CFD Online Discussion Forums

CFD Online Discussion Forums (https://www.cfd-online.com/Forums/)
-   FLUENT (https://www.cfd-online.com/Forums/fluent/)
-   -   Oscillating residuals (https://www.cfd-online.com/Forums/fluent/225943-oscillating-residuals.html)

rizwan4081 April 12, 2020 16:22

Oscillating residuals
 
2 Attachment(s)
I am trying to perform a ventilation analysis of a tunnel with a source of fire inside it. I used the k epsilon and k omega SST for turbulence. Can please someone tell me the reason for this issue?Attachment 76420

Attachment 76421

vinerm April 13, 2020 11:32

Residuals
 
The residuals are not oscillating. You are running a transient case and the residuals are supposed to drop from rather high values to low values within each time-step. That's what you are observing.

rizwan4081 April 14, 2020 08:43

Understood. For a transient simulation I get peaks and troughs as it reaches convergence. But sometimes the trend of the oscillations are increasing in amplitude. And how can one judge the solution and say that the solution is converged?

vinerm April 14, 2020 09:16

Monitors
 
Set up a few monitor points, such as, pressure, velocity, temperature, etc., at some boundaries. These should either achieve a constant value or a periodic oscillation in the value.


All times are GMT -4. The time now is 10:04.