phase field or Cahn-Hilliard method
 

Is anyone familar with the method of phase field or Cahn-Hilliard? Could you tell me what is Mobility and and how to find the number for specific fluid, such like water. I read two paper, one set 1, another is quite small.

In addition, I can not understand why the Helmoltz free energy can be difined as F(c)=c**2(c-1)**2, here c is the concentration

Thanks a lot

He

Re: phase field or Cahn-Hilliard method
 

Could you specify what kind of problem you want to solve? phase separation or just interfacial flow between two immiscible fluids?

Pete

Re: phase field or Cahn-Hilliard method
 

I want to simulate the liquid-vapor two-phase flow. The problem is how to solve the sigularity of contact line. I adopted the Navier slip boundary, but it seems unsuited for my case for there was significant bulk velocity and the slip velocity was not matched to the bulk velocity. So I want to use phase-field method, it is reported that it can simulate the contact line movement naturally.

I read the papers by Prof.Jamet and Dr Kim. I can understand some of them, but I do not know how to relate the parameters, such like Mobility, Free energy etc., to the real working fluid, say water and gas.

Re: phase field or Cahn-Hilliard method
 

You may consider the phase-field method as a computational tool, then Mobility works for the relaxation of the interface profile just like reinitialization of level set in level-set method. Free energy forces two phase separated.

So, the bottom line is, we want Mobility as small as possible.