[Auge2009]

Hello everyone,

I'm kinda new to the usage of UDFs in ANSYS Fluent, but I've got the following problem:
I want to simulate the radiation and fluid flow in a closed room with two windows. I got the simulation running using the S2S Model. Now I want to add the solar ray tracing to my model.
I was also able to manage that and in Fluent Post I can see the sun beam moving within the room. But now I would like to define the Direct Solar Irradiation and the Diffuse Solar Irradiation with own values. I thought, I could do that by using a UDF with "DEFINE_SOLAR_INTENSITY" and doing something like this:

DEFINE_SOLAR_INTENSITY(sol_direct_int, sun_x, sun_y, sun_z, S_hour, S_minute)
{
	real intensity;

        if(S_hour = 11 && S_minute <= 15){intensity=120;}

	printf("solar-time=%f intensity=%e\n", minute, intensity);
        return intensity;
	
}

After defining and compiling this UDF and setting up the solar calculator (with a time i.e. 11:12) I close the Radiation window and get:

Error:  received a fatal signal (Segmentation fault).
Error Object: #f

What am I doing wrong? And is there another way to set the Direct Solar Irradiation for every timestep differently?
The UDF works totally fine with changing for example the wall temperature with every 5 timesteps.

I hope I could describe my problem well. Thanks for your time and your answers

[Auge2009]

Does nobody have an answer? Does anyone at least have an idea for a way to avoid this problem?

[AlexanderZ]

try this code

DEFINE_SOLAR_INTENSITY(sol_direct_int, sun_x, sun_y, sun_z, S_hour, S_minute)
{
	real intensity;

        if(S_hour == 11 && S_minute <= 15){intensity=120;}

	Message("solar-time=%f intensity=%e\n", minute, intensity);
        return intensity;
	
}

Best regards

[Morice]

Originally Posted by AlexanderZ

try this code

DEFINE_SOLAR_INTENSITY(sol_direct_int, sun_x, sun_y, sun_z, S_hour, S_minute)
{
	real intensity;

        if(S_hour == 11 && S_minute <= 15){intensity=120;}

	Message("solar-time=%f intensity=%e\n", minute, intensity);
        return intensity;
	
}

Best regards

I know this is an old thread but please bear with me

Was this UDF able to work for anyone who tried to implement it this way?

I keep getting an error message, the screenshot is attached.

My UDF simply defines the intensity values.

#include "udf.h"

DEFINE_SOLAR_INTENSITY(sol_direct_intensity,sun_x, sun_y,sun_z,hour,minute)
{
real intensity;
intensity = 35;
Message("solar-time=%f intensity=%e\n", minute, intensity);
return intensity;
}

DEFINE_SOLAR_INTENSITY(sol_diffuse_intensity,sun_x ,sun_y,sun_z,hour,minute)
{
real intensity;
intensity = 77;
Message("solar-time=%f intensity-diff=%e\n", minute, intensity);
return intensity;
}

[vinerm]

You appear to be interpreting the library while you need to compile it. If you do not have a compiler then remove Message command. Rest of the code will work.

[Morice]

Originally Posted by vinerm

You appear to be interpreting the library while you need to compile it. If you do not have a compiler then remove Message command. Rest of the code will work.

When I tried compiling it, I kept getting the "n-make" error and the UDF library not compiled for parallel use. That is the reason I tried to interpret it instead.

Even with the VS installed, the error still persists but I found I workaround on youtube of using the x86_x64 Cross Tools command prompt in VS.

Thanks for the response

[vinerm]

Just the installation of VS or Build Tools is not sufficient. Either you need to ensure that udf.bat file installed with Fluent has correct path or use any of the VS command prompts to start Fluent. Once compiled, it will work with normally started Fluent as long as you use the library for same OS, same precision, and same mode (serial or parallel).

[Morice]

Morning Vinerm,

Thanks for the response.

Yes you are right. I used the VS x86_x64 Command Prompt in VS to start FlUENT and the UDFs compiled successful.

I was able to run the simulation as well.

Thank you for your assistance. much appreciated