aneurysm case with different stl-geometries (flow through channel)

Palabos General
#1

Hello,

I tried to run the aneurysm case with different geometries. Everything works well with the aneurysm.stl, but for other geometries (for example a pipe/channel) the simulation ends after one iteration. There are 2 openings/holes in the geometry for in- and outlet and I already disabled the convergence criteria.

I don’t know why the simulation stops and I don’t see the difference between the stl-files and why my own ones don’t work.
Maybe some of you already have experience with this case and have any hint for me.

I am thankful for any help.
Best regards
Andi

Output example:


Number of fluid cells: 98304
T= 0; Average energy: 0
Offending vertex: 69.3092,3.89082,3.29445
Offending vertex: 69.3092,3.89082,34.0251
Average energy: 2129.65
Total energy: 0.102756
Pressure drop: 1.90256
Average velocity through inlet section: 0.0335725
Number of iterations: 1
Elapsed time: 0.411078
Total elapsed time: 2.45238
Description: Tot. energy, pressure-drop, tot. enstrophy,  vel1, pres1,  vel2, pres2,  vel3, pres3,  vel4, pres4,  vel5, pres5,  vel6, pres6
All data: 0.102756, 1.90256, Pos (0.022046,0.015072,0.044152); Velocity (0,0,0); Pressure -0.000140016
Pos (0.027132,0.049947,0.095012); Velocity (0,0,0); Pressure -0.000140016
Pos (0.034398,0.056487,0.057957); Velocity (0,0,0); Pressure -0.000140016
Pos (0.031492,0.025971,0.084113); Velocity (0,0,0); Pressure -0.000140016
Pos (0.025679,0.025971,0.091379); Velocity (0,0,0); Pressure -0.000140016
Pos (0.018413,0.011439,0.076848); Velocity (0,0,0); Pressure -0.000140016
0, -0.000140016, 0, -0.000140016, 0, -0.000140016, 0, -0.000140016, 0, -0.000140016, 0, -0.000140016
#2

Dear Andi,

Can you please provide a little more information:

– How did you disable the convergence criteria?
– What are the values of simTime and of your time step?

Best Regards,
Dimitris

#3

Dear Dimitris,

thank you for your fast response.
I removed convergence just fot testing case, but that wasn’t the reason of stopping. SimTime is at 100.

Time step was a good hint. I completely overlooked that it was way too big.
Reducing dt by lowering nuLB and increasing resolution helps running the simulation, but my solutions aren’t good. I had some simulations running that diverged and there was a kind of bad velocity profile visible. At the moment in all my simulations there is no velocity.


Running new simulation at level 0
uLB=0.00837001
nuLB=0.0062
tau=0.5186
dx=0.025
dt=0.0104625
Inner radius of inlet 0 : 11.9991 lattice nodes
Size of the multi-block:     206-by-30-by-30
Number of atomic-blocks:     10
Smallest atomic-block:       20-by-30-by-30
Largest atomic-block:        21-by-30-by-30
Number of allocated cells:   0.1854 million
Fraction of allocated cells: 100 percent

Number of fluid cells: 86963
T= 0; Average energy: 0
T= 2.0925; Average energy: 0.000100739
...
T= 89.9776; Average energy: 0.000255239
T= 92.0701; Average energy: 0.000232454
Average energy: 0.000226943
Total energy: 1.09501e-11
Pressure drop: -0.828351
Average velocity through inlet section: 1.83983e-05
Number of iterations: 8881
Elapsed time: 1121.66
Total elapsed time: 1123.89
Description: Tot. energy, pressure-drop, tot. enstrophy,  vel1, pres1,  vel2, pres2,  vel3, pres3,  vel4, pres4,  vel5, pres5,  vel6, pres6
All data: 1.09501e-11, -0.828351, Pos (0.022046,0.015072,0.044152); Velocity (0,0,0); Pressure -2055.47
Pos (0.027132,0.049947,0.095012); Velocity (0,0,0); Pressure -2055.47
Pos (0.034398,0.056487,0.057957); Velocity (0,0,0); Pressure -2055.47
Pos (0.031492,0.025971,0.084113); Velocity (0,0,0); Pressure -2055.47
Pos (0.025679,0.025971,0.091379); Velocity (0,0,0); Pressure -2055.47
Pos (0.018413,0.011439,0.076848); Velocity (0,0,0); Pressure -2055.47
0, -2055.47, 0, -2055.47, 0, -2055.47, 0, -2055.47, 0, -2055.47, 0, -2055.47

Thanks for your help!
Andi

#4

Seems that my simulations are okay now. Needed to test a bit with the parameters.

Best regards,
Andi

#5

Hi Andi-HH,

The post is already 2 years ago but still I have a same result as you are, my simulation end at one iteration. I found that you have the solution about that, may you advise me or explain how to do it.

The aneurysm.stl make it run properly.

Thanks for your helps,

Best Regards,
Hafizah