efficient coupling and - tum

IMEC 2009, Orlando, 18/11/2009, Miriam Mehl

Efficient Coupling and Flow Simulations

in Partitioned Fluid-Structure Interaction Simulations

Miriam Mehl

Department of Computer Science, TU München


Outline

• spacetrees• flow solver Peano• preCICE• numerical results / examples


Spacetrees

• do not store empty information!!!


Spacetrees

• structured• adaptive• multilevel / hierarchical


Outline



Spacetrees for a Flow Solver

• structuredness low memory requirements

prefined?

u,v,w



• structuredness low memory requirements 2D Peano

p, resrefined?

u,v,w, res,grad(p), ref.crit.

14 bytes

20 bytes



• structuredness low memory requirements 3D Peano

p, resrefined?

u,v,w, res,grad(p), ref.crit.

18 bytes

28 bytes



• standard problem of data intensive applications

Artist: Job Koelewijn



• structuredness high memory access efficiency

Peano order



• Peano solution: use streams and stacks



• Peano solution: use streams and stackscache hitrates (L2) > 99%file stacks no memory restriction



• structuredness dynamical load balancing

0

1 2 3 4

5 6 7 8 17 18 19 20

13 14 15 169 10 11 12



• structurednessdynamical load balancing



• adaptivity less degrees of freedom



• adaptivity moving geometries



• multilevel / hierarchy fast solvers

F-cycle coarse

fine



• multilevel / hierarchy fast solvers

error

after 10 Gauss-Seidel iterations after 1 multigrid iteration



• multilevel / hierarchy multilevel / hierarchical coupling

gf

puut

uuR

g hhhhhh

hh

rr

rrr

rr

−=

∇+∇⋅+∂∂+Δ−= )(1

fluidstructure

g f

multilevelconsistent forces



• multilevel / hierarchy multilevel / hierarchical coupling

work in progress



• multilevel / hierarchy computational steering

fast response

accurate analysis (HPC)

successive refinement



• multilevel / hierarchy computational steering



• flow solver in the PDE framework Peano:

http://www5.in.tum.de/peano/


Outline



preCICE

• coupling tool for partitioned simulations

coupling control + strategy

data mapping

flow solver

structure solver

preC

ICE

preC

ICE


preCICE – Central Mesh

• glue / separator between non-matching grids

• surface triangulation

• CAD interface todo

• Peano geometry interface √


Spacetrees for Surface Coupling

• task: geometrical neighbourhood relations

central mesh

octree

grid point triangle+ projection



• structuredness fast dynamical spacetree• builts up according to queries• apt for moving gemetries



• adaptivity memory & time saving• multilevel / hierarchicy fast algorithms (inheritance)

17.4 128,0005123

14.3 32,0005123

10.18,0005123

2.6 8,0002563

sec# triang.Cart.res.

neighbourhood search measured on a Pentium M 1.6 GHz processor with 2048 kB cache

22.489.6

358.4



• coupling environment preCICEhttp://www5.in.tum.de/wiki/index.php/Software_Developments#preCICE


Outline



Fluid Solver Peano – Navier-Stokes

max. level min. level no dof drag lift6 6 12,486 141.70 15.607 6 14,570 149.30 11.448 6 21,302 137.07 10.46

reference -- -- 136.70 10.53

FSI-CFD 2Re = 100(Turek, Hron 2006)

Source: Tobias Neckel, Bernhard Gatzhammer


Fluid Solver Peano – Lattice Boltzmann

• regular grids √• adaptive grids √

without fluctuations with fluctuations

Source: Philipp Neumann


First Coupling Results with Peano

Source: Bernhard Gatzhammer


Moving Geometries with Peano

Source: Kristof Unterweger


First Coupling Results – Peano+Dummy

Source: Bernhard Gatzhammer


First Coupling Results

Source: Bernhard Gatzhamme/Janos Benk


Summary and Outlook

• Peano– high memory-efficiency √– fully adaptive fixed grids √– multigrid solvers √– consistent forces √– user-driven choice of grid levels √

• preCICE– full partitioned flexibilty √– fast data mapping with spacetrees √


Acknowledgements

• Bernhard Gatzhammer• Tobias Neckel• Tobias Weinzierl• Philipp Neumann• Janos Benk• Kristof Unterweger• Atanas Atanasov


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efficient coupling and - tum

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