Formerly FEMLAB, COMSOL is a finite element analysis software package for various engineering and physics applications, with special emphasis on coupled phenomena (multiphysics).

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plot issue in Comsol Multiphysics

I'm dealing with an Axisymmetric 2D model in Comsol Multiphysics. In other words I working in cylindrical coordinate system. Now I need to build a graphic which represents a changing of some variable ...
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COMSOL - 2D box - get for every x an average value over y (line average apply for more lines) [closed]

I would like to ask you for your help. I have 2D box. I know how to do an 2D cut line and compute an average value of someting over this line. (in Results -> Data Sets -> Cut Line 2D and then ...
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Anyone knows why surface-to-ambient radiation is not applicable to interior boundaries in comsol?

I have a 2D model consisting of a square piece of electrical insulator and in the middle I have a thin rectangle acting as a wire. I'm running a current through it so I heat it up to 500 K. Clearly it ...
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Integrating an Ordinary Differential Equation over a domain in Finite Element Methods

I'm trying to get a deeper understanding of the Finite Element Method (FEM) to better understand what I do in COMSOL and FEniCS. The sketch below shows the problem that I want to solve in FEM. The ...
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COMSOL RF or Opitcs Circular Polarization

Anyone know how to model circularly polarized light in COMSOL 4.3? And also validate it! I thought this would be easy, the following being my solution. I'm using a frequency domain solution. I'm ...
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Calculating Divergence in COMSOL

Is it computationally safe and accurate to use the following equation in COMSOL to compute the divergence of the vector quantity J (instead of using its general built-in equations that have $\nabla$ ...
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How can I define Poisson’s equation in general and weak form in comsol

I want to simulate capacitor with Comsol by using Poisson's equation in genaral and weak form. How can I specify boundary condition for this case?
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How to solve global equation in Comsol only once?

Let's assume that I have a comsol model for solving time-dependent problem. In order to find initial value for one variable I need to solve simple algebraic equation before starting simulation, ...
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Basic Finite Element Method (FEM) question: assembly and re-assembly

I'm reading up on the Finite Element Method (in Zienkiewicz's Book) , so I understand better what I'm doing in FEniCS and COMSOL. Currently, I'm wondering about this: Using FEM to solve fluid flow ...
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279 views

Divergence in COMSOL

I'm trying to calculate the divergence of a vector quantity $L(L_x, L_y, L_z)$ in COMSOL. I calculate it using the built-in differentiation operator as follow: $$\nabla L = ...
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Stress due to the mismatch of thermal expansion coefficients of two different attached materials in COMSOL

I'm simulating the thermo-electro-mechanical behavior of a copper wire which is surrounded by silicon dioxide. In other words, the wire segments is under mechanical and thermal loads and at the same ...
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Coupling Equations in COMSOL

I want to solve the following equations: $\frac{{\partial n_D(T)}}{\partial t } = \nabla. (D\nabla n_D(T) -vn_D(T) )=0$ where $D$ is the diffusion constant, $v$ is the velocity and $n_D(T$ is the ...
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Time stepping in comsol multiphysics

I have an important question I wasn't able to find an answer to. i would like to know which is the algorithm comsol uses in order to correct the time step it uses. For example, when you try to solve ...
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601 views

Stationary solution converge but time dependent doesn't

I've coupled a COMSOL model for fluid dynamics with a very simple pde that model the transport of humidity in air. When I solve it for the stationary case, the solution converge easily, but when I ...
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Can I use RANS to see the effect of mixed convection?

my question is: can I use a RANS simulation to see the effect of mixed/natural convection? Actually I have also a second question: I would like to do this in Comsol multiphysics, but it seems that it ...
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177 views

How to include parameters in plot title in comsol?

I have a comsol model. I want to draw a few plots for different values of a global parameter called plot_z, e.g. if plot_z can ...
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702 views

In Comsol Multiphysics, is there a way to change parameter values when something happens in the solution?

I'm beginning to learn Comsol Multiphysics as part of a modelling course in my masters degree. Currently, we are modelling a circuit with a spark gap, which presents some problems for me. I'm using ...
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COMSOL - Implementing Perfectly Matched Layers (3D)

If there are any COMSOL gurus here, I want to simulate a 3D RF system infinite in 1 direction. I realize I need to use PML's, but am unsure how to configure them. it seems that simply scaling them by ...
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COMSOL on Ubuntu (10.04 LTS and 11.04)

I am running into a problem with COMSOL 4.2.0.187 on Ubuntu (both 10.04 LTS and 11.04). When using the option -np x with x > 1, ...