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-   -   how to define transient flow in fluent? (http://www.cfd-online.com/Forums/fluent/31084-how-define-transient-flow-fluent.html)

cynthia March 10, 2003 23:28

how to define transient flow in fluent?
 
Want to analysis the press fluctuation caused by the quick change of the inlet velocity? Thanks

Volker Pawlik March 11, 2003 06:12

Re: how to define transient flow in fluent?
 
You need to create an UDF ans of course switch the solver to unsteady. See the UDF-Tutorials or the examples in the UDF-Handbook. They provide a UDF with a sinus-based time dependent inlet-function:

************************************************** ********************/

/* unsteady.c */

/* UDF for specifying a transient velocity profile boundary condition */ /************************************************** ********************/

#include "udf.h"

DEFINE_PROFILE(unsteady_velocity, thread, position) { face_t f;

begin_f_loop(f, thread)

{

real t = RP_Get_Real("flow-time");

F_PROFILE(f, thread, position) = 20. + 5.0*sin(10.*t);

} end_f_loop(f, thread) }

Volker

Turtle March 11, 2003 14:36

Re: how to define transient flow in fluent?
 
Right! As Volker mentioned, you can use as the inlet transient condition with this example file. This file was set for the inlet velocity to change as time like sinusoidal wave. For more detailed, refer the manual and handbook or contact the Fluent inc.

Turtle March 11, 2003 14:37

Re: how to define transient flow in fluent?
 

cynthia March 12, 2003 09:53

Re: how to define transient flow in fluent?
 
thanks!:)


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