Oscilliations in Multiphase simulation

frono · November 27, 2010, 22:29

I have been having a problem when running a transient multiphase simulation using the implicit segregated solver in Star CCM+ ver 5.04.08.

I have been running a series of simulations using the 6-DOF solver released for y rotation and z motion.

I have been using drag as stopping criteria for convergence, as well as sinkage, trim and, momentum residuals.

The solution converges, but continues to oscilliate. At times the oscilliations begin to build again and the solution starts to diverge. does anyone else have any experience with this?

chinc · April 12, 2011, 23:03

I have seen oscillation that getting wilder while the velocity profile showed convergence for a 3D simulation for external building flows. Could such a problem due to the mesh quality? i.e. high mesh transition ratio (4 times) from far field to the region of interest.

Also, it is found that the convergence for CCM+ is very slow and normally will exhibit likelihood of divergence prior to convergence. Does any users in this forum experience the similar scenario?

Appreciate all the sharing and discussions.

November 27, 2010, 22:29	Oscilliations in Multiphase simulation	#1
frono New Member Join Date: Nov 2010 Posts: 1 Rep Power: 0	I have been having a problem when running a transient multiphase simulation using the implicit segregated solver in Star CCM+ ver 5.04.08. I have been running a series of simulations using the 6-DOF solver released for y rotation and z motion. I have been using drag as stopping criteria for convergence, as well as sinkage, trim and, momentum residuals. The solution converges, but continues to oscilliate. At times the oscilliations begin to build again and the solution starts to diverge. does anyone else have any experience with this?

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April 12, 2011, 23:03		#2
chinc New Member Join Date: Aug 2009 Posts: 18 Rep Power: 17	I have seen oscillation that getting wilder while the velocity profile showed convergence for a 3D simulation for external building flows. Could such a problem due to the mesh quality? i.e. high mesh transition ratio (4 times) from far field to the region of interest. Also, it is found that the convergence for CCM+ is very slow and normally will exhibit likelihood of divergence prior to convergence. Does any users in this forum experience the similar scenario? Appreciate all the sharing and discussions.