu = ∆u +1ε∇div u, ε > 0. (2)
Symbol (M(ξ))ij = −|ξ|2δij − 1ε ξiξj, with
D(ξ) = diag(−|ξ|2,−|ξ|2,−(1 + 1
ε
)|ξ|2) and
P(ξ) =
−ξ2√ξ2
1+ξ22
−ξ1ξ3√1−ξ2
3ξ1
ξ1√ξ2
1+ξ22
−ξ2ξ3√1−ξ2
3ξ2
0 1−ξ23√
1−ξ23
ξ3
,
![Page 57: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/57.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Example continuation
decay Kernel
(etM(ξ)
)ij
= e−t|ξ|2δij −ξiξj
|ξ|2(
e−t|ξ|2 − e−(1+ 1ε)t|ξ|2
), (3)
![Page 58: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/58.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Results
Theorem (CJN - MES ’13)
Let v0 ∈ L2(Rn) have decay character r∗(v0) = r∗. Let v(t) be asolution to the linear equation with data v0. Then:
if −n2 < r∗ <∞, there exist constants C1,C2 > 0 such that
C1(1 + t)−1α( n
2 +r∗) ≤ ‖v(t)‖2L2 ≤ C2(1 + t)−
1α( n
2 +r∗);
![Page 59: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/59.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Theorem
if r∗ = −n2 , there exists C > 0 such that
‖v(t)‖2L2 ≥ C(1 + t)−ε, ∀ε > 0,
i.e. the decay of ‖v(t)‖2L2 is slower than any uniform
algebraic rate;
if r∗ =∞, there exists C > 0 such that
‖v(t)‖2L2 ≤ C(1 + t)−m, ∀m > 0,
i.e. the decay of ‖v(t)‖L2 is faster than any algebraic rate.
![Page 60: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/60.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Theorem (CJN - MES ’13)
Let v0 ∈ Hs(Rn), s > 0 have decay character r∗s = r∗s (v0). Then
1 if −n2 ≤ r∗ <∞, there exist constants C1,C2 > 0 such that
C1(1 + t)−1α( n
2 +r∗+s) ≤ ‖v(t)‖2Hs ≤ C2(1 + t)−
1α( n
2 +r∗+s);
2 if r∗ =∞, then
‖v(t)‖2Hs ≤ C(1 + t)−r, ∀r > 0,
i.e. the decay of ‖v(t)‖Hs is faster than any algebraic rate.
![Page 61: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/61.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
1 IntroductionNavier-StokesNavier-Stokes: decay questionsDecay of solutions to the heat equation
2 Characterization of the initial datumDefinitionsResults
3 Linear Part and decayLinear PartDecay
4 ApplicationsQuasi-Geostrophic equationsApproximation for compressible Navier-StokesComments
![Page 62: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/62.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Quasi-Geostrophic equations
Dissipative Quasi-Geostrophic equations
θt + u · ∇θ + (−∆)α2 θ = 0, 0 < α ≤ 2
where θ is the temperature of a fluid in R2, and
u = R⊥θ = (−R2θ,R1θ)
where Ri is the Riesz transform in xi.
![Page 63: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/63.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Results for QG
Theorem (CJN - MES ’13)
Let θ0 ∈ L2(R2), let r∗ = r∗(θ0),−1 < r∗ <∞, and 0 < α ≤ 1.Let θ be a weak solution to QGE with data θ0. Then:
1 If r∗ ≤ 1− α, then
‖θ(t)‖2L2 ≤ C(t + 1)−
1α
(1+r∗);
2 if r∗ ≥ 1− α, then
‖θ(t)‖2L2 ≤ C(t + 1)−
1α
(2−α).
![Page 64: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/64.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Results QG
Theorem (CJN - MES ’13)
Let 12 < α ≤ 1, α ≤ s and θ0 ∈ Hs(R2). For r∗ = r∗(θ0) the
solutions to QGE satisfy
1 if r∗ ≤ 1− α, then
‖θ(t)‖2Hs ≤ C(t + 1)−
1α
(s+1+r∗);
2 if r∗ ≥ 1− α, then
‖θ(t)‖2Hs ≤ C(t + 1)−
1α
(s+2−α).
![Page 65: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/65.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Nonlinear minus Linear QG
Decay of the nonlinear part of QGE w(t) = θ(t)−Θ(t).
Theorem (CJN - MES ’13)
Let 0 < α ≤ 1, θ0 ∈ L2(R2), r∗ = r∗(θ0). Then
1 if −1 < r∗ ≤ 1− α and 1+r∗α ≥ 1, we have
‖θ(t)−Θ(t)‖2L2 ≤ C(1 + t)−
1α
min{2,2−α+r∗};
2 if −1 < r∗ ≤ 1− α and 1+r∗α < 1, we have
‖θ(t)−Θ(t)‖2L2 ≤ C(1 + t)−
1α
(2−α+r∗);
3 if r∗ ≥ 1− α, then
‖θ(t)−Θ(t)‖2L2 ≤ C(1 + t)−
1α
min{3−2α,2}.
![Page 66: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/66.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Nonlinear minus Linear QG
Decay of the nonlinear part of QGE w(t) = θ(t)−Θ(t).
Theorem (CJN - MES ’13)
Let 0 < α ≤ 1, θ0 ∈ L2(R2), r∗ = r∗(θ0). Then
1 if −1 < r∗ ≤ 1− α and 1+r∗α ≥ 1, we have
‖θ(t)−Θ(t)‖2L2 ≤ C(1 + t)−
1α
min{2,2−α+r∗};
2 if −1 < r∗ ≤ 1− α and 1+r∗α < 1, we have
‖θ(t)−Θ(t)‖2L2 ≤ C(1 + t)−
1α
(2−α+r∗);
3 if r∗ ≥ 1− α, then
‖θ(t)−Θ(t)‖2L2 ≤ C(1 + t)−
1α
min{3−2α,2}.
![Page 67: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/67.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Lower Bounds QG
Theorem (CJN - MES ’13)
Let 0 < α ≤ 1, θ0 ∈ L2(R2), r∗ = r∗(θ0). Then:
1 if r∗ ≥ 1− α, we have
‖θ(t)‖2L2 ≥ C(1 + t)−
1α
(2−α);
2 if r∗ ≤ 1− α, we have
‖θ(t)‖2L2 ≥ C(1 + t)−
1α
(1+r∗).
![Page 68: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/68.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Lower Bounds QG
Theorem (CJN - MES ’13)
Let 0 < α ≤ 1, θ0 ∈ L2(R2), r∗ = r∗(θ0). Then:
1 if r∗ ≥ 1− α, we have
‖θ(t)‖2L2 ≥ C(1 + t)−
1α
(2−α);
2 if r∗ ≤ 1− α, we have
‖θ(t)‖2L2 ≥ C(1 + t)−
1α
(1+r∗).
![Page 69: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/69.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Approximation for compressible Navier-Stokes
For Navier-Stokes, the presión p is a non local function of u,⇒ problems for numerical studies
(Temam ’68) Penalization method:
∇ · u = −εp
stabilize with a term of the form 12(div u) u.
![Page 70: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/70.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Approximation for compressible Navier-Stokes
For Navier-Stokes, the presión p is a non local function of u,⇒ problems for numerical studies
(Temam ’68) Penalization method:
∇ · u = −εp
stabilize with a term of the form 12(div u) u.
![Page 71: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/71.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Compressible Approximation
We have
uεt + (uε · ∇) uε +12
(div uε) uε = ∆uε +1ε∇div uε,
uε0(x) = uε(x, 0).
Results: Temam ’68, Brefort ’88, Plechác and Šverák ’03,Rusin ’12, + Numerical results.
![Page 72: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/72.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Compressible Approximation
We have
uεt + (uε · ∇) uε +12
(div uε) uε = ∆uε +1ε∇div uε,
uε0(x) = uε(x, 0).
Results: Temam ’68, Brefort ’88, Plechác and Šverák ’03,Rusin ’12, + Numerical results.
![Page 73: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/73.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Linear part, non linear term
Linear part L works with our methods
ut = Lu = ∆u +1ε∇ · div u = 0,
(Mε(ξ, t))kl = e−t|ξ|2δkl −ξkξl
|ξ|2(
e−t|ξ|2 − e−(1+ 1ε)t|ξ|2
).
Non linear part similar to NS
(u · ∇) u +12
(div u) u = ∇ (u⊗ u)− 12
(div u) u.
Compressible part no problem since∫R3
u(u · ∇)u dx = −12
∫R3|u|2div u dx.
![Page 74: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/74.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Linear part, non linear term
Linear part L works with our methods
ut = Lu = ∆u +1ε∇ · div u = 0,
(Mε(ξ, t))kl = e−t|ξ|2δkl −ξkξl
|ξ|2(
e−t|ξ|2 − e−(1+ 1ε)t|ξ|2
).
Non linear part similar to NS
(u · ∇) u +12
(div u) u = ∇ (u⊗ u)− 12
(div u) u.
Compressible part no problem since∫R3
u(u · ∇)u dx = −12
∫R3|u|2div u dx.
![Page 75: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/75.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Linear part, non linear term
Linear part L works with our methods
ut = Lu = ∆u +1ε∇ · div u = 0,
(Mε(ξ, t))kl = e−t|ξ|2δkl −ξkξl
|ξ|2(
e−t|ξ|2 − e−(1+ 1ε)t|ξ|2
).
Non linear part similar to NS
(u · ∇) u +12
(div u) u = ∇ (u⊗ u)− 12
(div u) u.
Compressible part no problem since∫R3
u(u · ∇)u dx = −12
∫R3|u|2div u dx.
![Page 76: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/76.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Results
Theorem (C.J.N. - M.E.S. ’13)
Let uε0 ∈ L2(R3), r∗ = r∗(uε0), ε > 0. Then for a weak solution uε
to the compressible approximation to NS we have that:
1 if −32 < r∗ ≤ 1
4 , then
‖uε(t)‖2L2 ≤ C(1 + t)−(r∗+ 3
2 );
2 if r∗ > 14 , then
‖uε(t)‖2L2 ≤ C(1 + t)−
74 ;
![Page 77: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/77.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Theorem (C.J.N. - M.E.S. ’13)
Let u0 ∈ Hr(R3), r ≥ 1, r∗ = r∗(u0). Then, for 1 ≤ s ≤ r we havethat
‖u(t)‖Hs ≤ C(1 + t)−12 (s+min{ 3
2 ,r∗+ 3
2}).
![Page 78: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/78.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Linear minus nonlinear
Theorem (C.J.N. - M.E.S. ’13)
Let uε0 ∈ L2(R3), r∗ = r∗(u0). Then for compressible NS
‖uε(t)− u(t)‖2L2 ≤ C(1 + t)−
74 .
lower bounds
Will follow by a triangle inequality and estimates of linear partand difference between linear and non linear.
![Page 79: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/79.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Linear minus nonlinear
Theorem (C.J.N. - M.E.S. ’13)
Let uε0 ∈ L2(R3), r∗ = r∗(u0). Then for compressible NS
‖uε(t)− u(t)‖2L2 ≤ C(1 + t)−
74 .
lower bounds
Will follow by a triangle inequality and estimates of linear partand difference between linear and non linear.
![Page 80: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/80.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Commments
Decay character classifies data for which decay is given bythe linear part and those where the nonlinear part has afundamental role.
Gives a sharp division for upper and lower decay
![Page 81: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/81.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Commments
Decay character classifies data for which decay is given bythe linear part and those where the nonlinear part has afundamental role.
Gives a sharp division for upper and lower decay
![Page 82: Decay characterization of solutions to dissipative systemsSchonbek Introduction Navier-Stokes Navier-Stokes: decay questions Decay of solutions to the heat equation Characterization](https://reader036.vdocuments.mx/reader036/viewer/2022071607/61449575b5d1170afb43f7fd/html5/thumbnails/82.jpg)
Decay charac-terization ofsolutions todissipativesystems
C. J. Nicheand M. E.Schonbek
IntroductionNavier-Stokes
Navier-Stokes:decay questions
Decay of solutions tothe heat equation
Characterizationof the initialdatumDefinitions
Results
Linear Partand decayLinear Part
Decay
ApplicationsQuasi-Geostrophicequations
Approximation forcompressibleNavier-Stokes
Comments
Thank you!