COMSOL 4.2a API Changes

•	Class files compiled with COMSOL Multiphysics version 4.1 or earlier need to be recompiled.

•	The Far Field feature in the Electromagnetic Waves interface has changed from being a boundary feature with a boundary selection only, to a domain feature with a domain selection. It also has a subfeature — a boundary selection.

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The dependent variable associated with gauge fixing in the Magnetic Fields, Magnetic and Electric Fields, Electromagnetic Waves, and Transient Electromagnetic Waves interfaces is now unique to each interface. It is no longer available in the model scope, for example, mod1.psi. Instead, the gauge fixing field is only available in the interface scope, for example, as mod1.mf.psi.

•	In the scattered field formulation in the Electromagnetic Waves interface, the scattered field is no longer available in the model scope (for example, mod1.relEx). Instead, the scattered field is only available in the interface scope as, for example, mod1.emw.relEx.

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In the Solid Mechanics interfaces (SolidMechanics, PiezoelectricDevices, AcousticStructure, Poroelasticity, ThermallyInducedStresses, JouleHeatingThermalExpansion, TransientAcousticStructure, and FluidStructureInteraction), tensors in local coordinate systems (el, eel, Sl, si, and ei) have new names. The coordinates of the local system (for example, x1, x2, and x3) are no longer used. Instead 1, 2, and 3 are used together with double indexing for all components. As an example, elX2 is replaced by el22 and elx2x3 is replaced by el23. The tensors si and ei are now called Sil and eil.

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In the Darcy’s Law interface and the Richards’ Equation interface in the Subsurface Flow Module, fluid compressibility is now a material parameter and no longer has a default value. If the default value was used, you now have to set the value. The following example sets the permeability to the old default value:

model.physics("dl").feature("smm1").set(chif_mat,userdef);

model.physics("dl").feature("smm1").set(kappa,4e-10);

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In the Poroelasticity interface in the Subsurface Flow Module, the fluid compressibility and the Biot-Willis coefficient are now material parameters and no longer have default values. If the default values were used, you now have to set the value. The following example sets the permeability to the old default value:

model.physics("dl").feature("smm1").set(chif_mat,userdef);

model.physics("dl").feature("smm1").set(kappa,4e-10);

•	The Level Set and Phase Field interfaces now include the Initial Interface feature by default. If you have a model that was created in an earlier version of COMSOL Multiphysics, it will fail to create a feature with the same tag name.