turbulence and computing: beauty and the beast - assistant professor gianluca iaccarino

Beauty & the BeastTurbulence and Computing

Gianluca IaccarinoJoe W. Nichols & John Axerio-CiliesMechanical Engineering DepartmentCenter for Turbulence Research, Stanford University

Monday, July 23, 12

Turbulence...the “beauty”

Monday, July 23, 12

The word turbulence (from the latin word turbulentia) originally refers to the disorderly motion of a crowd (turba). In the Middle Ages it was frequently used to mean just "trouble", a word which derives from it.

Its scientific usage refers to irregular and seemingly chaotic motion of a fluid.


Monday, July 23, 12

Monday, July 23, 12

Composition VIWassily Kandinsky (1913)

Monday, July 23, 12




Monday, July 23, 12




But chaos/randomness does not completely illustrate the nature of flow turbulence. There is structure in the chaos!

Monday, July 23, 12

Monday, July 23, 12

Starry NightVincent van Gogh (1889)

Monday, July 23, 12





Monday, July 23, 12





Another important characteristic of turbulence is the presence of multiple scales - small eddies and large eddies

Monday, July 23, 12

much thinner than a human hair

Monday, July 23, 12

Great WaveKatsushika Hokusai (ca 1700)

Monday, July 23, 12






Monday, July 23, 12






The inherent beauty of turbulent motion attracts artists, but it is its inherent complexity and ubiquitous presence that interests physicists, mathematicians and engineers

Monday, July 23, 12

Over five centuries ago Leonardo was probably the first to use the word turbulence (in Italian turbolenza) with its modern meaning and to observe the slow decay of eddies formed behind the pillars of a bridge.

Studying Turbulence

Monday, July 23, 12

Leonardo da Vinci, Codex Atlanticus (ca 1500)

Studying Turbulence

Doue la turbolenza dellacqua si generaDoue la turbolenza dellacua si mantiene plughoDoue la turbolenza dellacqua siriposa

Monday, July 23, 12



Studying Turbulence


Monday, July 23, 12



Where is the turbulence in the water generated?Where does the turbulence in the water persist for long time?Where does the turbulence in the water come to rest?

Studying Turbulence


Monday, July 23, 12

The physics of turbulence has been studied extensively. using experiments. Euler, Navier, Stokes, and later Taylor, Kolmogorov and many others built the theoretical & mathematical foundations

Studying Turbulence

Leonhard Euler1700s

George Gabriel Stokes1800s

Andrei Kolmogorov1900s

Geoffrey Taylor1900s

Monday, July 23, 12

Ener

gy

Eddy Size

Energy spectrum

Monday, July 23, 12

Kolmogorov Theory -5/3

Ener

gy

Eddy Size

Dissipation into heat

Energy spectrum

Monday, July 23, 12


Ener

gy

Eddy Size


Where is the turbulence in the water generated?

Energy spectrum

Monday, July 23, 12


Where does the turbulence in the water come to rest?

Ener

gy

Eddy Size



Energy spectrum

Monday, July 23, 12



Where does the turbulence in the water come to rest?

Ener

gy

Eddy Size


Energy spectrum

Monday, July 23, 12

Center for Turbulence Research

Prof. William C. ReynoldsProf. Joel H. FerzigerProf. Parviz Moin

1987Monday, July 23, 12

Computer Simulations @ CTR

1970 1980 1990 2000 2010

Monday, July 23, 12


1970 1980 1990 2000 2010

Turbulent Flow in a Channel

64 CPUs, 15Mflops, $33M (1972)

Illiac IV

Monday, July 23, 12


1970 1980 1990 2000 2010

16CPUs, 1Gflops, $5M (1988)

Cray YMP

Complex Flow

Monday, July 23, 12

1970 1980 1990 2000 2010

8KCPUs, 5Tflops, $10M (2000)

ASCI White/IBM

Turbulent Flames


Monday, July 23, 12

100KCPUs, 200Tflops, $70M (2005)

BGL-P


1970 1980 1990 2000 2010

End-to-End Aircraft Jet Engine

Monday, July 23, 12

BGL-P

Computing Power

100KCPUs, 200Tflops, $70M (2005)

BGL-P

64 CPUs, 15Mflops, $33M (1972)

Illiac IV

Monday, July 23, 12

BGL-P

Computing Power

100KCPUs, 200Tflops, $70M (2005)

BGL-P

64 CPUs, 15Mflops, $33M (1972)

Illiac IV

1CPU, 36Mflops, $200 (2010)

iphone 4

Monday, July 23, 12

BGL-P

Computing Power

100KCPUs, 200Tflops, $70M (2005)

BGL-P

64 CPUs, 15Mflops, $33M (1972)

Illiac IV

1CPU, 36Mflops, $200 (2010)

iphone 4

sequoia

1.57MCPUs, 16.2Pflops, $? (2012)

Monday, July 23, 12

Quieting A JetJoe Nichols

Slow Down a Formula 1 CarJohn Axerio Cilies

A New Planet in 7 DaysGianluca Iaccarino

Monday, July 23, 12

A Project sponsored by Toyota Motor Corporation

Motor Sport Division

Slow Down a Formula 1 CarJohn Axerio Cilies

Monday, July 23, 12



Monday, July 23, 12



Brake Cooling...

Monday, July 23, 12

• Brake pads are air cooled and temperature is controlled• Flow through the tire has an impact on the wake dynamics

Flowin

Flow out

Monday, July 23, 12

Monday, July 23, 12

Section view looking vertically upwards from contact patch

Through-‐Hub Flow Passages

Monday, July 23, 12

Impact of Through-‐Hub Flow

CI CII

A BA

D

Monday, July 23, 12


CI CII

CIII

A BA

D

A B

Monday, July 23, 12


CI CII

CIII CIV

A BA

D

AA B

Monday, July 23, 12

12% decrease in drag with op3mal choice of fairing!

Experimental ValidaBon of Through-‐Hub Flow

Monday, July 23, 12

Brake Cooling Efficiency

Dra

g

Baseline Design

Monday, July 23, 12


Dra

g

Design with Maximum Cooling

Monday, July 23, 12


Dra

g

Design with Minimum Drag

Monday, July 23, 12


Dra

g

Optimal Design

Monday, July 23, 12

Design using Computations

Monday, July 23, 12

Quieting A JetJoe Nichols

Monday, July 23, 12

Monday, July 23, 12

Rectangular nozzles

Baseline (NA2Z)

Design taken from the “Extensible Rectangular Nozzle Model System” (Frate & Bridges, 2011)

2:1 aspect ra3o, matching experiment precisely

Chevron (NA2C3)

Monday, July 23, 12

Flow development (Baseline)

Preferen7al spreading along minor axis (Zaman, 1996)Monday, July 23, 12

Flow development (Chevrons)

Monday, July 23, 12

Typical supercomputer usage

One liJle square = 128 processors

Monday, July 23, 12

Full system run (163,840 cores)

Monday, July 23, 12

Flow and noise visualizaBon

Baseline (NA2Z) Chevrons (NA2C3)

FWH

LES

FWH

LES

Monday, July 23, 12

Effect of chevronsUpstream Downstream

Chevrons have two (good) effects on noise:

1.Reduc3on of shock-‐associated noise (upstream)

2.Reduc3on of turbulent mixing noise (downstream)

baselinechevrons

baselinechevrons

Monday, July 23, 12

a new planet in 7 DaysAlan Wray, Javier Jimenez, Parviz Moin, Ali Mani, Lee Shunn, Frank Ham, Gianluca Iaccarino

Monday, July 23, 12

BlueGene/L

• DOE/IBM supercomputer at LLNL• Installation Year: 2005 • #1 on Top 500 list: 280 TFLOPS• Theoretical peak: 370 TFLOPS• Compute nodes: 65536 (131072 CPUs)• I/O nodes: 1024• Memory: 32768 GB

Monday, July 23, 12

Keplerian turbulence

• Protoplanetary disks need to be turbulent to form planets• Simplest model is rotating, sheared box of

turbulence

Ωx1

x2

x3

Monday, July 23, 12

Computations

Simulations• Grid size: 8192x2048x2048 ~ 34 billion grid points• Ran on 65536 CPUs (half of the machine)• 10-20 Mhours/CPU• FFT transforms require large data (full volume)

communication multiple times per time-step

Data processing• Each saved data field: 384 GB• Inverse FFT on entire dataset must be performed to visualize solution in physical space

Monday, July 23, 12

Range of scales

Monday, July 23, 12

Energy spectrum

Low-Ro (fast rotation)

not all eddies are dying!

Monday, July 23, 12

Conclusions

• 7 days on BGL and still no planet• Now we know what to look for and where

Monday, July 23, 12

Thank You Turbulence & ComputingBeauty and the Beast

center for turbulence researchParviz Moin

Gianluca IaccarinoJoe. W. Nichols

John Axerio-Cilies Frank Ham

Heinz PitschMarcus Herrmann

Monday, July 23, 12

turbulence and computing: beauty and the beast - assistant professor gianluca iaccarino

Technology