CFD Online Logo CFD Online URL
Home > Forums > FLUENT

convergence of mixture model

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Display Modes
Old   October 4, 2004, 09:27
Default convergence of mixture model
Posts: n/a
My problem is about two-phase flow:liquid and gas.There is a big volume. The liquid inlet is in the upper of the voluem. Two gas inlets are at the bottom. Two outlets are also at the bottom. The structure is symmetry to x and y axle. I select mixture as the multiphase model. The firs step,I didn't select slip velocity and volum fraction of gas. The convergence criterio are 1.0e-05. When converged,I open repor panel. The mass flow of inlet is not equal to that of outlet. Can I consider it has convegerd? And why the mass flow of inlet is not equal to that of outlet? The boundary conditions: inlet:velocity inlet; outletutflow Thanks a lot!
  Reply With Quote

Old   October 5, 2004, 13:47
Default Re: convergence of mixture model
Posts: n/a

i am also experiencing same problem with my model as the residuals have gone below 10-7 or so but there is mass imbalance later when i asked somebody here at post following was said by him:

It's not unusual there is some imbalance. Usually it's possible to solve this problem by reducing the value of residual reduction required for convergence. Also try to use a higer order dicretization scheme for convective terms in the solver settings (Solve -> Control -> Solution)...... (ap)

hope its helps

  Reply With Quote

Old   October 5, 2004, 21:28
Default Re: convergence of mixture model
Posts: n/a
thank you very much! I have reduced the relaxion factors and use the second order dicretization scheme. Mass flow is still imbalence. Mr. Ally, have you solved this problem? And when I change the outlet boundary condition from outflow to pressure outlet, the velocitis of primary phase and secondary phase are different. I don't know which one is correct. Perhaps they are all false for I haven't acquired the converged solutions.
  Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Water subcooled boiling Attesz CFX 7 January 5, 2013 04:32
A question about UDF utility in mixture and multiphase model aleisia Fluent UDF and Scheme Programming 0 June 7, 2011 16:32
convergence problem of the SST and RNG k-e model for mixing tank ziyan7 FLUENT 0 March 8, 2011 07:13
mixture model for rotating bowl garima chaudhary FLUENT 1 January 30, 2008 19:24
Convergence problems with SSG turbulence model Ram CFX 1 June 19, 2006 10:08

All times are GMT -4. The time now is 04:05.