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Negative Initial temperature error in openfoam

I am getting Negative initial temperature error while simulating a flow through a pipe using wedge geometry. How to avoid this error?


OpenFOAM 16-09-21, 12:42 p.m. chaitu208
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Hi,

Could you give more details regarding the initial & boundary conditions for temperature?

Regards,
Ashley
16-09-21, 12:56 p.m. ashleymelvin

Inlet temperature is 283K and constant wall temperature of 363 K.using buoyantSimpleFoam solver. Working fluid is water.


16-09-21, 1:01 p.m. chaitu208

Thanks for the details. Could you share your case files via a cloud drive and post that link here?

Regards,
Ashley


16-09-21, 1:04 p.m. ashleymelvin

The drive link is attached here.

 

https://drive.google.com/drive/folders/1Uia-sXTbzTVMmpws_959a6kI0P6u4WxW?usp=sharing


16-09-21, 2:20 p.m. chaitu208

Changing the relaxationFactor for the h equation to 0.3 in the fvSolution file seems to get the simulation to run. Please check if the simulation results are what you would expect them to be after the above change.

Regards,
Ashley 


16-09-21, 3:34 p.m. ashleymelvin

Thank you for your help. The simulation is running successfully.

I am new to cfd and openfoam. Can you explain or provide resources about the significance of residuals?

For another simulation, the residuals are converging beyond 10^-6, but after that residuals are osicallting at period intervals. So, can I consider that as a good result?


16-09-21, 3:47 p.m. chaitu208

The link below should help you understand residuals better. 

https://cfd.direct/openfoam/user-guide/v8-fvsolution/

Oscillating residuals usually signify psuedo steady-state. In some cases, this would also mean that the simulation would never converge to a steady-state such as in case of flow over cylinders at high Reynolds number causing the formation of Von Karman vortex streets. A transient analysis would better suit such problems.

Regards,
Ashley


16-09-21, 3:57 p.m. ashleymelvin

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21-03-22, 8:16 p.m. geebranz


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Hi Ashley & super mario bros: Inlet temperature is 283K and constant wall temperature of 363 K.using buoyantSimpleFoam solver.

Working fluid is water.

25-04-22, 5:05 p.m. adventpilchard


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