New Functionality in Version 4.1
- Surface-to-surface radiation and radiation in participating media are integrated in the main Heat Transfer interface for easier coupling to other heat transfer mechanisms.
- New Fan Boundary Condition for using fan curves at inlets in fluid-flow models.
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
K-ε Turbulence Model
The new wall functions have the potential to deliver higher accuracy than the formulation used in 3.5a. They might, however, require finer wall resolution. Hence, a 3.5a turbulence model can often benefit from an additional boundary layer mesh or refined boundary layer mesh when imported into 4.1.
K-ω Turbulence Model
The k-ω turbulence model physics interface is not yet implemented in version 4.0a. It is planned for the CFD Module in version 4.2.
Version 4.1 includes automatic translation of models built with the previous k-ω turbulence model. When opened, the full model, including initial values and boundary conditions, is converted to the k-ε turbulence model. Once opened, the model can also be also be changed to the Low-Reynolds k-e Turbulence Model interface. The latter physics interface present an excellent alternative for higher accuracy in models including confined flows.
Turbulent Flow with Wall Functions and Heat Transfer in Conjugate Heat Transfer
Highly conductive layers on the interface between a solid and a fluid are not yet fully implemented and give incorrect results when used in combination with wall functions in turbulent flow. This is caused by the incorrect definition of the wall temperature as the average of the solid and fluid temperature in these physics interfaces.
In some case, you can correct this in equation view. Please contact technical support if you run into problems with such a model.
Momentum transport Wall Functions are translated into the revised Wall Functions in 4.1. The Heat equation Wall Functions are also translated, but the translated formulation uses the default turbulence modeling constants, regardless of the values that were defined in Physics>Scalar Variables in 3.5a.
Surface-to-surface radiation in combination with Turbulent Flow and Heat Transfer
It is currently not possible to include surface-to-surface radiation in models using the k-e Turbulence Model and heat transfer interfaces. The reason for this is that the wall temperature is incorrectly defined as the average of the fluid temperature and the solid temperature in version 4.1. However, it is possible use the Low-Reynolds k-e Turbulence Model and the Spalart-Allmaras turbulence model with surface-to-surface radiation.