Microfluidics Module Updates

For users of the Microfluidics Module, COMSOL Multiphysics® version 5.6 brings new averaging options in two-phase flow, simplified setup of initial values of the phases in Phase Field and Level Set interfaces, and new Porous Media features for Transport of Diluted Species. Read more about these features and functionality below.

Easier Setup for Phase Field and Level Set Models

The Level Set and Phase Field interfaces have been restructured: Two Initial Values nodes are now added by default, and the previously used Initial Interface feature has been removed. Instead, the initial interface is automatically placed at the boundaries between the two Initial Values nodes with different initial phases.

The COMSOL Multiphysics version 5.6 UI showing the settings for Initial Values, Fluid 2 and the geometry of a droplet breakup model in the Graphics window. Initial values settings, geometry
The COMSOL Multiphysics version 5.6 UI showing the settings for Initial Values, Fluid 2 and a 3D droplet breakup model, with surroundings reflected in the droplets, in the Graphics window. Initial values settings, 3D model results

Settings for the Initial Values, Fluid 2 feature. Note that the Initial Interface feature is no longer needed. The initial distribution of the level set or phase field function is solved for in the Phase Initialization study step.

New Averaging Options for Fluid Properties Across Phase Interfaces

When the density and/or viscosity ratio in a two-phase flow simulation is large, the use of volume-averaged fluid properties across the phase interface may lead to excessive smearing. Sharpening the transition zone for the fluid properties, or displacing it into one of the two phases, may improve accuracy and/or convergence in some cases. In version 5.6, smoothed Heaviside functions and harmonic volume averages can be used for both density and viscosity. For the viscosity, mass averaging and harmonic mass averaging are also available as options.

A 1D plot with a blue line for volume average, green for Heaviside function, red for harmonic volume average, turquoise for mass average, and magenta for harmonic mass average. Example of averaging Different options for averaging the viscosity across an air–water interface.

Revamped Porous Media Features for Transport of Diluted Species

The Transport of Diluted Species in Porous Media interface is revamped to use the new Porous Medium node. Two new domain features, the Porous Medium and the Unsaturated Porous Medium nodes, are available in the Transport of Diluted Species in Porous Media interface. You can use the new Porous Medium node for assigning material properties to the multiple phases in a porous medium. The new nodes have dedicated containers to define the properties for the liquid, gas, and porous matrix. You can see this functionality demonstrated in the Ceramic Water Filter with Activated Carbon Core tutorial model.

A closeup view of the COMSOL Multiphysics version 5.6 UI with the settings shown for Transport of Diluted Species in Porous Media and a ceramic water filter candle model in the Graphics window. Demonstrating the updated porous media features Contaminant concentration in a ceramic water filter candle.