This is the place where you define the equation as well as the boundary conditions.
I recommend to define the domain by hand rather than using the mouse.Įxample. In the 1D case, this menu contains only a few entries. In the respective Expression field, enter 1e2. They are later available in the physics modeling.Įxample. Constants: Very often, a problem contains a lot of parameters.Axes/Grid Setting: Here you can define the area to be displayed in the graphics window.In the Options menu, you can define some global settings. 1Indeed, multiphysics is one of the main strengths of Comsol Multiphysics! In the Filemenu, you can save your project at any time, and reload it if you want to continue. As a rule of thumb, you have to traverse the main menu (or the button line) from left to right. If you stop with the mouse over a button, a bubble help will appear. Below the main menu, there is a button line providing shortcuts to the most important submenu items. The menu contains the main steps to be taken in obtaining a solution. Its main contents is the a graphics window displaying the domain under construction (of course, it is empty in the beginning). The name of the unknown function will be u while the independent variables are x and t.Īfter you have accepted your choice in the Model Navigator, the main window of Comsol Multiphysics will appear. On the right-hand side of the window, the form of the equation will be displayed. PDE, Coefficient Form -> Time-Dependent Analysis Even if there is a predefined application mode for the heat equation, we will use the coefficient form for demonstration purposes. The Multiphysics button leads to the more advanced features of Comsol Multiphysics.1 If you want to load your own model, press OK without selecting a new application mode.Įxample. I recommend that you do not change the name of the application mode. Here you can select the space dimension of the problem (1, 2, or 3), the application mode, the name of the dependent variable(s) (this may be more than one if you have a system of equations), and the type of the finite element to be used. You will be confronted with the Model Navigator. In order to invoke Comsol Multiphysics, go to a directory of your choice and run the command: If you are using Comsol Multiphysics in other installations, please follow the instructions coming with the installation CD. Under Solaris or Linux, issue the command Here we have d a =1, c =1, f = Q, and all other coefficients are vanishing.Ĭomsol Multiphysics is available on all supported platforms.
As a running example take the one-dimensional heat equation Observe that a dependence on u is not recommended.ġ.) Example. The coefficients of the coefficient form may depend both on x, t, and u. For most nonlinear problems, the general form needs to be used. It can only be used for mildly nonlinear problems.
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