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April 8, 2018, 02:30 |
Unable to capture back flow
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#1 |
New Member
Vachan Potluri
Join Date: Jul 2017
Posts: 29
Rep Power: 9 |
Hello everyone,
I am trying to simulate flow over 2D hill as shown here from ERCOFTAC database using pimpleFoam and kEpsilon turbulence model. I am using openfoam version 4.1. For the inlet at x=-2a (x=0 is the hill top location, 2a is the hill width), I am using data from the above website as the boundary condition. I am using standard boundary conditions for the wall and outlet. I am unable to capture back flow downstream of the hill. Added to that, my y-direction velocity, V, is not matching with the experiment data at all far downstream (figure attached). My residuals in the last iteration are: Code:
Courant Number mean: 0.163516 max: 0.295207 deltaT = 0.000806452 Time = 4 PIMPLE: iteration 1 smoothSolver: Solving for Ux, Initial residual = 6.5802e-06, Final residual = 1.95255e-07, No Iterations 1 smoothSolver: Solving for Uy, Initial residual = 1.54578e-05, Final residual = 4.02364e-07, No Iterations 1 GAMG: Solving for p, Initial residual = 1.02752e-06, Final residual = 7.89388e-09, No Iterations 11 GAMG: Solving for p, Initial residual = 9.77441e-08, Final residual = 7.67884e-09, No Iterations 3 GAMG: Solving for p, Initial residual = 1.00376e-08, Final residual = 7.34264e-09, No Iterations 1 time step continuity errors : sum local = 3.54801e-13, global = 5.69155e-14, cumulative = 4.14968e-11 GAMG: Solving for p, Initial residual = 3.54961e-07, Final residual = 9.34432e-09, No Iterations 10 GAMG: Solving for p, Initial residual = 3.84152e-08, Final residual = 7.93525e-09, No Iterations 2 GAMG: Solving for p, Initial residual = 8.83124e-09, Final residual = 8.83124e-09, No Iterations 0 time step continuity errors : sum local = 4.26736e-13, global = 6.29745e-14, cumulative = 4.15598e-11 smoothSolver: Solving for epsilon, Initial residual = 1.69999e-06, Final residual = 4.73952e-08, No Iterations 1 smoothSolver: Solving for k, Initial residual = 3.70653e-06, Final residual = 1.07761e-07, No Iterations 1 ExecutionTime = 557.88 s ClockTime = 562 s End Code:
Selecting incompressible transport model Newtonian Selecting turbulence model type RAS Selecting RAS turbulence model kEpsilon kEpsilonCoeffs { Cmu 0.09; C1 1.44; C2 1.92; C3 -0.33; sigmak 1; sigmaEps 1.3; } No MRF models present yPlus yPlus write: writing field yPlus patch bottom y+ : min = 11.2123, max = 22.3197, average = 15.1729 End U1a.png U5a.png V1a.png V5a.png Please help me in making changes in my case to obtain a better match with experiments. Last edited by vachan; April 8, 2018 at 06:43. |
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April 10, 2018, 06:00 |
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#2 |
New Member
Vachan Potluri
Join Date: Jul 2017
Posts: 29
Rep Power: 9 |
Figured out the reason. I was mapping the inlet conditions incorrectly. My bad!
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Tags |
kepsilon, openfoam4.1, pimplefoam, turbulence |
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