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-   -   problems with residuals in fluent. (http://www.cfd-online.com/Forums/fluent/50514-problems-residuals-fluent.html)

Tan February 9, 2009 08:42

problems with residuals in fluent.
 
Hi

I am having problems with my residuals in fluent. Tmy velocities and energy lines are both dropping to 1e-06 but my k , epsiolon and most important contuinity are not dropping below 1e-03??

i am modelling a simple closed cavity in a pipe. my inlet for the pipe has - a massflow = 0.305kg/s - turbulence intensity=5% - length scale=61mm (diamater of my pipe) - temp 291k

outlet;

-gauge pressure of 0 -turbulence intensity=0.01 -length scale=61mm

i have messed around with my mesh to make it finer where i have seen high velocity or turbulence values but no matter how fine i make it i cannot get the residuals to drop??

i am using a p-v coupling= coupled with standard default values

canyone help or suggest anything?

thanks in advance

Tan

mange February 9, 2009 09:30

Re: problems with residuals in fluent.
 
Are you sure that your fields are not converged? if you disregard the residuals and look at your flow field variables

If you have been doing adaptive refining. I would suggest that you re-mesh your domain in your preprocessor. There you can control your resolution and hopefully get a good quality mesh.

otherwise try p-v coupling = simple.

have fun!


tan February 9, 2009 09:46

Re: problems with residuals in fluent.
 
hi

yeah my flow walues seem to converge i.e.x,y,z velocities and my mass flow is conserved alongside my temp.

but its this contuinuituy k and epsilon value which is hovering around 1e-03 .

i ahve been refining my model manually in gambit not used any auto adaption?

tried p-v coupling =simple initially but i get error; divergence detected in AMG solver: pressure correction

help!

tan February 10, 2009 11:05

Re: problems with residuals in fluent.
 
hi

me again! sorry

i have tried using a turbulencevalues

turb ke =24 turbulence disspaption rate =4524

still no luck on k, eps and contuinuity converging?



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