Macros for access turbulence intensity

asal · October 10, 2015, 08:00

Hello all!

I want to calculate some a value in a UDF and I need to have "turbulence intensity". Is there anyone here know how can I return this value?
I mean a macro such as " C_U(c,t)" which return turbulence intensity.

moreover, is there any macro which return velocity magnitude? or the only way is to return components and then find the magnitude?

`e` · October 11, 2015, 16:36

Fluent doesn't store turbulence intensity by default. However, you can calculate this value as turbulence intensity is defined as the ratio between the root-mean-square turbulent velocity fluctuations and the mean velocity.

The velocity fluctuations can be computed as a function of the kinetic energy (for example, k-e) or via the Reynolds stresses (RSM model). The mean velocity (not stored as a separate value by default) is the magnitude of the individual components.

October 10, 2015, 08:00	Macros for access turbulence intensity	#1
asal Senior Member Astio Lamar Join Date: May 2012 Location: Pipe Posts: 186 Rep Power: 14	Hello all! I want to calculate some a value in a UDF and I need to have "turbulence intensity". Is there anyone here know how can I return this value? I mean a macro such as " C_U(c,t)" which return turbulence intensity. moreover, is there any macro which return velocity magnitude? or the only way is to return components and then find the magnitude?

October 11, 2015, 16:36		#2
`e` Senior Member Join Date: Mar 2015 Posts: 892 Rep Power: 18	Fluent doesn't store turbulence intensity by default. However, you can calculate this value as turbulence intensity is defined as the ratio between the root-mean-square turbulent velocity fluctuations and the mean velocity. The velocity fluctuations can be computed as a function of the kinetic energy (for example, k-e) or via the Reynolds stresses (RSM model). The mean velocity (not stored as a separate value by default) is the magnitude of the individual components. asal likes this.

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