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.
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.
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.