Results are time step dependent

ojha.mayank485 · May 9, 2011, 22:39

Hello all,

I am trying to simulate a moving mesh problem where the motion is governed by fluid flow. i.e force_y()@Region:CYLINDER

I created the mesh in ICEM and did a grid and time convergence study for a stationary cylinder at Re=100. The residuals have an rms of 1e-05. The results obtained were accurate for a stationary cylinder but when I used the same grid for mesh motion, the results (displacements) were time step dependent. getting close to correct results for tstep=0.01 but very low values for tstep=0.001

1.) In my case should the grid convergence be done for moving mesh or stationary mesh ???

Thank you very much.

Mayank

ghorrocks · May 10, 2011, 19:00

It may well be that your moving mesh model requires a different time step size. Looks like you need to repeat the convergence study with the moving mesh model.

May 9, 2011, 22:39	Results are time step dependent	#1
ojha.mayank485 New Member Mayank Ojha Join Date: May 2011 Posts: 22 Rep Power: 14	Hello all, I am trying to simulate a moving mesh problem where the motion is governed by fluid flow. i.e force_y()@Region:CYLINDER I created the mesh in ICEM and did a grid and time convergence study for a stationary cylinder at Re=100. The residuals have an rms of 1e-05. The results obtained were accurate for a stationary cylinder but when I used the same grid for mesh motion, the results (displacements) were time step dependent. getting close to correct results for tstep=0.01 but very low values for tstep=0.001 1.) In my case should the grid convergence be done for moving mesh or stationary mesh ??? Thank you very much. Mayank

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May 10, 2011, 19:00		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,365 Rep Power: 139	It may well be that your moving mesh model requires a different time step size. Looks like you need to repeat the convergence study with the moving mesh model.