Heat Transfer Module

New Functionality in Version 4.2

• Thermal wall functions with turbulence now support the Surface-to-Surface Radiation and Highly Conductive Layer features and their subfeatures.

• New option to define the total power of a domain Heat Source and to define the total Heat Flux on a boundary.

• New Grill Boundary Condition and Vacuum Boundary Condition for setting inlets and outlets properties in fluid-flow models.

• New Fan Boundary Condition on interior boundaries.

• Support for tables to define pressure curves in the Fan Boundary Condition for using fan curves at inlets in fluid-flow models.

• New option to define structures with multiple layers in theThin Thermally Resistive Layer feature.

• New built-in convective cooling coefficients for external natural convection on inclined walls.

• Update and simplification of the variables names and definitions for heat sources and heat flux. A new section about heat fluxes is available in the documentation.

• Incident Intensity boundary condition can be defined using the discrete directions used by the discrete ordinate method.

• Wall boundary condition in Heat Transfer in Participating Media has been renamed to Opaque Surface boundary condition. In version 4.2 it accounts for the thermal contribution of the net radiative heat flux.

• New default plots for Heat Transfer, Heat Transfer in Thin Shells, Surface-to-Surface Radiation, Radiation in Participating Media, Conjugate Heat Transfer, Joule Heating, Inductive Heating, and Microwave Heating interfaces using the new ThermalLight color scale for temperature plots.

Backward Compatibility vs. 4.1

Wall Features in Radiation in Participating Media

The Wall (wall) feature in the Radiation in Participating Media interface has been renamed Opaque Surface (os) in version 4.2. Model Java-files or Model M-files that create and solve COMSOL models containing Wall features need to be updated to use Opaque Surface instead. When the Opaque Surface is used in the Heat Transfer interface in version 4.2, it adds a new heat flux term that is equal to qw, which is the net radiative heat flux. If you do not want to keep this term in an imported model from version 4.1, you must add a Heat Flux feature on the same selection as the Opaque Surface, and the parameter q0 must be set to -id.qw, where id is the physics interface identifier.

Backward Compatibility vs. 3.5a

k-ω Turbulence Model

The k-ω turbulence model physics interface is not yet implemented in version 4.2. It is planned for the CFD Module in version 4.2a.

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 presents an excellent alternative for higher accuracy in models including confined flows.

Turbulent Flow with Wall Functions and Heat Transfer in Conjugate Heat Transfer

Momentum transport Wall Functions are translated into the revised Wall Functions in 4.2. 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.