Expression for uniform flow

ABrueck · February 10, 2016, 11:08

Hello,

I'm modelling an exotic diffusor with high opening angle.

Within a parametric study I want wo find a configuration with the most uniform velocity profile at the outlet of the diffusor.

To compare different configurations, I thought about something like standard deviation and tried 'areaave(velocity.diversity)@<location>' as an expression, but I get [s^-1] as a dimension whereas I expected a dimensionless result.

In the CFX-Refernce Guide I do not finde any documentation for the velocity.<subexpressions>.

So the question is: Is there a Ansys expression to get the unifomity of the veolocity profile or do I have have to do the job with an external program?

I'm using Ansys 13

Thank you for any answer,
Kind regards,
Arjun

ghorrocks · February 10, 2016, 17:31

I don't know if this will work, but can you do something like:

rmsAve((u-areaAve(u)@location)@location

Opaque · February 10, 2016, 21:05

Keep in mind that such expression may only work in CFD-Post.

In the ANSYS CFX Solver, you must split the expression in parts such as

Create an algebraic additional boundary only variable,

MyBdyAV = u - areaAve(u)@location

MyUniformity = rmsAve(MyBdyAV)@location

Hope Glenn's suggestion works for you on either the solver, or post.

February 10, 2016, 11:08	Expression for uniform flow	#1
ABrueck New Member Arjun Brueck Join Date: Jan 2016 Posts: 1 Rep Power: 0	Hello, I'm modelling an exotic diffusor with high opening angle. Within a parametric study I want wo find a configuration with the most uniform velocity profile at the outlet of the diffusor. To compare different configurations, I thought about something like standard deviation and tried 'areaave(velocity.diversity)@<location>' as an expression, but I get [s^-1] as a dimension whereas I expected a dimensionless result. In the CFX-Refernce Guide I do not finde any documentation for the velocity.<subexpressions>. So the question is: Is there a Ansys expression to get the unifomity of the veolocity profile or do I have have to do the job with an external program? I'm using Ansys 13 Thank you for any answer, Kind regards, Arjun

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February 10, 2016, 17:31		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	I don't know if this will work, but can you do something like: rmsAve((u-areaAve(u)@location)@location

February 10, 2016, 21:05		#3
Opaque Senior Member Join Date: Jun 2009 Posts: 1,804 Rep Power: 32	Keep in mind that such expression may only work in CFD-Post. In the ANSYS CFX Solver, you must split the expression in parts such as Create an algebraic additional boundary only variable, MyBdyAV = u - areaAve(u)@location MyUniformity = rmsAve(MyBdyAV)@location Hope Glenn's suggestion works for you on either the solver, or post.