solve dimensionless equations in fluent

ashkan0065 · November 23, 2020, 23:36

Hello,
I am trying to scale down a large geometry by solving governing equations in dimensionless form. is it Necessary to write a UDF or I can do it without UDF?
thanks

LoGaL · November 24, 2020, 08:55

You should simply adimensionalize your dimensional results rather than solving dimensionless equations. E.G. create a dimensionless velocity as a custom field function V*= V/Vref and then plot that one

Or you simply scale the mesh down. I don't see the point in solving the dimensionless equations

LuckyTran · November 24, 2020, 15:35

Yeah. Fluent solves dimensioned equations. You have to non-dimensionalize it yourself using some kind of workaround.

Probably the easiest way is to scale down your geometry and boundary conditions and everything so you have the same dimensionless parameters. Refer to the Buckingham pi theorem if you are unsure how to do this.

November 23, 2020, 23:36	solve dimensionless equations in fluent	#1
ashkan0065 New Member ashkan Join Date: Oct 2020 Posts: 17 Rep Power: 5	Hello, I am trying to scale down a large geometry by solving governing equations in dimensionless form. is it Necessary to write a UDF or I can do it without UDF? thanks

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November 24, 2020, 08:55		#2
LoGaL Senior Member Lorenzo Galieti Join Date: Mar 2018 Posts: 373 Rep Power: 12	You should simply adimensionalize your dimensional results rather than solving dimensionless equations. E.G. create a dimensionless velocity as a custom field function V*= V/Vref and then plot that one Or you simply scale the mesh down. I don't see the point in solving the dimensionless equations

November 24, 2020, 15:35		#3
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,672 Rep Power: 65	Yeah. Fluent solves dimensioned equations. You have to non-dimensionalize it yourself using some kind of workaround. Probably the easiest way is to scale down your geometry and boundary conditions and everything so you have the same dimensionless parameters. Refer to the Buckingham pi theorem if you are unsure how to do this.