basic boundary conditions in openfoam v2.4
TRANSCRIPT
Basic Boundary Conditions
in OpenFOAM v2.4
Classification
Steady Time-
varying
Dirichlet
Neumann
Robin Not
Implemented
Periodic
Symmetry
fixedValue uniformFixedValue
fixedGradient uniformFixedGradient
zeroGradient
mixed
cyclic
𝜙 𝒙 = 𝑓 𝒙 𝜙 𝒙, 𝑡 = 𝑓 𝒙, 𝑡
𝜕𝜙
𝜕𝒏𝒙 = 𝑔 𝒙
𝜕𝜙
𝜕𝒏𝒙, 𝑡 = 𝑔 𝒙, 𝑡
𝜕𝜙
𝜕𝒏𝒙 = 0
a𝛼 𝒙 𝜙 𝒙
+𝛽 𝒙𝜕𝜙
𝜕𝒏𝒙 = ℎ 𝒙
cyclicAMI
mixed BC
mixed fixedValue
fixedGradient
=
+ ×
× w
(1-w)
w
fixedValue
fixedGradient
W = 1
W = 0
mixed
symmetryPlane
symmetryPlane or slip?
𝜕𝜙
𝜕𝒏𝒙 = 0
Scalar 𝜙 Vector 𝝓
𝝓 𝒙 ∙ 𝒏 = 0, 𝜕𝝓𝑡
𝜕𝒏𝒙 = 𝟎
symmetryPlane is used on
a single and perfectly flat boundary
slip can be used on curved boundaries
symmetryPlane slip
𝒏
mixed BC is a combination of
fixedValue and fixedGradient BCs
A weighting parameter w (0-1) switches between these types
directionMixed BC
For vector fields, directionMixed BC
is a combination of fixedValue and
fixedGradient BCs
A weighting parameter (tensor) controls which direction these BCs are apply to
1
2𝒏⊗ 𝒏 + 𝒏⊗𝒏 𝑇
w
𝑂3 (Zero matrix)
𝐼3 (Identity matrix) fixedValue
fixedGradient
fixedGradient
fixedValue
Normal direction
Tangential direction
All directions