# Setting Initial Conditions

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 September 11, 2012, 17:21 Setting Initial Conditions #1 New Member   Akim Faisal Join Date: Jan 2012 Posts: 18 Rep Power: 6 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

 September 12, 2012, 02:27 #2 Senior Member     Daniele Join Date: Oct 2010 Location: Italy Posts: 992 Rep Power: 16 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: transient profile-time step Daniele

 September 12, 2012, 05:57 #3 New Member   Zhi-Gang Zhai Join Date: Sep 2012 Location: karlsruhe, Germany Posts: 7 Rep Power: 5 you could use UDF to do it. CURRENT_TIME macro could get the time.

September 12, 2012, 06:05
#4
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Daniele
Join Date: Oct 2010
Location: Italy
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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.

 September 12, 2012, 08:31 #5 Senior Member   Marion Join Date: Jul 2012 Location: France Posts: 122 Rep Power: 7 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 Member     NormalVector Join Date: Oct 2010 Posts: 72 Rep Power: 7 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.

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