Discussion Forum

Hi.

I am attempting to simulate the sublimation behavior/equilibrium point of ice in a closed container.

In summary I have modeled the problem as a fluid/heat transfer model which builds up pressure via sublimation to a certain limit in a CLOSED container (i.e. a model with an inlet but without outlet) where the interface is modeled as a mass flow inlet controlled by a analytic formula (hertz-knudsen equation) based on the temperature and pressure inside the chamber. The objective is to find the equilibrium point (m_dot(T,p) at inlet = 0), but it seems as though COMSOL is not able to handle this problem in a natural way. All modules I can find are based on Navier Stokes, which is more a simulation of the flow of fluids and might not be ideal for this problem. The problem is that the outlet is also meant to be controllable (via for example a valve) and the flow equations are needed whenever the outlet flow is not = 0, in order to visualize the flow.

I attempted a first model based on freeze drying, but this is not really valid in this case because it only handles diffusion and not the spread of water vapor (steam) in an absolute vacuum. In the container there really is only one chemical species (i.e. water).

Does anyone have experience of a similar problem or tips on how to handle such a problem in COMSOL?

Regards,
Rasmus