# trying why my runs diverge - simple case I built

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October 28, 2023, 15:55
trying why my runs diverge - simple case I built
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Join Date: Oct 2023
Posts: 5
Rep Power: 2
So I have the following case that I built, the mesh lis ok (used checkMesh), and developed the the required constants. However, when I run simpleFoam or foamRun, it starts to solve up to certain point and then it starts to produce nan.
For example, see below

HTML Code:
```[CODE]SmoothSolver:  Solving for Ux, Initial residual = 0.91362581, Final residual = 9.1691167e-06, No Iterations 36
smoothSolver:  Solving for Uy, Initial residual = 0.97344182, Final residual = 7.8785232e-06, No Iterations 34
smoothSolver:  Solving for Uz, Initial residual = 0.99999992, Final residual = 8.4295095e-06, No Iterations 37
GAMG:  Solving for p, Initial residual = 1, Final residual = nan, No Iterations 1000
time step continuity errors : sum local = nan, global = nan
GAMG:  Solving for p, Initial residual = nan, Final residual = nan, No Iterations 1000
time step continuity errors : sum local = nan, global = nan, cumulative = nan
smoothSolver:  Solving for epsilon, Initial residual = nan, Final residual = nan, No Iterations 1000
smoothSolver:  Solving for k, Initial residual = nan, Final residual = nan, No Iterations 1000
ExecutionTime = 15.673765 s  ClockTime = 15 s

Courant Number mean: nan max: nan
Time = 0.0469628s

smoothSolver:  Solving for Ux, Initial residual = nan, Final residual = nan, No Iterations 1000
smoothSolver:  Solving for Uy, Initial residual = nan, Final residual = nan, No Iterations 1000
smoothSolver:  Solving for Uz, Initial residual = nan, Final residual = nan, No Iterations 1000
[/CODE]```
My files are provided below - any help would be appreciated.
Attached Files
 pitzDai2.zip (24.1 KB, 4 views)

 October 29, 2023, 14:08 #2 Senior Member   Join Date: Apr 2020 Location: UK Posts: 640 Rep Power: 13 Looks like you are trying to run as a transient simulation. Try changing over to steady state: - in fvSchemes, change ddtSchemes default from Euler to steadyState - in fvSolution, comment out the PIMPLE section and add the following: Code: ```SIMPLE { nNonOrthogonalCorrectors 0; consistent yes; residualControl { p 1e-2; U 1e-3; "(k|epsilon)" 1e-3; } } relaxationFactors { fields { p 0.3; } equations { U 0.7; k 0.7; epsilon 0.7; } }``` - in controlDict, change deltaT to 1 Now run with simpleFoam, and this should converge/behave nicely. Good luck! chemotkbilo likes this.