[vachan]

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:

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

I also ran yPlus and checked that it's max value is below 30.

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

I am attaching the figures of U and V at two locations: x=1a and x=5a. (x=0 is the hill top location, 2a is the hill width).

U1a.png

U5a.png

V1a.png

V5a.png

Please help me in making changes in my case to obtain a better match with experiments.

[vachan]

Figured out the reason. I was mapping the inlet conditions incorrectly. My bad!