Dear all,
I am trying to ru
Dear all,
I am trying to run the icoFoam cavity case with the block size of 92*92*32 and defult sets. But I was told the error of time as follows. Could you please help me see and give advice? Thanks a lot. Errors: Time = 0.02 Mean and max Courant Numbers = 0.109749 132.97 BICCG: Solving for Ux, Initial residual = 0.769511, Final residual = 9.41873e06, No Iterations 38 BICCG: Solving for Uy, Initial residual = 0.725626, Final residual = 3.13877e06, No Iterations 36 BICCG: Solving for Uz, Initial residual = 0.8086, Final residual = 9.13794e06, No Iterations 35ICCG: Solving for p, Initial residual = 0.953251, Final residual = 9.12515e07, No Iterations 265 time step continuity errors : sum local = 3.04285e07, global = 1.32364e18, cumulative = 1.65714e18 ICCG: Solving for p, Initial residual = 0.841697, Final residual = 9.02924e07, No Iterations 242 time step continuity errors : sum local = 1.65841e06, global = 5.28474e18, cumulative = 6.94188e18 ExecutionTime = 192.11 s Time = 0.025 Mean and max Courant Numbers = 1.37811 15395.5 BICCG: Solving for Ux, Initial residual = 0.997305, Final residual = 0.0301471, No Iterations 1001 BICCG: Solving for Uy, Initial residual = 0.997675, Final residual = 15.8377, No Iterations 1001BICCG: Solving for Uz, Initial residual = 0.999334, Final residual = 0.00554499, No Iterations 1001 ICCG: Solving for p, Initial residual = 0.999822, Final residual = 9.36367e07, No Iterations 124 time step continuity errors : sum local = 0.00903109, global = 3.98103e15, cumulative = 3.97409e15 ICCG: Solving for p, Initial residual = 0.998574, Final residual = 9.58777e07, No Iterations 132 time step continuity errors : sum local = 5.25563, global = 4.08839e11, cumulative = 4.08799e11ExecutionTime = 748.68 s Time = 0.03 Mean and max Courant Numbers = 1.61369e+06 5.99557e+10 BICCG: Solving for Ux, Initial residual = 1, Final residual = 1, No Iterations 1001 BICCG: Solving for Uy, Initial residual = 1, Final residual = 1, No Iterations 1001 BICCG: Solving for Uz, Initial residual = 1, Final residual = 1, No Iterations 1001 ICCG: Solving for p, Initial residual = 1, Final residual = 51.6963, No Iterations 5001 time step continuity errors : sum local = 2.80935e+17, global = 2.2091, cumulative = 2.2091 ICCG: Solving for p, Initial residual = 1, Final residual = 56.148, No Iterations 5001 time step continuity errors : sum local = 7.65932e+26, global = 1.49149e+09, cumulative = 1.49149e+09 ExecutionTime = 1827.63 s End 
I may be wrong, but looks like
I may be wrong, but looks like your mesh is too fine. Maybe you can try to reduce time step.
Regards. 
Dear Charles Ju:
Thanks for
Dear Charles Ju:
Thanks for your advice. my using time step is 0.005 and stop on 0.03. writeInterval is 1. Please give more details. Thanks deeply. Guoxiang 
Hi.
Maybe time step = 0.001 o
Hi.
Maybe time step = 0.001 or 0.0001? Or you could increase cell sizes. Also wrong boundary conditions will cause diverging solutions. Check them too. Regards. 
Dear Charles Ju:
Thanks ag
Dear Charles Ju:
Thanks again. I will check as you said. By the way, the boundary conditions were checked which was ok by run checkMesh. I am not sure whether it is ok or not. I will tell you after test. Thanks deeply. Guoxiang 
Boundary condition are checked
Boundary condition are checked by yourself, not checkMesh.
Do some coarse mesh calculation to see what will happen. 
Dear Charles Ju:
I have ch
Dear Charles Ju:
I have change as you said, but the problem is same. Do you have another advice? Thanks deeply. Guoxiang 
Dear Xiaofeng:
Thanks a lot
Dear Xiaofeng:
Thanks a lot. Just now, I checked the boundary file. My nFaces is: 28704, but the startFace is: 798192 So I think something is wrong here since startFace is further more the nFace. Could you please give some advice? Thanks deeply, Guoxiang 
Dear All,
I still do not so
Dear All,
I still do not solve this questions yet. I have changed to small time step and checked the boundary. It likes ok. But the "time step continuity errors :" problem is still here. Could you please help me? 
Obviously something is wrong w
Obviously something is wrong with one of your files, so why don't you just copy a whole new/fresh icoFoam cavity case from inside /tutorials directory and then run blockMesh and icoFoam.
AFAIR there's also an .allrun file which works straight "outofthebox". 
Dear Martin Jørgensen:
Than
Dear Martin Jørgensen:
Thanks for your help. You mean I should use Allrun to instead of the blockMesh and icoFoam. Right? Thanks again. Guoxiang 
Hi Guoxiang,
I mean: (under
Hi Guoxiang,
I mean: (under linux), standing inside your working directory  that would probably be something like (can't exactly remember if this path is correct, however here we go): cd /home/guoxiang/OpenFOAM/OpenFOAM1.2/guoxiang1.2/run/tutorials I would then do a recursive remove on this directory that doesn't work "rm rf icoFoam/cavity"  notice that you should make sure you have a backup somewhere of the original directory which in my place would be in something like /OpenFOAM/OpenFOAM1.2/run/tutorials. If you did like in the readme file that ships with openfoam, you would also have a backup. So, standing in your working directory: "cp r /OpenFOAM/OpenFOAM1.2/run/tutorials/icoFoam/cavity (place you want your working copy like for instance .)" Then ./allrun worked for me (blockMesh and icoFoam should also work) as far as I remember and once you made sure everything is okay, you can experiment by changing mesh grading etc (in blockMeshDictfile). I assume you once already have solved this case, right? 
Dear Martin Jørgensen:
Tha
Dear Martin Jørgensen:
Thanks a lot. Just now, I have tries as you said, But the problem is still same. Could you have another advice? Thank you very much. xiang 
Yep, attach your case here in
Yep, attach your case here in a compressed file so others can download it and try for themselves.

Dear Martin Jørgensen:
I ha
Dear Martin Jørgensen:
I have a test when I reinstalled. But the question is still here. It is very strange. I use the cavity in icoFoam case. I have really no idea. I do not how to do? Thanks a lot. xiang 
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