Concentration dependent surface tension
 

hello,

i want so specify surface tension as a function of concentration in the liquid phase.
the liquid phase has two species and i´m using VOF multiphase model.

so which thread is the t - thread in the define_property macro ?

with DEFINE_PROPERTY(surface_tension,c,t) and C_YI(c,t,0) fluent shows an access violation error
with several multiphase macros like thread_sub_threads... fluent shows the same error

please help
thx

i still have this problem :(
can anyone help me or give a suggestion ?
thanks a lot

Hey there anyone it may help. I know this reply is late, but this post helped me on my journey and I would like to answer.

I have the same objective as this post states, to write a UDF that controls the surface tension coefficient by analyzing the mixture species fraction.

The following code seems to be the answer:


DEFINE_PROPERTY(Custom_Surface_Tension, c, t)
{
Domain *mix;
mix = Get_Domain(1);

Thread *mix_thread = Lookup_Thread(mix, 2);
Thread *sec_phase = THREAD_SUB_THREAD(mix_thread,1);

real sigma, xm;

xm = C_YI(c,sec_phase,1);
sigma = 0.043*xm*xm - 0.1081*xm + 0.0702;


return sigma;
}


The key part being the first 4 lines of code:
Lines 1-2. grab the mixture domain pointer (domain ID=1 for mixture domain) & assign variable *mix.
Line 3. Find the relevant thread (domain ID=1 for mixture, Zone ID=2 for fluid), assign the lookup to a variable *mix_thread (this is a mixture level thread)

Line 4. Assign a phase level pointer (*sec_phase) to secondary phase thread



*sec_phase now has the required data to proceed with mass fraction function C_YI