Backward Compatibility with Version 5.0

Obsolete features

A number of features are now obsolete because they have been merged or replaced by a more general features. However, when models from COMSOL 5.0 or before contain these features, some of the obsolete features are visible in version 5.2a with a warning sign notifying that the feature is now obsolete (see Table 1-1). Some features have been completely removed (see Table 1-2). A model containing any of them can be opened in 5.2a, but the feature will be missing.

Updating the models is recommended. Use the new feature and remove the obsolete feature to make sure that the model will remain compatible with future versions of COMSOL Multiphysics.

The table below summarizes the changes:

Table 1-1: Obsolete features that are obsolete but than can be loaded in 5.1

Obsolete feature	replace in 5.2a by
Convective Heat Flux	Heat Flux with the Convective heat flux option selected
Surface-to-Ambient Radiation	Diffuse Surface with Include surface-to-surface radiation deselected
Surface-to-Surface Radiation	Diffuse Surface with Include surface-to-surface radiation selected
Highly Conductive Layer	Thin Layer with Layer type set to Conductive
Thin Thermally Resistive Layer	Thin Layer with Layer type set to Resistive

Table 1-2: Obsolete Features that are no longer available

Obsolete feature	replace in 5.2a by
Infinite Element	Infinite Element is no longer defined in the physic interface. Infinite elements are defined in the Definitions section instead.
Electrochemical Heat flux	Boundary Heat Source
Reaction Heat Flux	Boundary Heat Source
Heat Transfer in Participating Media	Heat Transfer in Solids contributing to Radiation in Participating Media
Porous Matrix	Heat Transfer in Porous Media

Note that it is not possible to add any of the obsolete features from the COMSOL Desktop in version 5.2a. Only the new features are available.

Obsolete Postprocessing Variables Deleted in 5.1

List of deleted postprocessing variables: ndflux_acc, ndflux_acc_u, ndflux_acc_d, ntflux_acc, ntflux_acc_u, ntflux_acc_d, nteflux_acc, nteflux_acc_u, nteflux_acc_d, qout, qout_u, qout_d, qin, qin_u, qin_d, qw, qw_u, and qw_d.

Changes in Variable Names

The variable ht.Tvar, used for nonisothermal flow wall functions, becomes a fully scoped variable in the following features:

•	Heat Flux (ht.hf1.Tvar), Line Heat flux, Point Heat flux, and Out of plane heat flux.

•	Heat Source (ht.hs1.Tvar), Boundary heat source, Line heat source, and Point heat source.

•	Diffuse Surface (ht.ds1.Tvar).

The fully scoped variables Ptot, Pbtot, Pltot, and Pstot become P0, Pb, Pl, and Ps, respectively, in the following features:

•

Heat Flux

•	Inflow Heat Flux

•	Line Heat Flux

•	Heat Source

•	Boundary Heat Source

•	Line Heat Source

•	Line Heat Source (Thin Rod subfeature)

•	Line Heat Source on Axis

•	Layer Heat Source (Thin Layer subfeature)

In the Thermal Contact feature:

•	Qfric, QfricPow, and Qrate become Qb, Pb, and Qbpart, respectively

•	Qfric0, Qrate0, Econtact0, hrad0, hgap0, and hconstr0 are removed and migrated to existing variables Qb, Qbpart, Econtact, hrad, hgap, and hconstr, respectively, in old models.

The Change Effective Thickness feature from the Heat Transfer in Thin Shells interface merges htsh.de into the existing variable htsh.ds.

The Heat Transfer in Thin Shells interface also merges the property de and variable htsh.de into existing property ds and variable htsh.ds. An API command such as model.physics("htsh").prop("de").set("de", [...]) now does not have any effect.