Subsurface Flow Module Updates
For users of the Subsurface Flow Module, COMSOL Multiphysics® version 5.2a brings a new Poroelasticity interface, Gravity feature, and Flownet plot type. Review all of the Subsurface Flow Module updates in detail below.
New Poroelasticity Interface
There is a new Poroelasticity multiphysics coupling between Solid Mechanics and Darcy’s Law. When adding a Poroelasticity interface in COMSOL Multiphysics® version 5.2a, these two separate physics interfaces and the multiphysics coupling, as a series of nodes, are created. This gives you access to all functionality available in the constituent interfaces. As an example, you can now model poroplasticity by adding a Soil Plasticity node in the Solid Mechanics interface.
Application Library path for an example that uses the new Poroelasticity interface: Subsurface_Flow_Module/Flow_and_Solid_Deformation/multilateral_well
Stress distribution in a poroelastic analysis, from the Application Library's Failure of a Multilateral Well tutorial model.
NOTE: In order to model poroelastic behavior, use the Subsurface Flow Module or a combination of the Structural Mechanics Module and a fluid flow add-on module that supports the Darcy's Law interface.
Stress distribution in a poroelastic analysis, from the Application Library's Failure of a Multilateral Well tutorial model.
NOTE: In order to model poroelastic behavior, use the Subsurface Flow Module or a combination of the Structural Mechanics Module and a fluid flow add-on module that supports the Darcy's Law interface.
Gravity Feature
A Gravity feature is now available for the Darcy's Law, Richards' Equation, and Fracture Flow interfaces. A volume force equal to 
is added on all domains where the fluid flow interface is active and a Gravity feature appears in the model tree.
Two formulations are available to specify Darcy's velocity field under gravity: Acceleration of gravity (default), and Elevation.
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New Flownet Plot
The Richards' Equation interface in 2D and 2D axisymmetric geometries now generates a Flownet 2D plot group by default. This plot combines a streamline plot for Darcy's velocity field and a contour plot for the pressure head variable.
Application Library path for an example that uses the new Flownet plot type: Subsurface_Flow_Module/Solute_Transport/pesticide_transport
The Richards' Equation interface showing the new Flownet plot group. Note the combined contour and streamline plots.
The Richards' Equation interface showing the new Flownet plot group. Note the combined contour and streamline plots.