[anuarun]

Hello friends,
I have written the following UDF for changing the vapour density based on mixture domain temperature. I am using a mixture model for simulating two phase flow.

While interpretation, it shows
line 51: parse error
line 52: parse error
line 53: undeclared variable rho



DEFINE_PROPERTY(Vapour_density,c,t)
{
Thread *tp;
tp = THREAD_SUPER_THREAD(t); /*line 51*/
real T = C_T(c,tp); /*line 52*/
real rho; /*line 53*/
rho = (0.00329*exp(0.19039*T) - 0.05762)*1000000.0;
return p_v;
}

I cannot find any mistake in it. Is it because I have interpreted instead of compilation (it is not likely to be so)? Any help is greatly appreciated.

[AlexanderZ]

Originally Posted by anuarun

Hello friends,
I have written the following UDF for changing the vapour density based on mixture domain temperature. I am using a mixture model for simulating two phase flow.

While interpretation, it shows
line 51: parse error
line 52: parse error
line 53: undeclared variable rho



DEFINE_PROPERTY(Vapour_density,c,t)
{
Thread *tp;
tp = THREAD_SUPER_THREAD(t); /*line 51*/
real T = C_T(c,tp); /*line 52*/
real rho; /*line 53*/
rho = (0.00329*exp(0.19039*T) - 0.05762)*1000000.0;
return p_v;
}

I cannot find any mistake in it. Is it because I have interpreted instead of compilation (it is not likely to be so)? Any help is greatly appreciated.

Try this one:

DEFINE_PROPERTY(Vapour_density,c,t)
{
	Thread *tp;
        real T = C_T(c,tp);                                  /*line 52*/
	real rho;                                              /*line 53*/
        tp = THREAD_SUPER_THREAD(t);             /*line 51*/
        rho = (0.00329*exp(0.19039*T) - 0.05762)*1000000.0;
	return p_v;
}

Best regards

[anuarun]

Hi Alexanderz,

Originally Posted by AlexanderZ

Try this one:

DEFINE_PROPERTY(Vapour_density,c,t)
{
	Thread *tp;
        real T = C_T(c,tp);                                  /*line 52*/
	real rho;                                              /*line 53*/
        tp = THREAD_SUPER_THREAD(t);             /*line 51*/
        rho = (0.00329*exp(0.19039*T) - 0.05762)*1000000.0;
	return p_v;
}

Best regards

Thank you for your suggestion. I have tried this. It is getting interpreted without any problem.
Actually, I think there is no point in changing the density in incompressible formulation (Initially I had similar UDF for vapour pressure and density). I decided to keep it constant for the simulation. So I incorporated the suggested changes in the macro for vapour pressure as follows.
DEFINE_PROPERTY(Vapour_pressure,c,t)
{
Thread *tp;
real T = C_T(c,tp); /*line 52*/
real p_v; /*line 53*/
tp = THREAD_SUPER_THREAD(t); /*line 51*/
p_v = (0.00202*exp(T/4.78878) - 0.04038)*1000000.0;
return p_v;
}
One more point is that I do not know whether DEFINE_PROPERTY(Vapour_pressure,c,t) is internally invoked by Fluent the same way as it does for a property as density or viscosity. Or is there a macro specifically for vapour pressure? I could not find one.
Anyway, I am running my simulation with the modifications. I will post the result once it is complete.

[AlexanderZ]

Hello!

I do not have experience in multiphase flows simulation. However, I believe that you should choose your UDF functions as a density material property of vapour.

Best regards

[anuarun]

Hi AlexanderZ,

Originally Posted by AlexanderZ

Try this one:

DEFINE_PROPERTY(Vapour_density,c,t)
{
	Thread *tp;
        real T = C_T(c,tp);                                  /*line 52*/
	real rho;                                              /*line 53*/
        tp = THREAD_SUPER_THREAD(t);             /*line 51*/
        rho = (0.00329*exp(0.19039*T) - 0.05762)*1000000.0;
	return p_v;
}

Best regards

This one is giving error, "Received signal SIGSEGV.
Fatal error"
I will try your second suggestion. I am not quite sure how it is implemented. I will check the manual and then get back to you.