[nsaeidi]

Hello everyone!


I am trying to apply a time-varying temperature boundary condition to the inlet boundary of my porous zone geometry by reading the temperature values from a data file (.txt). My C file and the text file that I read from are attached.


After I compile the UDF and Hook the read_data function, this message shows up in Console: “temperature limited to 1.000000e+00 in 141630 cells on zone 4”
Zone 4 is my porous zone. My temperature limit setting is from 1K to 5000K.
I don’t face this problem when I set constant inlet BC or when I don’t have a read_data function in the UDF.

Does anybody have any idea what could be the problem?

[nsaeidi]

I tried to make the meshing finer but I still received the same notice except with larger number of cells on the porous zone ( 192779 instead of 141630, mesh is denser)!

Please share your thinking with me ...

[pakk]

Try to print the temperature to see if it is read in the way that you intended:

DEFINE_PROFILE(Tinlet, thread, position) 
{
  face_t f;
  real t = CURRENT_TIME*pow(1,-1);
  int i = t;

  begin_f_loop(f, thread)
    {   
      F_PROFILE(f, thread, position) = Temp[i];
    }
  end_f_loop(f, thread)
  Message("Temp = %f\n",Temp[i]);
}

Then look at the Text user Interface to see what is shown there. That might give you an idea on what is going on.

[nsaeidi]

I tried! It doesn't read it correctly. It lists out only Temp = 0.000000 in the TUI.

[pakk]

And the following?

Message("t=%f, i=%d, Temp = %f\n",t,i,Temp[i]);

Did you hook the read_data function?

[nsaeidi]

Yes I did Hook the read-data function.
It prints t=0.000000, i=0, Temp = 0.000000
So it doesn't go trough the loop at all! right?

[pakk]

I think the problem is in your read_data.

In the following line:

fscanf(fp,"%ld", &Temp[i]);

You read a long integer (%ld), but you store it in a double (Temp was previously defined as double).

Maybe:

fscanf(fp,"%f", &Temp[i]);
Message("Read: %f\n",Temp[i]);

The second line is just to directly show what you read, if everything works you can remove it.

[nsaeidi]

It is still same as before
it shows Read: 0.000000 for Message("Read: %f\n",Temp[i]);
and t=0.000000, i=0, Temp = 0.000000 for Message("t=%f, i=%d, Temp = %f\n",t,i,Temp[i]);

I don't understand what is the problem ? because my code works if I introduce Temp[i] as a function of time rather than using DEFINE_INIT(read_data, d) application.

[pakk]

The problem is in your read_data.
You are not reading the file properly. So of course it works if you skip this step and put the data directly in the sourcefile...

You see:

Read: 0.000000

That means that nothing is read (since 0.00000 is the default value).

You defined TEMP as a double, so you have to read it as a double.

I don't remember exactly the code to do this, google for it. My next guess would be this:

fscanf(fp,"%lf", &Temp[i]);

But if that also gives 0.0000 as temperature, you need a different format, so google for fscanf to see how to properly read a double.

[nsaeidi]

You were right!
Problem Solved!
Thank you so much!

[pakk]

Nice.

[gouravjee]

Originally Posted by pakk

Try to print the temperature to see if it is read in the way that you intended:

DEFINE_PROFILE(Tinlet, thread, position) 
{
  face_t f;
  real t = CURRENT_TIME*pow(1,-1);
  int i = t;

  begin_f_loop(f, thread)
    {   
      F_PROFILE(f, thread, position) = Temp[i];
    }
  end_f_loop(f, thread)
  Message("Temp = %f\n",Temp[i]);
}

Then look at the Text user Interface to see what is shown there. That might give you an idea on what is going on.

Hii All,
I have been working on a heat exchanger problem in which the molten metal kept stationary in outer shell of a concentric tube and a fluid is flowing in the inner tube.
I am using UDS scalars to define temperature and velocity but results do not show any variation in temperature profile of fluid part(even if flow is there) and remains same as the stationary fluid
kindly provide me some hint regarding this problem

Thanks in Advance