Learning Forum

[Prakash Singh]

How to get area weighted avg outlet temp at a specific time using udf?

[Nilay Pedram]

Hello,
Please refer to this discussion - how to calculate avg temp at outlet?

[Prakash Singh]

Thank you.

[Prakash Singh]

How can I patch the fluid domain using UDF?  I want to patch the fluid domain with T= 300 K at t= 0 sec, and T= stored outlet temperature at t=2.1 sec. I have already written a UDF to store the outlet temp.

where t varies as follows:

real t = CURRENT_TIME;

for(;;){

        if(t<=4.2)

            break;

        t=t-4.2;

    }

Thank you.

[SRP]

Hi,

Since you've already written a UDF to store the outlet temperature, you'll need to include a conditional statement within your UDF to check the current simulation time and apply the desired temperature accordingly.

DEFINE_ADJUST macro can be used to make adjustments at every time step based on the current simulation time.

[Prakash Singh]

DEFINE_EXECUTE_AT_END(patch_temperature)
{
    Domain *d = Get_Domain(1);
    Thread *t;
    cell_t c;
    double t = CURRENT_TIME;

    // Adjusting current_time to within 4.2s periodic cycle
   for(;;)
        {
            if(t<=4.2)
                    break;
            t=t-4.2;

}

// Patching at t = 2.1 sec using stored outlet temperature
    if (fabs(current_time - 2.1) < 1e-3)  
    {
        Message("Using stored outlet temperature: %f K\n", stored_temp);

        thread_loop_c(t, d)
        {
            if (FLUID_THREAD_P(t))
            {
                begin_c_loop(c, t)
                {
                    C_T(c, t) = stored_temp;  // Use dynamically stored outlet temperature
                }
                end_c_loop(c, t)
            }
        }
        Message("Temperature patched to %f K at t = 2.1 sec\n", stored_temp);
    }

I am attempting this method. However, the issue is that I am not achieving the same outcome as I achieved by manual patching. Kindly see the attached image.

What am I doing wrong?

Thank you for taking your time to read my issue.

[Prakash Singh]

*Note: 

// Adjusting current_time to within 4.2s periodic cycle
   for(;;)
        {
            if(t<=4.2)
                    break;
            t=t-4.2;

}//

please read 't' as 'current_time' in the above code.