Solver Error


#1

I am trying to run a sim ( https://www.simscale.com/workbench/?pid=8814826337149936545#tab_1-0 ) but when it reached Time=6 it crashed .What does this warning mean?


#2

Hi @kkotsarinis and thanks for reaching out to us!

The @PowerUsers_CFD and I will have a look at that and get back to you as soon as we know more!

Cheers!

Jousef


#3

Hi @kkotsarinis,

Your Specific turbulence dissipation rate [1/s] has a rather high value. Is this supposed to be correct?

Cheers.

Regards,
Barry


#4

Hi @Get_Barried
Yes , i repeated the calculations and i don’t think it is that high as a value, comparing with other cases on fase cars.


#5

Hi @kkotsarinis,

The very high value is probably the issue. Try setting it to maybe a default value and see if you still have instability.

Cheers.

Regards,
Barry


#6

@Get_Barried Ι changed the value and the simulation did not crash.Now it calculates huge numbers of forces unfortunately .What may be the problem this time? (https://www.simscale.com/projects/kkotsarinis/project18_1/ )


#7

Hi @kkotsarinis,

Do you have any literature dictating the calculation of your Omega? This reference project here has a much smaller Omega value, almost 10x smaller, which I believe is causing your high force values.

Cheers.

Regards,
Barry


#8

@Get_Barried
I am following this tutorial ( Session 1 - TUTORIAL - Ride Height Analysis )where you can see that an even higher value of omega is used. Also I use the formulas used in this page ( https://www.simscale.com/docs/content/simulation/model/turbulenceModel/kOmegaSST.html ) . Finally to double check the calculation i used also the spreadsheet given in this link (https://docs.google.com/spreadsheets/d/1LV_-y3TwOaOWnyQHgvjHVmzBEPuY_un6PFMJY45ozfU/edit#gid=1223612336) that i found in this forum (Step-by-Step Tutorial: Homework of Session 2). Thank you for your time!


#9

Hi @kkotsarinis,

Yup it does seem you did everything correctly unless I missed something. Very peculiar indeed. Let me tag my other fellow @PowerUsers_CFD who may able to help you with your problem!

I’ll keep looking around but for now they might be able to give you a quicker response!

Cheers.

Regards,
Barry


#10

@PowerUsers_CFD Did you find out what may be wrong? The Mesh Operation Event Log shows : " Mesh quality check failed. The mesh is not OK.Mesh quality report could not be created due to an invalid edge with zero or negative length in the mesh." but when I checked the meshing log and i found out this log:

Checking final mesh …
Checking faces in error :
non-orthogonality > 75 degrees : 0
faces with face pyramid volume < 1e-16 : 0
faces with concavity > 80 degrees : 0
faces with skewness > 4 (internal) or 20 (boundary) : 0
faces with interpolation weights (0…1) < 0.01 : 0
faces with volume ratio of neighbour cells < 0.0075 : 0
faces with face twist < 0.005 : 0
faces on cells with determinant < 0.005 : 0
Finished meshing without any errors
Finished meshing in = 1679.65 s.
End
Finalising parallel run


#11

Hi @kkotsarinis!

The mesh seems to be fine. Having a look as soon as I am home and will tell you if I could find anything. In the meanwhile, feel free to jump in @PowerUsers_CFD.

Best,

Jousef