COMSOL Multiphysics^® 6.4 Release Highlights

For users of the Porous Media Flow Module, COMSOL Multiphysics^® version 6.4 introduces a new feature to easily enforce periodicity for the flow between two or more boundaries, a new permeability model, and the ability to include a pressure jump across a free–porous boundary. Read more about these updates below.

Periodic Condition

A new Periodic Condition feature has been added to the Darcy's Law and Richards' Equation interfaces to easily enforce periodicity for the flow between two or more boundaries. In addition, it is possible to create a pressure difference between source and destination boundaries, either by specifying the pressure jump directly or by prescribing a mass flow. The model Estimating Permeability from Microscale Porous Structures model showcases this new feature. The periodic condition is typically used to model representative volume elements and compute effective properties for use in homogenized porous media.

Using the new Periodic Condition feature to estimate the permeability of a porous medium consisting of a periodic array of spheres.

Power Law Permeability Model

The Power law permeability model provides a method to estimate permeability as a function of porosity, using a power-law relationship. It is commonly used in reservoir and groundwater simulations to capture the nonlinear dependence between porosity and permeability. The model Estimating Permeability from Microscale Porous Structures model showcases this new feature. As with the Periodic Condition feature, this functionality is typically used to model representative volume elements and compute effective properties.

The Power law permeability model estimates the permeability of a sphere packing as a function of porosity using a Least-Squares Fit function.

Pressure Jump Option for the Free and Porous Media Flow Coupling

The Free and Porous Media Flow Coupling has a new option to include a pressure jump across the free–porous boundary. This makes it possible to model, as examples, the osmotic pressure at a semipermeable membrane supported by a porous spacer material or a pressure jump due to capillary pressure in the case of multiphase flow. The Reverse Osmosis Water Desalination tutorial model demonstrates this new option.

Using the new Include pressure jump across free–porous boundary checkbox for the Free and Porous Media Flow Coupling to model the osmotic pressure at a thin semipermeable membrane in a desalination unit.

New Tutorial Models

COMSOL Multiphysics^® version 6.4 brings the following new tutorial models to the Porous Media Flow Module.

Linear Biphasic Poroelasticity

This example demonstrates how to use the Poroelasticity multiphysics coupling to simulate linear biphasic poroviscoelastic behavior of biological tissues. It models a torsion test and an indentation test on cylindrical plugs of articular cartilage. This model requires the Structural Mechanics Module or MEMS Module and the Nonlinear Structural Materials Module.

Application Library Title:
linear_biphasic_poroelasticity
Download from the Application Gallery

Large-Strain Poroviscoelastic Model of Brain Tissue

This tutorial model shows how to set up a fully coupled poroviscoelastic model of biological tissues. The model is benchmarked by simulating a cyclic uniaxial tension–compression test on human brain tissue. This model requires the Structural Mechanics Module or the MEMS Module.

Application Library Title:
brain_poroviscoelasticity
Download from the Application Gallery

Modeling an LFA Rapid Detection Test

This example models a lateral flow assay (LFA) for the detection of coronavirus antibodies in a 2D geometry, assuming that the chemical species are homogeneously distributed over the membrane thickness.

Application Library Title:
rapid_detection_test_2d
Download from the Application Gallery