Hi, Developers. I simulated one particle settling in water within a tank using mfix-24.1.1, when the boundaries are all no-slip walls, the DT≈2.03E-6; setting the top boudary to pressure outflow and setting the bottom boundary to mass inflow with a velocity of 1.0m/s, the DT≈1.05E-3. Why are the time steps so different in these two cases? I plan to further simulate much more particles settling in a water tank, and it should take a long time if the time step is as small as the previous case, so I really want to figure out this problem, please help to give some guidance.
deposit.mfx (9.5 KB)
typically you should have a PO somewhere in your domain when a fluid is involved; without the solver is struggling to converge basically. Why would you not have one, especially when you simulate a water tank? Note that with water particularly, setting norm_g=1.0 in residuals on the GUI’s Numerics panel has helped in some of my work.
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Thanks Eric! It is very useful for me!