[cliffoi]

Dear all,
I have a question around the thin film models implemented in OpenFOAM-5.0, which I think have not changed in the latest versions of the code.
There is minimal documentation around these models and the tutorial cases are difficult to understand. The best reference I can find is

Meredith et al., A numerical model for partially-wetted flow of thin liquid films, Computational Methods in Multiphase Flow VI 239

In particular, the momentum exchange between the liquid film and gas phase seems to be very crudely modelled in the current implementation using a single drag coefficient.It seems to me that it's not really possible to properly conserve momentum on the liquid film interface with the current implementation. Could somebody please confirm this?

I am trying to model vertical annular flow, where the upward drag of the vapour core ensures that the film flows upwards too.

Can anybody give me suggestions of what developments might be needed to model this correctly? My current ideas are

• Update the liquid film turbulence model (laminar) to include the gas/liquid interface shear stress, mapped from the vapour region (region0).
• Use a mapped boundary condition for the velocity at the interface for the primary gas region, which is mapped to the liquid film surface velocity.

Thanks in advance.