Residuals - Multiphase

cfd^2 · February 12, 2014, 18:35

Hi,

I am simulating two phase gas-liquid flow with vof implicit (timestep=0.01s) using compressive scheme for volume fraction. The geometry is tree-shaped, the gas enter in one inlet and the liquid in another inlet. I am getting the strange convergence pattern of the image attached. Is it decent or something is really wrong?

cfd^2 · February 13, 2014, 07:00

NOTE: later it diverges in y-momenum.

ghost82 · February 13, 2014, 09:01

Hi!
something is wrong

you have not a converged solution; I would check the mesh/time step.

Daniele

cfd^2 · February 13, 2014, 14:54

It seems that I need a mesh very refined and a very small timestep to avoid divergence using implicit vof. I was running explicit vof with coarser mesh (but even lower timestep) using geo-reconstruct. So, the explicit vof seems to be better for this case, despite the high cost.

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February 13, 2014, 07:00		#2
cfd^2 Member cfd^2 Join Date: Mar 2013 Posts: 31 Rep Power: 13	NOTE: later it diverges in y-momenum.

February 13, 2014, 09:01		#3
ghost82 Senior Member Rick Join Date: Oct 2010 Posts: 1,016 Rep Power: 26	Hi! something is wrong you have not a converged solution; I would check the mesh/time step. Daniele

February 13, 2014, 14:54		#4
cfd^2 Member cfd^2 Join Date: Mar 2013 Posts: 31 Rep Power: 13	It seems that I need a mesh very refined and a very small timestep to avoid divergence using implicit vof. I was running explicit vof with coarser mesh (but even lower timestep) using geo-reconstruct. So, the explicit vof seems to be better for this case, despite the high cost.