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Lior February 11, 2004 12:32

Pulsatile Flow Boundary Conditions
Hi everyone! I am trying to simulate 2-D pulsatile flow of blood through arterial stenosis. I was wondering how should i define the boundary conditions for the inlet pulsatile flow waveform? The blood flow inlet has a specific waveform (according to the heart systole and diastole pattern) which repeats itself every ~1 second. I guess i should use a UDF, but how do i define it as a boundary condition in the inlet? Thanks.

solomon February 12, 2004 04:38

Re: Pulsatile Flow Boundary Conditions

The following is the udf for pulsatile velocity boundary condition which you can use it as inlet. It is one of the examples in fluent documentation manual under the section udf.

I do hope you have the appropriate equation to desiginate arterial pulsatile velociy profile. You need to substitute the sine function here with it.

You will need to interpret or compile this udf; instructions on how to do so are in influent manual. Once compiled/interpreted the function appears in your list of inlet boundary condition. From there you make your selection.

#include "udf.h"

DEFINE_PROFILE(unsteady_velocity, thread, position) { face_t f; real t = CURRENT_TIME;

begin_f_loop(f, thread)


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

} end_f_loop(f, thread) }


Lior February 12, 2004 06:49

Re: Pulsatile Flow Boundary Conditions
Hi Solomon, Thank you for your clear and fast response. I will try and follow your instructions, in order to fit the inlet boundary condition. Best regards, Lior.

adi.ptb April 20, 2014 07:26

hi,I want to simulate a pulsating unsteady turbulent flow in a pipe,due to symmetry i generated half of its geometry,i used a udf to define the inlet velocity and temperature,i get the solution converged but when i plot the area weighted average vs flow time at the centerline i keep getting zero values for axial velocity,can anyone help me please

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