New Functionality in Version 4.3a

Moving Frame Support

A new option, activated by default, is available when moving mesh is detected.

When it is active, the heat transfer features automatically account for deformation effects on heat transfer properties. In particular the effects for volume changes on the density are considered. Rotation effects on thermal conductivity of an anisotropic material and, more generally, deformation effects on arbitrary thermal conductivity are also covered.

Improved Pseudo Time Stepping

The pseudo time-stepping algorithm, used per default for turbulence models and for Non-Isothermal Flow and Conjugate Heat Transfer models, has been improved. The new implementation uses a PID regulator, which compared to the 4.3 implementation makes the convergence more robust without using additional iterations. The additional robustness reduces the need for manual tuning of the solvers.

As a result of this update, some old models may experience different convergence behavior compared to version 4.3.

Support for Load Cases

Loads and constraints can act conditionally in models using load groups and constraint groups, which you can include in load cases using various combinations of the defined groups.

Use load groups for heat sources and heat fluxes. The heat sources and heat fluxes can be scaled in the load cases using a scalar weight.

Use constraint groups for temperature conditions.

Load groups and constraint groups are available in the Heat Transfer in Solids, Heat Transfer in Fluids, Heat Transfer in Porous Media, Bioheat Transfer, Heat Transfer in Thin Shells, Conjugate Heat Transfer, Non-isothermal Flow, and Rarefied Flow physics.

Accurate Enthalpy Calculation

A new integration operator is used to compute the enthalpy. This operator is faster and more accurate compared to the previous implementation. Accuracy gains are observed when the heat capacity is temperature dependent or when the density is pressure dependent.

The following variables benefit from this improvement:

  • Internal energy
  • Enthalpy
  • Sensible enthalpy
  • Convective heat flux
  • Total energy flux
  • Total heat flux

Moist Air

The Heat Transfer in Fluids feature now contains a new fluid type, Moist air. This fluid type provides thermodynamics properties of unsaturated humid air. It also provides dedicated postprocessing variables. In particular it is possible to verify if the saturation level has been reached during the simulation. This is useful to avoid water formation to prevent corrosion for example.

This new fluid type replaces the previously existing humid air material from the Liquids and Gases material library.

Improved Default Settings

The Conjugate Heat Transfer physics now contains a Heat Transfer in Solid and a Fluid feature. By default Heat Transfer in Solid is active in all domains and a Fluid has an editable empty selection.

In models containing surface to surface radiation, solid domains are considered as opaque: an Opaque subfeature (with a editable selection set to All domains) is now added by default under Heat Transfer in Solid and Biological Tissue features. Fluid domains are transparent by default.

The total heat flux is now defined as the default expression for vector plots.

Model Inputs Support

Model inputs support is now available in all heat transfer features. It has been added to the Thin Thermally Resistive Layer and Pair Thin Thermally Resistive Layer features.

New Models in Version 4.3a

  • Heating Circuit: this model includes DC-induced Joule heating, heat transfer, and structural mechanics analysis of the thin resistive layer covered on a solid glass plate.
  • Buoyancy Flow in Water: this tutorial provides tools and explanations for successful modeling of natural convection flows.
  • Composite Thermal Barrier: this model demonstrates the use of thin thermally resistive layer boundary condition to model efficiently very thin resistive structure.
  • Phase change: this example demonstrates how to model a phase change and predict the impact of the latent heat on energy transport.
  • Vacuum flask: this model treats the natural convection cooling using two approaches. The first approach is to use heat transfer coefficients to describe the thermal dissipation. The second approach is to model the convective flow of air outside the flask.

Backward Compatibility vs. 4.3

The Default Model List has been Removed

Heat transfer interfaces no longer have a default model list. This list box was used to change the default feature of models. A similar result can be obtained by adding the corresponding domain feature immediately below the default feature and by setting the domain selection to All domains.

Any user Model Java-files that modify the default model value will require a manual update.

Improved Stabilization of Heat Transfer in Solids

The streamline diffusion stabilization for Heat Transfer in Solids and Biological Tissue features has been improved to account for the contributions from linear source terms from Heat Source, Out-of-Plane Convective Cooling, Out-of-Plane Radiation, and Out-of-Plane Heat Flux features. This improves the robustness of the convergence of the models when these contributions are large. This change can modify the convergence behavior of existing models.

Frame Selection in Discretization Section

The Frame type list that was previously available when moving mesh was detected has been removed. The frame type is now controlled by the features, see Moving Frame support for details.

Update of Features Variable Names

In order to avoid name conflicts between features variable names some of them have been renamed.

This change concerns contributive features. Since they are contributing, it is possible to have to similar features active on the same boundary. In order to make it possible to distinguish the variables from each feature, the feature scope has been introduced in the variable name. When the feature tag was appended at the end of the variable name, the variable name uses now a prefix. These changes affect following features variables:

  • Heat Flux
  • Out of plane heat flux
  • Convective cooling
  • Out of plane convective cooling
  • Boundary heat source
  • Heat Source
  • Line heat source
  • Point heat source
  • Edge/Point Heat flux
  • Electrochemical reaction heat flux
  • Reaction heat flux

For example, in Boundary Heat Source feature: ht.surf has been renamed ht.bhs1.surf (assuming that ht is the physics interface tag).

Another example, in the Heat Flux feature, the variable that was previously named ht.q0_hf1 is now ht.hf1.q0.

Any user Model Java-files that use the old variable names in expressions (such as expressions to plot or evaluate expressions including these variables) will require a manual update.

New Default Fluid Features and Opaque Subfeature

In relation to the improved default settings, all Model MPH-files will be automatically converted to be identical to the 4.3 version.

Due to theses new default features, user Model Java-files can be simplified. In addition, in the user Model Java-files that adds the Fluid feature or the Opaque subfeature with the default tag, a manual update is required to avoid a duplicate tags conflict.

Weak Constraints Update for Fluid Flow Interfaces

The weak constraints formulation for the following boundary conditions in the following interfaces has been updated:

  • Laminar Flow
  • Turbulent Flow, κ-ε
  • Turbulent Flow, low-Re κ-ε
  • Non-Isothermal Flow
  • Conjugate Heat Transfer

See the CFD Module Release Notes for details.

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 4.3a compared to version 4.3 and, the result can differ slightly between the versions.