Inlet/Outlet - Vortex Error

Hello guys!

Thanks for the new release, very exciting. I have modified the example with flow over cylinder a bit, and I think I found something less optimal:



Instead of a cylinder I placed a rectangle covering 3/4 of the width of the channel, and the problem I observe is marked with yellow that the particle density is getting scarily low. This might be in connection with the second problem I observe which is that suddenly back flow occurs due to rotation of fluid:


Which of course can be solved by making the channel longer, but then I get a a very high amount of particles. Has anybody found another fix for this situation?

Kind regards

ds.PNG 474.3K

Comments

  • I made it longer now, to avoid the vortex overlap issue, but the issue with particles falling down still occurs. Gravity is not enabled.



    Trying to keep testing, any suggestions would be welcome!
    ds2.PNG 260.4K
  • The error seems to have be found - a very high shifting coefficient of -20 was used in the example. By lowering it to two I see:



    So now I am trying to adjust shifting until it stays "physically" correct.
    ds3.PNG 194.8K
  • Asalih,

    You should provide your XML section of I/O so we can see exactly what you are doing.
    Yes, you need to adjust your shifting coefficient to act sufficiently well for your case.
    Also, I would recommend checking that the threshold for the shifting correction at the free surface is not active, set that equal to a negative number to be sure.
  • @taffo thanks!

    Here it is as requested. I will try setting ShiftTFS to -5 instead of 0, but should be the same. Do you have any more suggestions?

    Kind regards
  • Now I've changed to artifical viscosity, and the problem with voids have been solved, but unfortunately, it seems like the SPH method cannot handle vortices at the outlet, which means I have to use way too many particles I think. Maybe I am doing something wrong:



    Picture to show what I mean. Coloured by idp
    dss3.PNG 230.5K
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