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May 29, 2011, 05:06 |
decomposePar change the result?
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#1 |
New Member
Mikael Fuglsang
Join Date: Nov 2010
Posts: 2
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Hi
I'm thying to solve the turbulent flow for a open channel using the LESModel oneEqEddy. I created a rectangular box with wallFunctions at the three fixed walls, rigid lid at the open surface and cyclic conditions at the ends, to simulate a infinitely long channel. The flow is driven by a pressure gradient anded in pimpleFoam UEqn.C tmp<fvVectorMatrix> UEqn ( fvm::ddt(U) + fvm::div(phi, U) + GradPz + turbulence->divDevReff(U) ); dimensionedVector GradPz ( "GradPz", p.dimensions()/dimLength,vector(0.0,0.0,0.0) ); scalar SlopeGradPz ( readScalar(transportProperties.lookup("SlopeGradPz ")) ); The strange thing is that the result changes when I change the the number of processors in the decomposeDict, and that the result of a 100 long channel calculated by 4 processors, gives the same average flow as a 25 long of one processor. The strange thing is that a 100 long channel on 5 processors is the same as a 20 long, but not the same 100 long of 4 processors. The SlopeGradPz is the same for all four cases. My ddtSheme type is steadyState and the end time in both cases are 350 with deltaT of 0.1. How can I make sure that the result is not influenced by the decomposition of the problem? |
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