COMSOL Multiphysics (formerly FEMLAB) is a finite element analysis software package that includes predefined partial differential equations for many fields of physics.
Notes for COMSOL users
COMSOL has a library of the properties of common materials, but if you want to use it, you must start COMSOL in SI units mode. If you try to use the materials library in another units mode, it will use the numerical values of the properties without converting them, and give you wrong answers. For example, the density of concrete is about 2300 kg/m3. If you start COMSOL in FPS (Foot Pound Second) mode, it will use 2300 as the density of concrete in lb/ft3, which is much too high.
Very important fact hidden away in the documentation: "The eigenvalue algorithm does not work reliably when the parameter in the Search for eigenvalues around edit field is equal to an eigenvalue. [If your problem has a zero eigenvalue] you must change the value of this parameter."
See also Software_Tools.
Tutorials
Advanced LIGO ITM
This video tutorial shows how to build a 2D axially symmetric model of an Advanced LIGO fused silica ITM, apply Gaussian heating to one face and solve for the resulting temperature distribution in the test mass.
Video: COMSOL_ITM.mov
COMSOL file: COMSOL_ITM.mph
Eric's COMSOL Extravaganza
COMSOL file: Normal_beam_Heated_Mirror.mph
Tara's cavity sagging
COMSOL file: