Incorrect results for 2D flow between flat plates
 

Hello,


I am new to OpenFOAM. I just ran a simulation for laminar flow between two flat plates (0.1m apart) using the icoFoam solver. The inlet velocity was 0.01m/s and nu was 3.33e-05.Only half the problem was simulated due to symmetry. The outlet pressure was a fixed value of 0. The wall was given a no-slip condition for velocity and zeroGradient for pressure. The problem was simulated for 60 seconds. I used 20x200 and 40x400 meshes.



I have attached the results of the fine mesh. For some reason the results are inaccurate. Clearly mass is not conserved as the velocity has decreased near the walls but has not increased in the middle as expected. I am not sure why this is happening. Could I be missing some setting on OpenFOAM?


Here is the residuals info for the final time-step (there is no indication that continuity is not met, is there?):


Time = 60

Courant Number mean: 0.0178753 max: 0.0386888
smoothSolver: Solving for Ux, Initial residual = 2.23147e-09, Final residual = 2.23147e-09, No Iterations 0
smoothSolver: Solving for Uy, Initial residual = 9.08946e-09, Final residual = 9.08946e-09, No Iterations 0
DICPCG: Solving for p, Initial residual = 1.67006e-06, Final residual = 7.39157e-07, No Iterations 1
DICPCG: Solving for p, Initial residual = 7.39157e-07, Final residual = 7.39157e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.39157e-07, Final residual = 7.39157e-07, No Iterations 0
time step continuity errors : sum local = 2.7874e-11, global = -1.38466e-11, cumulative = -1.89192e-09
DICPCG: Solving for p, Initial residual = 7.445e-07, Final residual = 7.445e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.445e-07, Final residual = 7.445e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.445e-07, Final residual = 7.445e-07, No Iterations 0
time step continuity errors : sum local = 2.80755e-11, global = -1.4021e-11, cumulative = -1.90594e-09
ExecutionTime = 14.87 s ClockTime = 18 s


Thanks for the help.

I have figured out the mistake. I had mentioned the symmetry boundary as 'symmetryPlanes' rather than 'symmetryPlane' in blockMeshDict. Also, I had given zeroGradient boundary condition for 'type' concerning the symmetry plane rather than 'symmetryPlane'.