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-   -   Multiphase flow convergence problems (http://www.cfd-online.com/Forums/cfx/24264-multiphase-flow-convergence-problems.html)

Nick July 12, 2007 16:01

Multiphase flow convergence problems
 
Hi,

I'm trying to model a a shear flow into a cylindrical chamber. At one end, there are two inlets, one of which is a liquid, the other is a variable composition gas, with an outlet at the other end of the cylinder.

The gas enters at high temperature and velocity, and the liquid at low temperature and velocity. The outlet has been set to an opening condition with static pressure.

I've tried just about everything to get the simulation to converge, varied the timestep, tried upwind and high resolution advection, and I've reduced the complexity of the model from a complete simulation with heat and mass transfer down to a simplified fluid dependant isothermal model.

Even with an increased resolution of the mesh (structured) the residuals just hang and oscillate about constant values. Its possible the flow is oscillatory in nature, but a qualitative inspection of the flow in cfx-post shows a definate non-physical anomoly.

Any ideas?

Glenn Horrocks July 12, 2007 21:18

Re: Multiphase flow convergence problems
 
Hi,

This topic has been discussed many times. Read the documentation about obtaining convergence. It sounds like your simulation has a minor transient component which is preventing full convergence.

Glenn Horrocks


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