Hi all,

Happy New Year to Fluent-Users!!!

What is the meaning of the following Message:- "Turbulent Viscosity limited to viscosity ratio of 1.0e+5."

What is the implication? What action is to be taken in this case?

Waiting for reply.

With regards,

Lopez

1.0e+5 is set on solve/limit panel(you can change the limit values), and when the values of some cells exceed the limit value in the iteration, Fluent prints the message and replaces the exceeded values with the limit value.

Jinbok

In that case usually u need to under reluxed the control criterion, decrease the URF and keep going.

Alamgir

Dear Alamgir,

Thanx for reply. What is the implication of this? what does it physically mean? How much the URF to be decreased, Please give some guidelines for this.

Lopez

Ref: NUMERICAL HEAT TRANSFER AND FLUID FLOW-By S V Patankar. In this book u will have clear idea about ur 1st 2 questions. If u under relax that means u r taking that much quantiy from the past iteration. There is no hard and fast rule how much u need to decrease but every time decrease it by 1/2 and keep going upto 0.01. Remind if URF less u need more iterations to have converged results.

Alamgir

[bitak]

Hi.
I work on project about subsonic ejector like you.
My solve is :air - couple - axisymetric - k-e rng - pressure inlet and outlet ideal gas - my presure inlet are 150 ,250 ,350 ,450 Kpa and out let is atmosphere.
unfortunately my solve is divergence!!!!!!!!!
really I need to your help.
I change k-e to k-omega and pressure inlet to mass flow but devegence again.I know i have a shoke and so reverse flow in fluent.

[Mortie]

Originally Posted by bitak

Hi.
I work on project about subsonic ejector like you.
My solve is :air - couple - axisymetric - k-e rng - pressure inlet and outlet ideal gas - my presure inlet are 150 ,250 ,350 ,450 Kpa and out let is atmosphere.
unfortunately my solve is divergence!!!!!!!!!
really I need to your help.
I change k-e to k-omega and pressure inlet to mass flow but devegence again.I know i have a shoke and so reverse flow in fluent.

use density based k-epsilon , lower your URF and Currant number in the case of divergence, and check your mesh quality