How to calculate dissipation rate in FLUENT via UDF

hsncnr · April 17, 2023, 13:34

Hi;

I want to calculate the dissipation rate in Fluent using user define function. But I am receiving below error. My UDF code is below. what is the solution for this error? thanks a lot.

Error
''BAD TERMINATION OF ONE OF YOUR APPLICATION PRECESSS
RANK 3 PID 5800 RUNNING AT DESKTOP''

UDF

''
#include "udf.h"
#include "mem.h"

DEFINE_SOURCE (new_source, c, t, ds, eqn)
{
real source;
source= 0.001*pow(C_D(c,t) ,4.6);
ds[eqn] = 0.;
return source;
}
''

Siba11 · May 15, 2023, 12:43

Hi, the ds[eqn] term will be the derivative of the source term. In your case, it won't be zero.

hsncnr · May 19, 2023, 12:35

Thank you for your reply. can ANSYS calculate the derivative of turbulence kinetic energy? I cannot find it in the ANSYS user manual. Here, C_D(c,t) is turbulence kinetic energy.

Siba11 · May 19, 2023, 12:59

Hi. You don't have to calculate the derivative of C_D(c,t). You have to calculate the derivative w.r.t C_D(c,t).

Basically, you're derivative term will be:

ds[eqn] = 0.001*4.6*pow(C_D(c,t), 3.6);

hsncnr · May 23, 2023, 02:58

Although I added to the derivation express, I get the following error.

BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
RANK 0 PID 6920 RUNNONG AT DESKTOP-
EXIT STATUS:-1 (fffffffff)

April 17, 2023, 13:34	How to calculate dissipation rate in FLUENT via UDF	#1
hsncnr New Member hasan Join Date: Apr 2023 Posts: 3 Rep Power: 3	Hi; I want to calculate the dissipation rate in Fluent using user define function. But I am receiving below error. My UDF code is below. what is the solution for this error? thanks a lot. Error ''BAD TERMINATION OF ONE OF YOUR APPLICATION PRECESSS RANK 3 PID 5800 RUNNING AT DESKTOP'' UDF '' #include "udf.h" #include "mem.h" DEFINE_SOURCE (new_source, c, t, ds, eqn) { real source; source= 0.001*pow(C_D(c,t) ,4.6); ds[eqn] = 0.; return source; } ''

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May 15, 2023, 12:43		#2
Siba11 Member Odisha Join Date: Jan 2020 Posts: 59 Rep Power: 6	Hi, the ds[eqn] term will be the derivative of the source term. In your case, it won't be zero.

May 19, 2023, 12:35		#3
hsncnr New Member hasan Join Date: Apr 2023 Posts: 3 Rep Power: 3	Thank you for your reply. can ANSYS calculate the derivative of turbulence kinetic energy? I cannot find it in the ANSYS user manual. Here, C_D(c,t) is turbulence kinetic energy.

May 19, 2023, 12:59		#4
Siba11 Member Odisha Join Date: Jan 2020 Posts: 59 Rep Power: 6	Hi. You don't have to calculate the derivative of C_D(c,t). You have to calculate the derivative w.r.t C_D(c,t). Basically, you're derivative term will be: *ds[eqn] = 0.0014.6pow(C_D(c,t), 3.6)*;

May 23, 2023, 02:58		#5
hsncnr New Member hasan Join Date: Apr 2023 Posts: 3 Rep Power: 3	Although I added to the derivation express, I get the following error. BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES RANK 0 PID 6920 RUNNONG AT DESKTOP- EXIT STATUS:-1 (fffffffff)