Setting Initial Conditions

Akim679 · September 11, 2012, 17:21

Hi,

I have a rectangular 2D channel flow and would like to set an initial condition of V=0 m/s at t=0 second and at t>0 V=2 m/s. Is there a way to do this in FLUENT version 12 without UDF?

Thanks for your help,
Akim

ghost82 · September 12, 2012, 02:27

Hi, yes, you can use profiles, but you can't have a step change..I know this is possibile with udf..
See also this post:
http://www.cfd-online.com/Forums/flu...time-step.html

Daniele

zgzhai · September 12, 2012, 05:57

you could use UDF to do it. CURRENT_TIME macro could get the time.

ghost82 · September 12, 2012, 06:05

Quote:

Originally Posted by Akim679

Hi,

I have a rectangular 2D channel flow and would like to set an initial condition of V=0 m/s at t=0 second and at t>0 V=2 m/s. Is there a way to do this in FLUENT version 12 without UDF?

Thanks for your help,
Akim

Also if you want a step change there's no need to change velocity;
start your simulation with v=2 m/s; but if you want a linear change in velocity from t=0 till t=? s you can use profile or udf as suggested.

Marion · September 12, 2012, 08:31

Can's you just initialize at 0 m/s, run the model steady state, and then switch to transient mode?

Marion.

NormalVector · September 12, 2012, 12:49

You could also do this with a Profile. Start your data with t=0, V=0 and then increment it however you'd like. Fluent will linearly interpolate between the data that you give it so if you want a step jump then it may not work.

Bdew8556 · October 30, 2022, 23:22

anyone know how to set the initial conditions in fluent? ie use a previous data file, like you can do in CFX?

September 11, 2012, 17:21	Setting Initial Conditions	#1
Akim679 New Member Akim Faisal Join Date: Jan 2012 Posts: 18 Rep Power: 14	Hi, I have a rectangular 2D channel flow and would like to set an initial condition of V=0 m/s at t=0 second and at t>0 V=2 m/s. Is there a way to do this in FLUENT version 12 without UDF? Thanks for your help, Akim

October 30, 2022, 23:22	old post i know...	#7
Bdew8556 Senior Member Brett Join Date: May 2013 Posts: 212 Rep Power: 13	anyone know how to set the initial conditions in fluent? ie use a previous data file, like you can do in CFX?

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September 12, 2012, 02:27		#2
ghost82 Senior Member Rick Join Date: Oct 2010 Posts: 1,016 Rep Power: 26	Hi, yes, you can use profiles, but you can't have a step change..I know this is possibile with udf.. See also this post: http://www.cfd-online.com/Forums/flu...time-step.html Daniele

September 12, 2012, 05:57		#3
zgzhai New Member Zhi-Gang Zhai Join Date: Sep 2012 Location: karlsruhe, Germany Posts: 7 Rep Power: 13	you could use UDF to do it. CURRENT_TIME macro could get the time.

September 12, 2012, 08:31		#5
Marion Senior Member Marion Join Date: Jul 2012 Location: France Posts: 122 Rep Power: 14	Can's you just initialize at 0 m/s, run the model steady state, and then switch to transient mode? Marion.

September 12, 2012, 12:49		#6
NormalVector Member NormalVector Join Date: Oct 2010 Posts: 71 Rep Power: 15	You could also do this with a Profile. Start your data with t=0, V=0 and then increment it however you'd like. Fluent will linearly interpolate between the data that you give it so if you want a step jump then it may not work.