New Functionality in Version 4.1

  • Permeability and porosity can be obtained from the Material Library in the Darcy’s Law and Brinkman’s Equation interfaces.
  • The variables defined by the Reaction Engineering interface do no longer require scopes. This makes it easier for the user to interpret and edit automatically generated expressions, for instance, describing reaction kinetics.

Backward Compatibility vs. Version 3.5a

Pseudo Application Modes

The Pseudo application modes for species transport in version 3.5a allow for the use of the dependent variable for time as a space coordinate in the direction of the flow.

The corresponding physics interfaces are not yet implemented in version 4.0a. They are planned for a later version

Special Basis Functions or Elements

None of the special basis functions or elements for the finite element formulation of flow problems included in version 3.5a are available in version 4.0. However, bubble elements and streamline diffusion are equivalent. Hence, old model that utilized bubble elements can be solved using streamline diffusion instead.

Other special elements that were available in 3.5a will not be re-implemented in version 4. The reason for this is that the stabilized formulation in version 4.0a gives high accuracy to a relatively small computational cost compared to the special elements.

Thin Boundary Layer Pair Boundary Conditions

The thin boundary layer approximation approximates the mass flux perpendicular to an interface according to:

where ni denotes the flux of species i, n the normal vector, cs the surface concentration, and cb the bulk concentration of species i.

In the case where cs actually is a concentration in a separate domain, so that the interface between two domains requires a discontinuous concentration but a continuous flux, this condition could be defined in 3.5a using pair boundary conditions.

Figure 1-2: Example of two domains with two separate dependent variables for chemical concentration.

Version 3.5a models using this functionality are not automatically converted to version 4.1. However, you can covert these models manually in version 4.1 by using separate fields for the surface and bulk concentrations.

Equilibrium Reactions and Mass Transport

The equilibrium reaction assumptions defined by entering in the Reaction Engineering interface does not automatically generate space-dependent formulations. This functionality will be implemented in a later version.