The Thin-Film and Porous Media Flow Interface
The Thin-Film and Porous Media Flow interface () combines the Thin-Film Flow interface with the Darcy’s Law interface. It couples the flow of a thin film of fluid in a channel, represented by a boundary in the geometry, with a low velocity fluid flow in a porous medium, represented by a domain in the geometry.
When a predefined Thin-Film and Porous Media Flow interface is added from Porous Media and Subsurface Flow branch () of the Model Wizard or Add Physics window, Thin-Film Flow and Darcy’s Law interfaces are added to the Model Builder. In addition, the Multiphysics node is added, which automatically includes the Thin-Film and Porous Media Flow multiphysics coupling.
On the Constituent Physics Interfaces
The Thin-Film Flow interface is used to solve the Reynolds equation or the modified Reynolds equation in a narrow channel that is represented by a boundary within the geometry. It is used for lubrication, elastohydrodynamics, or gas damping simulations when the fluid channel is thin enough for the Reynolds equation or the modified Reynolds equation to apply.
The Darcy’s Law interface is used to simulate fluid flow through interstices in a porous medium. It can be used to model low-velocity flows or media where the permeability and porosity are very small, and for which the pressure gradient is the major driving force and the flow is mostly influenced by the frictional resistance within the pores.
Settings for Physics Interfaces and Coupling Features
When physics interfaces are added using the predefined coupling, for example Thin-Film and Porous Media Flow, specific settings are included with the physics interfaces and the coupling features.
However, if physics interfaces are added one at a time, followed by the coupling feature, these modified settings are not automatically included.
For example, if single Thin-Film Flow and Darcy’s Law interfaces are added, an empty Multiphysics node appears in the model tree. You can choose from the available coupling features but the settings in the constituent interfaces are not modified.