Want to analysis the press fluctuation caused by the quick change of the inlet velocity? Thanks

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

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.

thanks!