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pisoFoam tutorial case (RAS cavity) solution breaks down after 2.5s

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Old   May 10, 2023, 08:02
Default pisoFoam tutorial case (RAS cavity) solution breaks down after 2.5s
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Jack
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I'm just starting out with OpenFOAM, hoping to use it to run some CHT cases once I familiarise myself with the basics. To that end, I've begun working through the first tutorial cases for incompressible flow (https://www.openfoam.com/documentati...en-cavity-flow). I managed to get some sensible output using the isoFoam solver, but something seems to be going wrong when I try the pisoFoam RAS cavity case.

I copied the case directory ($FOAM_TUTORIALS/incompressible/pisoFoam/RAS/cavity) to a different location to work from, and without modifying any of the settings ran blockMesh and then pisoFoam. I noticed two things that didn't seem right:
  1. Despite having deltaT=0.005, writeControl=timeStep and writeInterval=100, the solver was writing results every 0.125s of simulated time (instead of 0.5s as expected). Even when changing these settings to writeControl=runTime and writeInterval=0.5 nothing changes.
  2. The solution seems to behave normally until 2.5s of simulated time, after which point the velocity becomes completely uniform at -1m/s in the x direction across the entire domain. Similarly, the pressure becomes uniformly 0 at this point.

I'm not sure why these things are happening, especially as I initially ran the case without any modification. I noticed that the tutorial guide states that the initial turbulent dissipation rate should be eps=0.00189 rather than the default eps=0.00754, so I tried changing that, but without any luck. Does anyone have any suggestions for what I should try next?

I've attached the case folder as a .zip, and some images showing the velocity field in the solution at t=0, t=2 and t=2.625 below.

Thanks!
Attached Images
File Type: png t0.png (130.9 KB, 5 views)
File Type: png t2.png (167.3 KB, 7 views)
File Type: png t2625.png (36.2 KB, 7 views)
Attached Files
File Type: zip cavityPiso.zip (55.5 KB, 2 views)
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