Help! How to get the gradient of void fraction?
 

Hello, I use Eulerian multiphase model in FLUENT (version 6. 3.33)and tried to get the gradient of the void fraction. I found someone had the same problem before and tried his method:
if (NULL != THREAD_STORAGE(thread,SV_VOF_G))
{v_s = C_VOF_G(cell, thread)[0];}
But it did not work!!!!!!!!!!! I checked the THREAD_STORAGE, it is always == NULL.
Does anyone have some idea how to get it? Any suggestion is appreciated.

Hi friends,
I'm simulating a tube with water flow.
The tube encounters boiling near the wall.
I intend to calculate 'void fraction versus enthalpy' along the channel.
Can you help me how to calculate void fraction?

I'm in an emergency condition.
Waiting for your comments!!!

Thanks Everybody