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 Emmanuel December 8, 2006 07:57

UDF for Square Wave

Hi,

How can I write a simple UDF for a square wave.

Frequency is 220hz

Mean value is 15.59psi

Amplitude is 0.89psi

I want to compare a square wave with my sinusoidal wave.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

#include "udf.h"

float t, pressure; face_t f;

t = RP_Get_Real("flow-time");

pressure = (15.59+(0.89*sin(220*6.283185307*t)))*6894.757;

}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

 Phil December 9, 2006 14:49

Re: UDF for Square Wave

I did this at one time. I used a cycle fraction to define when to switch from the positive side of the cycle to negative side.
Calculate cycle fraction as cycle fraction = t/T
where t= flow time and T=time period (1/220)
then use this simple code in place of your last line.

CODE:

{
if (cyc_frac < 0.5)
{
}
else
{
}
}

Hope this helps,
Phil

 mahbube March 13, 2010 09:36

question

Quote:
 Originally Posted by Emmanuel ;137486 Hi, How can I write a simple UDF for a square wave. Frequency is 220hz Mean value is 15.59psi Amplitude is 0.89psi I want to compare a square wave with my sinusoidal wave. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% #include "udf.h" DEFINE_PROFILE(unsteady_pressure, thread, position) { float t, pressure; face_t f; t = RP_Get_Real("flow-time"); pressure = (15.59+(0.89*sin(220*6.283185307*t)))*6894.757; begin_f_loop(f, thread) { F_PROFILE(f, thread, position) = pressure; } end_f_loop(f, thread) } %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
hi,
would you please say me how you write pressure equation for sinusoidal wave?could you send/give or/and even introduce me some references

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