CFD Online Logo CFD Online URL
Home > Forums > Main CFD Forum

Change in coefficients

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

LinkBack Thread Tools Display Modes
Old   December 4, 2001, 12:34
Default Change in coefficients
Posts: n/a
Hello, I am solving the Unsteady Convection-Diffusion eq. with variable coefficients on the form:

C1*dU/dt+ d/dx[C2*u*U]=d/dx[C3*dU/dx]

the coefficients very sensitive to the value of U, i.e. C's=fnc(U). This makes my code fail to converge. What I am using is upwind finite difference to Convection term and Central difference to Diffusion term (implicit scheme). At each time step, as an attempt to reach a converged solution, I hold the time and try to make a series of Iteration in order for solution to converge on this form:

C1=(1-UR)*C1(Previous) + UR*C1(Current)

where UR-under-relaxation parameter. But I failed with different values of UR {0.001<UR<1} Any suggestion would be appreciated.
  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
ODE solver coefficients mrangitschdowcom OpenFOAM Running, Solving & CFD 2 August 18, 2013 22:16
Change cell zone index/thread during simulation neilduffy1024 FLUENT 0 January 17, 2011 10:40
change velocity if coefficients converged WolfgangS. OpenFOAM 0 December 10, 2010 12:56
no enthalpy change across the momentum source Atit Koonsrisuk CFX 2 December 19, 2005 03:33
Multicomponent fluid Andrea CFX 2 October 11, 2004 05:12

All times are GMT -4. The time now is 08:37.