[Imane]

Hello everyone,
I am beginner in fluent v15, and I want to simulate the temperature change as a function of time in the phase change materials "PCM" and the heat thermal fluid "HTF" and the PCM fusion Front.
Regarding the geometry I chose to work with two coaxial tubes: the inner tube contains the heat thermal fluid and the outer tube contains the PCM
for meshing I appointed the input, output and symmetry area of ​​HTF and PCM. Also the entry, exit and the symmetry of the wall between the PCM and the HTF
The set up steps followed are:
General ==> Type: based pressure, velocity formulation: absolute, time: transient
Model ==> volume of fluid with 2 stages in number eulerian, energy, melting and solidification
Materials ==> PCM characteristics: density, solidius and liquidus temperature , thermal conductivity, pure solvent latent heat and thermal expansion coefficient
for the HTF I chose to work with liquid water
Phases ==> Primary phase pcm, Secondary phase HTF
Cell Condition box ==> Wall (phase mixture, Type: Solid)
HTF (phase mixture type: Fluid, Fluid porosity: 1)
PCM (phase mixture type: Fluid, Fluid porosity: 1)
NB: I want to determine the porosity of the fluid depending on the temperature f (T)
- f(T) = 0 if T < Ts
- f(T) = 1 if T > Tm
- 0 < f(T) = (T -Ts) / (Tm - Ts ) < 1 if Ts < T < Tm
but I don't know how to do it with new input parameter
Boundary Conditions ==> in this stage I entered the HTF input velocity and the inlet and outlet temperatures of the HTF, PCM and WALL but I find myself stuck facing problem with the symmetry area of HTF and PCM.
and other boundary conditions appear as: wall-htf-wall, wall-htf-shadow-wall, wall-pcm, wall-pcm-wall, wall-pcm shadow-wall, wall-wall
but I do not know what to choose for thermal conditions: temperature convection heat flow or or ...
and if for example I chose the heat flux how can I calculate the heat generation rate and the heat flux.

I will be very grateful for your help and thank you in advance.

Best regards;