Slosh Analysis

Aashi171185 · June 14, 2019, 01:57

Sir i am doing sloshing analysis in a closed container i selected the time step by doing couple of analysis from 0.1 sec to 0.01sec loading in my case is disx which is sinusoidal in nature but my solution shows divergence behavior i.e for 0.025 sec time step it shows divergence from 10 to 20 time steps but when i reduced the time step it moves forward to 20 to 30 time step and as i went towards lowering time step to halve of the previous value it also moves half time forward
i have also tried adaptive time stepping but my transient solution shows the same behavior sir please guide me to get rid of this problem and also guide me to calculate the time step from courant number in sloshing case

ghorrocks · June 14, 2019, 07:55

The recommended approach is to use adaptive time stepping, homing in on 3-5 coeff loops per iteration. Make sure the initial and minimum time step size are small enough that it converges fine.

If you have done this simulation please post the output file from it, and an image of the geometry.

June 14, 2019, 01:57	Slosh Analysis	#1
Aashi171185 Member Aashi Join Date: Dec 2018 Posts: 43 Rep Power: 7	Sir i am doing sloshing analysis in a closed container i selected the time step by doing couple of analysis from 0.1 sec to 0.01sec loading in my case is disx which is sinusoidal in nature but my solution shows divergence behavior i.e for 0.025 sec time step it shows divergence from 10 to 20 time steps but when i reduced the time step it moves forward to 20 to 30 time step and as i went towards lowering time step to halve of the previous value it also moves half time forward i have also tried adaptive time stepping but my transient solution shows the same behavior sir please guide me to get rid of this problem and also guide me to calculate the time step from courant number in sloshing case

June 14, 2019, 07:55		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	The recommended approach is to use adaptive time stepping, homing in on 3-5 coeff loops per iteration. Make sure the initial and minimum time step size are small enough that it converges fine. If you have done this simulation please post the output file from it, and an image of the geometry. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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