Porous Media Flow Module Updates

For users of the Porous Media Flow Module, COMSOL Multiphysics® version 6.1 provides a new physics interface for multiphase flow in porous media, the ability to define expressions for phase transitions, and enhanced capabilities for the modeling of flow in fractures. The use of the new multiphase flow interface and the phase transition functionality is exemplified in two new tutorial models. Read more about these updates below.

New Level Set in Porous Media Interface

The new Level Set in Porous Media interface includes a Porous Medium feature that can link to the definition of porosity given in the Porous Material node. This feature is also available in the Level Set interface and in the Brinkman Equations, Two-Phase Flow, Level Set multiphysics interface. View these features in the new Resin Transfer Molding of a Wind Turbine Blade tutorial model.

The COMSOL Multiphysics UI showing the Model Builder with the Level Set Model subnode selected, the corresponding Settings window, and the Graphics window showing the wind turbine blade model.
The new Porous Medium feature for the Level Set in Porous Media interface.

User-Defined Phase Transition

In the Heat Transfer in Porous Media interface, the Phase Change Material subnode now includes an option to introduce user-defined phase transition functions. This option enables you to use accurate phase change descriptions from measured data. You can view this feature in the new Phase Change in a Semi-Infinite Soil Column - Lunardini Solution and the existing Frozen Inclusion tutorial models.

The COMSOL Multiphysics UI showing the Model Builder window with the Phase Change Material subnode selected, the corresponding settings, a Function Plot window, and a Plot 1 window showing the Frozen Inclusion model.
Settings for the Phase Change feature to use a user-defined phase transition function for modeling the melting of a frozen inclusion.

Improved Handling of Fractures

In the Darcy’s Law and Fracture Flow interfaces, fractures are now defined using phase-specific properties with the Fracture node. This feature contains a Fluid subnode that describes fluid, such as gas, liquid, or ideal gas, and a Fracture Material subnode that accounts for the fracture properties, such as porosity or transmissivity. Under the Fracture settings, you can describe the flow as Darcian (slow) or non-Darcian (fast), and a new Linearized storage model option is available. In the Darcy's Law interface, you can select whether fractures are highly conductive, such as open channels, or if they can be represented by thin barriers.

The Fracture node has also been added to the Transport of Diluted Species in Fractures and Transport of Diluted Species in Porous Media interfaces and is consistent with other fracture nodes for porous media transport. You can view these improvements in the existing Ceramic Water Filter with Activated Carbon Core tutorial model.

The COMSOL Multiphysics UI showing the Model Builder window with the Fracture node selected, the corresponding Settings window, and the Graphics window with the ceramic water filter model.
The newly designed Fracture feature in the Darcy’s Law and Transport of Diluted Species in Porous Media interfaces. The Settings window shows the new options for the feature in the Darcy's Law interface.

Thin Barrier Multiphysics Coupling

The Multiphase Flow in Porous Media interface contains a new Thin Barrier multiphysics coupling. This feature is optional and makes it possible to add a thin layer that acts as resistance for flow fields of all phases, without having to mesh the layer's thickness.

The COMSOL Multiphysics UI showing the Model Builder window with the Thin Barrier coupling selected, the corresponding Settings window, and the Graphics window showing the thin barrier in a porous medium.
The new Thin Barrier multiphysics coupling for multiphase flow in porous media.

New Predefined Plots

It is now possible to add plots predefined by the physics interfaces after a study has been computed. The new Add Predefined Plots window, which can be opened from the toolbar in the Results section, enables you to select from a number of predefined plots. The available plots are organized in a tree structure where you can select the plot that you want to add by using the Add Plot button.

The COMSOL Multiphysics UI showing the Model Builder window with the Pressure Along Fracture plot selected, the water filter model in the Graphics window, and the Add Predefined Plot window.
New predefined plots for pressure and velocity for the Ceramic Water Filter model.

Climate Data: ASHRAE 2021

Ambient properties, such as temperature, humidity, precipitation, and solar radiation, can be defined from an Ambient Properties node under Definitions > Shared Properties. Along with the possibility of adding user-defined meteorological data, ambient variables can be computed from monthly and hourly averaged measurements from values in handbooks provided by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). The meteorological data from the ASHRAE 2021 handbook has been integrated into COMSOL Multiphysics® and contains ambient data from more than 8500 weather stations around the world. You can view this addition in the existing Condensation Risk in a Wood-Frame Wall tutorial model.

The COMSOL Multiphysics UI showing the Model Builder window with the Ambient Properties node selected, the corresponding Settings window showing the ASHRAE data options, and the wood-frame wall model in the Graphics window.
The weather data from ASHRAE 2021 is used to define heat and moisture fluxes on external boundaries in the Condensation Risk in a Wood-Frame Wall model.

Additional Features for Moisture Transport in Hygroscopic Porous Media

To simplify model definitions, the Moisture Flow multiphysics coupling has been updated so that the evaporation rate variable computed by the Moisture Transport interface is accounted for in the mass balance computed by the Brinkman Equations interface. In addition, the Open Boundary and Inflow boundary conditions can now be applied to exterior boundaries adjacent to domains where the Hygroscopic Porous Medium is active.

New Tutorial Models

COMSOL Multiphysics® version 6.1 brings two new tutorial models to the Porous Media Flow Module.

Phase Change in a Semi-Infinite Soil Column - Lunardini Solution

A line graph showing temperature over one day, marked in blue; two days, marked in green; and three days, marked in red.
Temperature profiles after one, two, and three days for the computed (lines) and analytical (asterisks) solution.

Application Library Title:

phase_change_lunardini

Download from the Application Gallery

Resin Transfer Molding of a Wind Turbine Blade

A wind turbine blade model, most of which is colored in blue and green, with three yellow circles that have red in the middle.
The Two-Phase Flow, Level Set, Brinkman Equations interface is used for modeling the resin transfer molding process of a wind turbine blade. The results show the velocity field and resin volume fraction after 30 minutes of resin injection.

Application Library Title:

rtm_of_a_windturbine_blade

Download from the Application Gallery