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Struggling with if-else statement in UDF

Hi I am writing for udf pulsed laser source. But I got problem with changing the velocity(it needs to be 0 when heating and become 1 when waiting time). So I discrete my code understand that origin of problem. So I seperated if statement for source and velocity. If statement for source is working very well. But if statement for vel has a problem. The "else" part is working when condition met but for if part it uses the predefined(0.0) value.

Code:

#include "udf.h"



DEFINE_SOURCE(Goldak7, cell, thread, dS, eqn)

{

real x[ND_ND];

real current_time;

real LayerThickness = 0.00005;

real LaserSpotRadii = 0.000075;

real K = -3.0;

real F = 0.6;

real Q = 2000;

real vel = 0.0;

real x0 = 0.0;

real PI = acos(-1);

real KGoldak;

real x_pos;

real source;

current_time = CURRENT_TIME;

KGoldak = (6 * sqrt(3) * F * Q) / (LaserSpotRadii * LaserSpotRadii * LayerThickness * PI *sqrt(PI));    



C_CENTROID(x, cell, thread);



if ( current_time > 0.01)

{

vel = 0.99;

}

else

{

vel = 0.1;

}



x_pos = vel * current_time;



if ( current_time > 0.01)

{

source  = KGoldak*exp(K*(pow((x[0] - x_pos),2.)/pow(LaserSpotRadii,2.) +  pow(x[1],2.)/pow(LaserSpotRadii,2.) + pow(x[2],2.) /  pow(LayerThickness,2.)));

dS[eqn] = 0.0;

}

else

{

source =  KGoldak*exp(K*(pow((x[0] - x_pos),2.)/pow(LaserSpotRadii,2.) +  pow(x[1],2.)/pow(LaserSpotRadii,2.) + pow(x[2],2.) /  pow(LayerThickness,2.)));

dS[eqn] = 0.0;

}

return source;

}

I am struggling this code for 3 days. I will be really appreciate if you can help.
P.S; I notice while writing this post, I can use initial value like if condition value. But still I am wandering where is my mistake

vel = 0.1 for time 0 -> 0.01
vel = 0.99 after that
code is correct

your statements for sources are identical, so you don't really need if statement there

Ah I understand what you mean and thx for help. sorry I was made a lot of change and the second part will be zero.
And also I solved half of my problem. Vel is changing but x_pos still become 0 because of calculation. So I made changes and improvements however while it compiled without problem "x_pos = x_pos + displacement;" line didn't work properly;

Code:

#include "udf.h"

#include "math.h"



real x[ND_ND];

real current_time;

real timestep;

real LaserSpotRadii = 0.000075; 

real LayerThickness = 0.00005;

real K = -3.0;

real F = 0.6;



real Q = 600;

real x0 = 0.0;



real pulse_time = 0.006;

real period = 0.008;

real KGoldak;

real vel = 0.0;

static real x_pos = 0.0;

real source = 0.0;

real displacement = 0.0;



DEFINE_SOURCE(PulsedLaser, cell, thread, dS, eqn)

{

real PI = acos(-1);

current_time = CURRENT_TIME;

timestep = CURRENT_TIMESTEP;

KGoldak = (6 * sqrt(3) * F * Q) / (LaserSpotRadii * LaserSpotRadii * LayerThickness * PI *sqrt(PI));



C_CENTROID(x, cell, thread);



if (fmod(current_time, period) < pulse_time)

{

vel = 0.0;

displacement = vel * timestep;

x_pos = x_pos + displacement;

}

else

{

vel = 0.2;

displacement = vel * timestep;

x_pos = x_pos + displacement;

}



if (fmod(current_time, period) < pulse_time)

{

source= KGoldak*exp(K*(pow((x[0]-x_pos),2.)/pow(LaserSpotRadii,2.) + pow(x[1],2.)/pow(LaserSpotRadii,2.) + pow(x[2],2.) / pow(LayerThickness,2.)));

dS[eqn] = 0.0;

}

else

{

source = 0.0;

dS[eqn] = 0.0;

}

return source;

}

Code:

static real x_pos = 0.0;

why is it static?

Because of the following part of code, it is incremental and need to change every timestep.

Code:

vel = 0.0;

displacement = vel * timestep;

 x_pos = x_pos + displacement

I solved now with execute at end macro. I get that hint from your answers in another problem thread. Thanks AlexanderZ:D:D