[romanpicisan]

Hi, I am working on a UDF to mimic a daily water flow in pipe for a year period. Water will start flowing from 9:00 am (32400 s + 86400 x day) until 6:00 pm (64800 s + 86400 x day) daily at a velocity of 0.0562 m/s. A velocity ramp in a period of 10 s will be given before start-up and after shut-down of the flow.

The plot (unfinished) of the intended scheme would somewhat look like the attached photo, which was obtained using a UDF by manually inserting the values in the conditions/statements (about 4000 lines). With the help of a spreadsheet to write the lines, it was still manageable.

However, I would like to have a UDF that is simple and robust. I had tried numerous UDF but to no avail. The most promising one that I could come up with is as follows.

I would appreciate if someone can assist me on this. Thanks.

#include "udf.h"

DEFINE_PROFILE(discontinuous_1y,x,i)
{
int t = CURRENT_TIME;
face_t f;
real off = 0, on = 0.0562; //velocity during no-flow and flow
real ramp = 10, v; //ramp time 10 s before flow and after flow is given
real slope = on/ramp; //slope used during ramp time
int start, stop;
int *time;
time = &t;

if(t < 86400) //1 day equals 86400 s
{
if(*time % 86400 == 64800) //9:00 am day-0
start = *time;
else if(*time % 86400 == 43200) //6:00 pm day-0
stop = *time;
}
else
{
if(*time % 86400 == 32400) //9:00 am day-i
start = *time;
else if(*time % 86400 == 64800) //6:00 pm day-i
stop = *time;
}

begin_f_loop(f,x)
{
if(t <= 32400)
v = off;
else if(t <= (start + ramp) && t > start)
v = slope * (t - start);
else if(t <= stop && t > (start + ramp))
v = on;
else if(t <= (stop + ramp) && t > stop)
v = on - slope * (t - stop);
else
v = off;
F_PROFILE(f,x,i) = v;
}
end_f_loop(f,x)
}

DEFINE_DELTAT(deltat_1y,d)
{
int t = CURRENT_TIME;
real tstep, off = 5399, on = 3239, up = 10, down = 2; //time step values
real ramp = 10;
int start;
int stop;
int *time;
time = &t;

if(t < 86400)
{
if(*time % 86400 == 64800)
start = *time;
else if(*time % 86400 == 43200)
stop = *time;
}
else
{
if(*time % 86400 == 32400)
start = *time;
else if(*time % 86400 == 64800)
stop = *time;
}

if(t < 32400)
tstep = 3600;
else if(t < (start + ramp) && t >= start)
tstep = up;
else if(t < stop && t >= (start + ramp))
tstep = on;
else if(t < (stop + ramp) && t >= stop)
tstep = down;
else
tstep = off;
return tstep;
}