CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > ANSYS > FLUENT

Problems with residuals??

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

LinkBack Thread Tools Search this Thread Display Modes
Old   November 29, 2000, 04:48
Default Problems with residuals??
Peter Kolb
Posts: n/a
Hi CFD-users,

I'm a FLUENT 5.4.- user and I try to simulate the flow inside a stirred tank. For the motion of the stirrer I use the MRF-Model. The viscous model is the standard k-epsilon. I begin my calculations with very low rotational speed and after reaching a destined convergence, I increase the speed. When I postulate small scale residuals it's no problem for the x-velocity, y-velocity, z-velocity, k and epsilon to get a small value. At 10^-7 they all reach a kind of "steady state" where no changes could be recognized; but the continuity reach a stedy state at 10^-6. When I now increase the rotational speed step by step, all residulas will find "this steady state" at the value 10^-7 again except for the continuity. The residual for the continuity is increasing while I increase the speed. To my questions: 1)Is this normal that the residual for the continuity is increasing while I increase the speed? 2)What adjustments do I have to change to solve this problem?

Solve Control Solution:

Under-relaxation factors Pressure 0.3 Momentum 0.7 Turbulence Kinetic Energy 0.8 Turbulence Dissipation Rate 0.8 Viscosity 1.0 Density 1.0 Body Forces 1.0

Discretization Pressure PRESTO! Momentum First Order Upwind Pressure-Velocity Coupling SIMPLE Turbulence Kinetic Energy First Order Upwind Turbulence Dissipation Rate First Order Upwind

Thanks Peter

  Reply With Quote


Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
[ICEM] Problems with coedge curves and surfaces tommymoose ANSYS Meshing & Geometry 6 December 1, 2020 12:12
Problems with residuals oscillations spacecraft STAR-CCM+ 2 September 13, 2010 09:57
problems with residuals in fluent. Tan FLUENT 3 February 10, 2009 11:05
Problems with residuals Martin CFX 2 January 2, 2007 23:10
Convergence - scaled vs unscaled residuals HS FLUENT 1 November 7, 2005 06:45

All times are GMT -4. The time now is 15:20.