COMSOL Multiphysics^® 6.4 Release Highlights

For users of the Microfluidics Module, COMSOL Multiphysics^® version 6.4 introduces a predefined formulation of the Marangoni effect driven by concentration gradients, an efficient alternative for modeling rotating domains, and more. Read about these updates below.

Marangoni Effect Driven by Concentration Gradients

For microfluidic devices and processes, the classical example of the concentration-gradient-driven Marangoni effect is now included in the Free Surface and Fluid–Fluid Interface features. This functionality enables the modeling of surface-tension-driven phenomena such as the "tears of wine".

Rotating Frame Feature as an Alternative to Rotating Domains

The new Rotating Frame feature expresses fluid flow equations relative to a stationary or time-dependent rotating frame, providing an inexpensive alternative to rotating domains without having to add equations. It also offers options for using a reduced pressure formulation or including the hydrostatic pressure approximation for the centrifugal force.

A model of a free liquid surface formed by the rotation of the fluid using the new Rotating Frame feature.

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 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.

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.

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.