[bazinga22]

Hello all,

I am working to create a UDF that represents a breathing pattern for a 3D transient simulation. The UDF is set for the massflow rate of the persons nostril.

The pattern lasts 6 seconds is pretty much just a sine-wave when t<5, but from t=5 to t=6 the person is resting and the breathing mass flow rate is 0 as seen in the screen shot attached. However I cannot figure out how to loop this to continue "infinitely" as right now the breathing waveform runs once through from 0-6 seconds and I would like it to continue/restart the same pattern 6-12 s, 12-18 s and so on....

Can anyone help me with fixing my code to do so? Thank you!

[AlexanderZ]

/*************************
transient.c
UDF for specifying a transient boudnary condition
******************************/

#include "udf.h"

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

	begin_f_loop(f, thread)
	{
	 	F_PROFILE(f, thread, position) = .000125*sin((2*M_PI*(t%5))/5);
	}
	end_f_loop(f, thread)
}

[bazinga22]

Hi thank you, this doesn't work I don't believe, because I need the 1s of rest from 5 to 6 seconds of 0 flow rate. Your reply will just loop the sine function every 5 seconds.

Any other thoughts?

[AlexanderZ]

lol

/*************************
transient.c
UDF for specifying a transient boudnary condition
******************************/

#include "udf.h"

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

	begin_f_loop(f, thread)
	{
		if (t%6 == 0)
			F_PROFILE(f, thread, position) = 0.0;
		else
			F_PROFILE(f, thread, position) = .000125*sin((2*M_PI*(t%6))/5);
	}
	end_f_loop(f, thread)
}

[tiztaz]

Originally Posted by AlexanderZ

lol

/*************************
transient.c
UDF for specifying a transient boudnary condition
******************************/

#include "udf.h"

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

	begin_f_loop(f, thread)
	{
		if (t%6 == 0)
			F_PROFILE(f, thread, position) = 0.0;
		else
			F_PROFILE(f, thread, position) = .000125*sin((2*M_PI*(t%6))/5);
	}
	end_f_loop(f, thread)
}

Hi everibody, what is the meaning of t%6? I don't understand, thank you

[AlexanderZ]

its a check if number is divisible by 6 without remainder

google operator % for C language