[hemmt]

Hello every one,

I have velocity profile (atmospheric boundary layer) data for each time step, (means X coordinate, Y coordinate, Z coordinate ,time, X velocity, Y Velocity, Z velocity) saved as .csv format.
I need to use this file as inlet boundary condition for each time step in FLUENT.

So please suggest me suitable macros to read data file as inlet boundary condition at each time step.


Thanks

[sh.a.ghafour]

Dear hemmt,
you can use a profile in a notepad file but save it with extension .PROF (i begin with excel sheet and copy it to a notpad file then save it with the required extension)
or use can make a udf with DEFINE_PROFILE macro
good luck

[sh.a.ghafour]

an example from my work
example.txt

[LuckyTran]

I would also suggest to make a profile table since you already have it in a table (although it's in a csv).

[hemmt]

Originally Posted by sh.a.ghafour

Dear hemmt,
you can use a profile in a notepad file but save it with extension .PROF (i begin with excel sheet and copy it to a notpad file then save it with the required extension)
or use can make a udf with DEFINE_PROFILE macro
good luck

hello sir, Thanks for ur reply.
Actually I new to Fluent UDF.
Can u Provide me an example of UDF for using profile data(Atmospheric boundary layer)

Thanks

[macfly]

Originally Posted by sh.a.ghafour

an example from my work
Attachment 51119

Your example doesn't answer the initial question because it doesn't have x-y-z coordinates.

Anybody knows how to write a transient profile .prof that contains x-y-z coordinates? The coordinates should be written only once, and then all the corresponding values for each time step... I didn't find any example like that.

[yousefaz]

Originally Posted by macfly

Your example doesn't answer the initial question because it doesn't have x-y-z coordinates.

Anybody knows how to write a transient profile .prof that contains x-y-z coordinates? The coordinates should be written only once, and then all the corresponding values for each time step... I didn't find any example like that.

Macfly,

Unfortunately, I don't think that is possible even with the latest version of fluent. If I have read the Fluent manual correctly, the transient boundary profiles in fluent must be spatially uniform: https://www.sharcnet.ca/Software/Ans...transient.html

It seems there is no apparent way of specifying profile that varies with both time and space with a .prof or a .ttab file.

I am currently struggling with the same problem myself. Basically, I have a MATLAB code that generates velocity vs time data for the inlet surface (spatially and temporally non uniform) that I am not able to import into fluent with the profile tool. The only way this seems possible is with a UDF function that reads data from the csv file, and updates the profile with each time-step. For my case, it makes more sense to rewrite the MATLAB code as a UDF.

[hemmt]

Originally Posted by yousefaz

Macfly,

Unfortunately, I don't think that is possible even with the latest version of fluent. If I have read the Fluent manual correctly, the transient boundary profiles in fluent must be spatially uniform: https://www.sharcnet.ca/Software/Ans...transient.html

It seems there is no apparent way of specifying profile that varies with both time and space with a .prof or a .ttab file.

I am currently struggling with the same problem myself. Basically, I have a MATLAB code that generates velocity vs time data for the inlet surface (spatially and temporally non uniform) that I am not able to import into fluent with the profile tool. The only way this seems possible is with a UDF function that reads data from the csv file, and updates the profile with each time-step. For my case, it makes more sense to rewrite the MATLAB code as a UDF.

please share the solution regarding this means udf to read this velocity profile and update at each time step.

[macfly]

Originally Posted by yousefaz

Unfortunately, I don't think that is possible even with the latest version of fluent. If I have read the Fluent manual correctly, the transient boundary profiles in fluent must be spatially uniform: https://www.sharcnet.ca/Software/Ans...transient.html

I read that too, I was trying to see if someone had maybe pushed the enveloped further.

Originally Posted by yousefaz

I am currently struggling with the same problem myself. Basically, I have a MATLAB code that generates velocity vs time data for the inlet surface (spatially and temporally non uniform) that I am not able to import into fluent with the profile tool. The only way this seems possible is with a UDF function that reads data from the csv file, and updates the profile with each time-step. For my case, it makes more sense to rewrite the MATLAB code as a UDF.

It's easy to generate profile files for each time step. You don't need a udf to read a new profile file every time step, it can be programmed easily in the 'Execute Commands'. But it's kinda stupid because each profile file has the exact same coordinates data.. and when the mesh is fine and there is a lot of time steps, you end up with many useless GBs of useless coordinates on your hard disk and it slows the solver because it has to load a large profile file at each time step..

[yousefaz]

Originally Posted by macfly

It's easy to generate profile files for each time step. You don't need a udf to read a new profile file every time step, it can be programmed easily in the 'Execute Commands'. But it's kinda stupid because each profile file has the exact same coordinates data.. and when the mesh is fine and there is a lot of time steps, you end up with many useless GBs of useless coordinates on your hard disk and it slows the solver because it has to load a large profile file at each time step..

Thanks for the tip! It seems so trivial now that you mention it.
I agree this method is far from perfect, but it saves me a lot of time at least for the initial stages of my project. I suspect that eventually I'll have to bite the bullet and write the UDF.

[macfly]

yousefaz, here is a Execute Commands example where your profile files would be named, for example,
profile-0001.prof
profile-0002.prof
profile-0003.prof
and so on...

(ti-menu-load-string (format #f "file read-profile profile-~04d.prof" (rpgetvar 'flow-time)))

[yousefaz]

Much appreciated Macfly!

Hemmt,

With regards to the UDF, here is a script I found that reads data from a text file into a c++ array: (https://www.researchgate.net/post/Ca..._in_LES_FLUENT)

I will update you if I ever get around to writing the full UDF.

#include "udf.h"
#include "stdio.h"
#include "stdlib.h"
#include "math.h"

FILE * coeff;
float var1[10000]={0},var2[10000]={0},var3[10000]={0};
int count;

DEFINE_ON_DEMAND(get_data)
{
coeff = fopen("file.txt", "r");
if (coeff == NULL)
exit(EXIT_FAILURE);

count=0;
#if RP_HOST
Message("Reading Data");
#endif
while (!feof(coeff)) /* reading columns with tabs between them */
{
fscanf(coeff,"%f %f %f",&var1[count], &var2[count], &var3[count]);
count++;
}
#if RP_HOST
Message("End of reading");
#endif
fclose(coeff);
}

[hemmt]

Originally Posted by yousefaz

Much appreciated Macfly!

Hemmt,

With regards to the UDF, here is a script I found that reads data from a text file into a c++ array: (https://www.researchgate.net/post/Ca..._in_LES_FLUENT)

I will update you if I ever get around to writing the full UDF.

#include "udf.h"
#include "stdio.h"
#include "stdlib.h"
#include "math.h"

FILE * coeff;
float var1[10000]={0},var2[10000]={0},var3[10000]={0};
int count;

DEFINE_ON_DEMAND(get_data)
{
coeff = fopen("file.txt", "r");
if (coeff == NULL)
exit(EXIT_FAILURE);

count=0;
#if RP_HOST
Message("Reading Data");
#endif
while (!feof(coeff)) /* reading columns with tabs between them */
{
fscanf(coeff,"%f %f %f",&var1[count], &var2[count], &var3[count]);
count++;
}
#if RP_HOST
Message("End of reading");
#endif
fclose(coeff);
}

Dear sir
thanks for Your kind reply

Could you help me to for full UDF regarding to read transient ABL data

Thanks