Pressure variation UDF
 

Hi guys,
I am trying to create a pressure variation with time UDF for the walls of my tank. I will also try to do the same with temperature but I wrote a code for pressure first and I am not sure whether its correct

Its a little long because for each time I have a different pressure


/************************************************** *******************************************/
/*UDF for specifying the pressure variation with time for the conditions surrounding the tank*/
/************************************************** *******************************************/



#include "udf.h"

DEFINE_PROFILE(pressure.profile,t,i)
{
face_t f;
begin_f_loop(f,thread)
{
time=0
F_PROFILE(f,thread,i)=100000
time=20
F_PROFILE(f,thread,i)=98656.6667
time=40
F_PROFILE(f,thread,i)=97313.33333
time=60
F_PROFILE(f,thread,i)=95970
time=80
F_PROFILE(f,thread,i)=94626.66667
time=100
F_PROFILE(f,thread,i)=93283.33333
time=120
F_PROFILE(f,thread,i)=91940
time=140
F_PROFILE(f,thread,i)=90596.66667
time=160
F_PROFILE(f,thread,i)=89253.33333
time=180
F_PROFILE(f,thread,i)=87910
time=200
F_PROFILE(f,thread,i)=86566.66667
time=220
F_PROFILE(f,thread,i)=85223.33333
time=240
F_PROFILE(f,thread,i)=83880
time=260
F_PROFILE(f,thread,i)=82536.66667
time=280
F_PROFILE(f,thread,i)=81193.33333
time=300
F_PROFILE(f,thread,i)=79850
time=320
F_PROFILE(f,thread,i)=78506.66667
time=340
F_PROFILE(f,thread,i)=77163.33333
time=360
F_PROFILE(f,thread,i)=75820
time=380
F_PROFILE(f,thread,i)=74476.66667
time=400
F_PROFILE(f,thread,i)=73133.33333
time=420
F_PROFILE(f,thread,i)=71790
time=440
F_PROFILE(f,thread,i)=70446
time=460
F_PROFILE(f,thread,i)=69103.33
time=480
F_PROFILE(f,thread,i)=67760
time=500
F_PROFILE(f,thread,i)=66416
time=520
F_PROFILE(f,thread,i)=65073
time=540
F_PROFILE(f,thread,i)=63730
time=560
F_PROFILE(f,thread,i)=62386.667
time=580
F_PROFILE(f,thread,i)=61043.33
time=600
F_PROFILE(f,thread,i)=59700
time=620
F_PROFILE(f,thread,i)=58356
time=640
F_PROFILE(f,thread,i)=57013.33
time=660
F_PROFILE(f,thread,i)=55670
time=680
F_PROFILE(f,thread,i)=54326
time=700
F_PROFILE(f,thread,i)=52983.6667
time=720
F_PROFILE(f,thread,i)=51640
time=740
F_PROFILE(f,thread,i)=50296.667
time=760
F_PROFILE(f,thread,i)=48953
time=780
F_PROFILE(f,thread,i)=47610
time=800
F_PROFILE(f,thread,i)=46266.6667
time=820
F_PROFILE(f,thread,i)=44923.333
time=840
F_PROFILE(f,thread,i)=43580
time=860
F_PROFILE(f,thread,i)=42236.667
time=880
F_PROFILE(f,thread,i)=40893.333
time=900
F_PROFILE(f,thread,i)=39550
time=920
F_PROFILE(f,thread,i)=38206.6667
time=940
F_PROFILE(f,thread,i)=36863.333
time=960
F_PROFILE(f,thread,i)=35520
time=980
F_PROFILE(f,thread,i)=34176.6667
time=1000
F_PROFILE(f,thread,i)=32833.333
time=1020
F_PROFILE(f,thread,i)=31490
time=1040
F_PROFILE(f,thread,i)=30146
time=1060
F_PROFILE(f,thread,i)=28803.33
time=1080
F_PROFILE(f,thread,i)=27460
time=1100
F_PROFILE(f,thread,i)=26116.6667
time=1120
F_PROFILE(f,thread,i)=24773.333
time=1140
F_PROFILE(f,thread,i)=23430
time=1160
F_PROFILE(f,thread,i)=22086.6667

if ( 27580> t >1160)
F_PROFILE(f,thread,i)=19400
}

From Ansys Fluent UDF Manual 15.0:

2.3.19.11. Example 9 - Mass Flow Rate UDF for the Mass Flow Inlet
This UDF is used to provide a time-varying specification of the mass flow rate. This boundary condition can be applied using a DEFINE_PROFILE UDF.....


#include "udf.h"
DEFINE_PROFILE(inlet_mf,th,i)
{
face_t f;
begin_f_loop(f,th)
{
if(CURRENT_TIME <= 0.01)
F_PROFILE(f,th,i) = 3.0;
else if(CURRENT_TIME <=0.02 && CURRENT_TIME >0.01)
F_PROFILE(f,th,i) = 4.0;
else
F_PROFILE(f,th,i) = 5.0;
}
end_f_loop(f,th);
}



You just have to do a bunch of else if!

Next time, ask on the UDF forum please: http://www.cfd-online.com/Forums/fluent-udf/