Author Topic: Turbulent viscosity limited to viscosity ratio of .... in Fluent  (Read 4015 times)

Offline infocfd

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Turbulent viscosity limited to viscosity ratio of .... in Fluent
« on: February 04, 2012, 04:36:32 PM »
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Hi,

How to resolve the warning message saying that the turbulent viscosity limited to viscosity ratio of 1e5 in 34 cells?

Help.

Offline william

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Re: Turbulent viscosity limited to viscosity ratio of .... in Fluent
« Reply #1 on: February 04, 2012, 04:37:49 PM »
The message you are seeing is more a warning than an error. It stipulates that the ratio of turbulent viscosity over the laminar viscosity is large than 1e5.

While this is not an error per-say, it is usually unphysical to have such a high ratio (note that this ratio limit is defined in Solve-> Controls -> Limits).

This ratio becomes very high in region of high turbulence, where the grid is (in most cases) too coarse.

In many case, this message occurs at the beginning of a simulation and will disappear as the simulation converges.

If it doesn't then the first step would be to refine the grid in the regions where this limit is reached (this ratio can be plotted using Display -> Contours).

You can either re-create (and refine) the grid in its entirety or you can adapt the grid "on the fly" using a grid adaptation based on the value of this ratio.
« Last Edit: April 25, 2012, 11:51:42 AM by william »