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Solutions - PDEs, ODEs, and other equations

1031: Flux through interior boundaries When plotting the normal flux through the boundaries in my model, I am surprised to see that two adjacent boundary segments have opposed flux. This...
1019: Can I solve systems of nonlinear algebraic equations with COMSOL? Can I solve nonlinear equation systems with COMSOL? Yes, you can. The easiest way is to use the daspk solver from the COMSOL Script command line....
1007: Solving Algebraic and Transcendental Equations How can I solve algebraic equations and transcendental equations in COMSOL? The Global Equation interface can handle more than ODEs. By skipping the...
973: My flux calculation seems wrong I am solving a diffusion-like problem in COMSOL Multiphysics and discovered that boundaries that are defined with insulation/symmetry conditions...
965: 3D Euler Beam coordinate system 3D beams that are modeled on edges of a 3D structure need a local coordinate system for a number of reasons. Indata: You need a coordinate system...
955: Optimization Can I do optimization in a COMSOL Multiphysics model? Optmization Lab If you run COMSOL Multiphysics in combination with the Optimization Lab, it is...
952: Negative concentrations Why do I get negative values of the concentration? There are several possible reasons for negative concentrations: Numerical errors The most common...
945: Imposing both Neumann and Dirichlet condition on a single boundary I would like to solve the equation div(grad u) = 0 in 1D with the following boundary conditions: x = 0: u = 2 AND du/dx = 3 x = 1: no conditions...
942: How do I use coupling variables from the command line? How do I use coupling variables from the command line, for example to make periodic boundary conditions or impose an integral constraint in a script...
939: Can COMSOL Multiphysics handle polar, spherical, and cylindrical... Can COMSOL Multiphysics handle polar, spherical, and cylindrical coordinates? And how can I define these coordinates? You can define your own...
913: Computing Time and Space Integrals How do I compute time integrals in my time-dependent COMSOL Multiphysics model? How can I calculate a space integral? The best way to compute time...
905: Smoothed step transitions in COMSOL Multiphysics When you provide a function, coefficient or material property as a step function to COMSOL Multiphysics, you may experience convergence problems....
895: Can COMSOL Multiphysics handle left-handed materials? Can COMSOL Multiphysics handle left-handed materials? Introduction Left-handed materials/media is an important topic in optics and ...
875: What is meant by degrees of freedom (DOFs) in COMSOL Multiphysics? What is meant by degrees of freedom (DOFs) in COMSOL Multiphysics? The solution time and memory requirements are strongly related to the number of...
852: How can I model nonlinear magnetic materials? How can I model nonlinear magnetic materials? How can I introduce an experimental B-H curve? A nonlinear magnetic material can be implemented either...
816: How do I solve a PDE with space derivatives of order higher than two? How do I solve a PDE with space derivatives of order higher than two? For example, the equation uxxxx + uxxyy + uyyyy = f for a function u(x,y). ...
808: Can I compute the magnetic forces in COMSOL Multiphysics? Can I compute the magnetic forces in COMSOL Multiphysics? Yes, there are three different methods that can be used under different circumstances:...

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Solutions - PDEs, ODEs, and other equations