[priyanka.asp]

Hello all,

I am new to fluent and I want to use a UDF for defining the granualar viscosity of the secondary phase in the mixture model :
mu= -0.188 + 537.42*Volume fraction.

I had written the follwoing UDF.

#include "udf.h"
DEFINE_PROPERTY(solid_viscosity,cell, thread)
{
real mu;
real vf=C_T(cell,thread);
mu=-0.188+537.42*vf;
return mu;
}

This is correct? And how can I use this in my case. Can anyone help?

Thanks

[Siddiqui]

I think you need to use DEFINE_ADJUST macros to modify the volume fraction using C_VOF(cell,thread)*constant; save this in user defined memory then use this User defined memory in DEFINE_PROPERTY macro like mu=C_UDMI(cell,thread,i).

[souza.emer]

Hello,

I'm new with Fluent and with UDF, and in my case, I have to modify my secondary thermal conductivity with the formula:

k = (-0.76 + 0.0063*T)*alfa

with:

T = secondary phase temperature
alfa = secondary phase volume fraction

Is this UDF written properly?

#include "udf.h"

DEFINE_PROPERTY(k_coke, c, t)
{
real k_c;
real temp = C_T(c, t);
real vf_c = C_VOF(c, t);

k_c = (-0.76 + 0.0063*temp)*vf_c;

return k_c;
}

My doubt is if I'm taking the secondary variables (volume fraction and temperature) correctly. Can anyone help me?

[prakash.singh]

Originally Posted by priyanka.asp

Hello all,

I am new to fluent and I want to use a UDF for defining the granualar viscosity of the secondary phase in the mixture model :
mu= -0.188 + 537.42*Volume fraction.

I had written the follwoing UDF.

#include "udf.h"
DEFINE_PROPERTY(solid_viscosity,cell, thread)
{
real mu;
real vf=C_T(cell,thread);
mu=-0.188+537.42*vf;
return mu;
}

This is correct? And how can I use this in my case. Can anyone help?

Thanks

Can you help me with the granular viscosity, how did you find granular viscosity and solid pressure and other properties?

[souza.emer]

Granular Vicosity and granular solids pressure Macro = DEFINE_PROPERTY

[prakash.singh]

Originally Posted by souza.emer

Granular Vicosity and granular solids pressure Macro = DEFINE_PROPERTY

I don't know any equation to calculate granular viscosity. Is there some empirical relation that I can use?

[souza.emer]

Have you take a look at the theory guide? There you can find the equation for each model that Fluent provides.

[prakash.singh]

Originally Posted by souza.emer

Have you take a look at the theory guide? There you can find the equation for each model that Fluent provides.

Yes, I have. I have come across two equations, one for collisional viscosity and other one is for kinetic viscosity.