Backward Compatibility with Version 4.3

Fluid-Structure Interaction

The Fluid-Structure Interaction (FSI) multiphysics interface has been updated. The separate vWall field is no longer required and has been removed. FSI models from 4.3 and earlier versions that include Time Dependent study steps will be affected in the following ways:

•	Model files for Java® will fail. Any reference to the vWall field must be removed.

•	Models older than 4.3 (that is, 4.2a and older) must clear their time-dependent solutions when opened in 5.2a. An alternative procedure is to:

-	Open the model in version 4.3.

-	Right-click any study with a time-dependent study step and select Update Solution.

-	Save the model.

-	Open the model in version 5.2a.

FSI models with only stationary study steps will not be affected. Note that vWall will still be available as a variable. Hence, references to fsi.vWall made in, for example, another physics interface still work.

Brinkman Equations and Free and Porous Media Flow

The momentum equations in the Brinkman Equations interface and the Free and Porous Media Flow interface have been corrected. The term −Qbr·u/εp2 in the right-hand side previously lacked the factor 1/εp2, where εp is the porosity.

Reacting Flow Interface Name Change

The Reacting Flow interfaces have been renamed Reacting Flow in Porous Media. If you open a model using either the Reacting Flow, Diluted Species or the Reacting Flow, Concentrated Species interface, the interface is renamed Reacting Flow in Porous Media.

Weak Constraints Update for Fluid Flow Interfaces

The weak constraint formulations for the following boundary conditions in the following interfaces have been updated:

Laminar Flow and Creeping Flow

•

Symmetry

•	The Slip boundary condition in the Wall feature

Turbulent Flow, k-ε and Turbulent Flow, k-ω

•

Symmetry

•	The Wall functions boundary condition in the Wall feature

•	The Moving Wall (wall functions) boundary condition in the Wall feature

•	The Slip boundary condition in the Wall feature

Turbulent Flow, low-Re k-ε and Turbulent Flow, Spalart-Allmaras

•

Symmetry

•	The Slip option in the Wall feature

Rotating Machinery

•

Symmetry

•	The Slip boundary condition in the Wall feature

•	The Wall Functions boundary condition in the Wall feature (turbulent flow only)

•	The Moving Wall (wall functions) boundary condition in the Wall feature (turbulent flow only)

•	Rotating Wall (turbulent flow only)

Bubbly Flow

•

Symmetry

•	The Slip boundary condition for the liquid phase in the Wall feature

•	The Wall Functions boundary condition for the liquid phase in the Wall feature (turbulent flow only)

Mixture Model

•

Symmetry

•	The Slip boundary condition for the mixture in the Wall feature

•	The Wall Functions boundary condition for the mixture in the Wall feature (turbulent flow only)

Euler-Euler Model, Laminar Flow

•

Symmetry

•	The Slip boundary condition for either phase in the Wall feature

•	The Slip boundary condition for either phase in the Inlet feature

Brinkman Equations and Free and Porous Media Flow

•

Symmetry

•	The Slip boundary condition in the Wall feature

Two-Phase Flow, Level Set

•

Symmetry

•	The Slip boundary condition in the Wall feature

•	The Wetted Wall boundary condition in the Wall feature

•	The Moving Wetted Wall boundary condition in the Wall feature

•	The Wall Functions boundary condition in the Wall feature (turbulent flow only)

•	The Moving Wall (wall functions) boundary condition in the Wall feature (turbulent flow only)

Two-Phase Flow, Phase Field

•

Symmetry

•	The Slip boundary condition in the Wall feature

•	The Wall function boundary condition in the Wall feature (turbulent flow only)

•	The Moving Wall (wall functions) boundary condition in the Wall feature (turbulent flow only)

Non-Isothermal Flow and Conjugate Heat Transfer

•

Symmetry

•	The Slip boundary condition in the Wall feature

•	The Wall Functions boundary condition in the Wall feature (turbulent flow k-ε and turbulent flow k-ω only)

•	The Moving Wall (wall functions) boundary condition in the Wall feature (turbulent flow k-ε and turbulent flow k-ω only)

High Mach Number Flow

•

Symmetry

•	The Slip boundary condition in the Wall feature

•	The Wall Functions boundary condition in the Wall feature (turbulent flow k-ε only)

•	The Moving Wall (wall functions) boundary condition in the Wall feature (turbulent flow k-ε only)

These boundary conditions are now formulated using the same set of Lagrange multipliers as all of the other boundary conditions for the dependent velocity variables. The previously used Lagrange multiplier un_lm has been removed.

When you open models saved in version 4.3, they include un_lm until the model is re-solved. In some cases, occurrences of un_lm in the solver sequence must be replaced manually. This is the case if un_lm was the only Lagrange multiplier component in a segregated group or the only Lagrange multiplier component of a Vanka smoother. Alternatively, you can generate a new automatic solver sequence. Models saved in versions prior to version 4.3 must either be re-solved in version 5.2a for postprocessing, or opened and re-saved in version 4.3 before being opened in version 5.2a.

Weak constraints for the Interior Wall feature are no longer available.

Revision of the Turbulence Models

The formulations of some variables in the turbulence models have been revised in order to improve accuracy. Models using a turbulence model can display a different convergence behavior in version 5.2a than in version 4.3 and the results can differ slightly between the versions.

Euler-Euler Model, Laminar Flow

The results from models using the Euler-Euler Model, Laminar Flow interface may differ in between versions 4.3 and 5.2a due to the more general formulation for the viscous stress in the momentum equation for the dispersed phase. The behavior in the old formulation may be reproduced by dividing the dispersed phase viscosity, μD, by the variable ee.phidPos.