cartesian vs cylindrical coordinate
Hi My problem is flow through a pipe surrounded by a rectangular block. Now I want to solve 3-D continuity, momentum and energy equations. Now, those equations need to be solved in cylindrical...
View ArticleMatlab function in Comsol handover String
Hi everyone, thanks to the discussion on http://www.comsol.com/community/forums/general/thread/7946/ I've successfully included a matlab-function with 3 arguments (equal to the tree dimensions of my...
View ArticlePiezo energy harvester
Hi, I'm new to this Forum, greetings to all. I am studying on piezoelectric energy harvester, trying to simulate the power output of such an device with COMSOL. I know that there are other discussions...
View ArticleScttering problem using comsol4.2
I wanted to calculate scattering absorption cross section and thereby extinction for a nanoparticle. I am not sure how to go for that in comsol4.2. Can anyone please tell a basic flow to accomplish...
View ArticleCOMSOL 4.3a Installation Problem
After installing 4.3a, whenever I open most files (or try to at least), I get the following error in a pop-up window:
View Articleselection of physics
Hi friends i am trying to build a model for analysis of two gases entering a room and after mixing/diffusion in room the concentration is to find. there should be two inlet conditions for two gases and...
View ArticleTime-dependent solver
Hi, When I simulate my model in a time interval with defined time step, i.e. range(0, 1e-3, 1), the solver automatically drops many nodes and only report solutions for a few time points. How can I...
View ArticleCreating and using external Matlab functions
Does anyone have any experience in creating and using external Matlab functions? I am running Comsol 4.0a, and would like to be able to pass parameters to a Matlab function, do some calculations, pass...
View ArticleWeak Boundary on COMSOL 3.5 a COMSOL 4.2a
Hi, I am chemical engineer of the Mexico City. In the work: square_droplet_2Daxi_reset.mph, that this in the comsol version 3.5a, in the tutorial in the step 7: Open the Equation Systyem > Boundary...
View Article[Solved] Selection Left Click
Hello community, I am faced with a strange problem. I just updated to Comsol 4.3 after using 4.2a for a long time. But it seems I can't left-click on an object to select it anymore. I don't know...
View ArticleUrgent : Boundary layer meshing problem
Hi, I need a help to understand the boundary layer meshing in COMSOL. I have an axisymmetric model of a simple cylinder of diameter radius 6 mm. For the penetration depth of 0.14 mm at the outside...
View ArticleHow to define a dispersive material as a function of COMSOL predefined...
Hi: I defined a dispersive material function (frequency dependent relative permittivity) in Global Definition. Function name: LD_real Expression: ff E-14+0.6 Argument: ff Argument unit: Hz Function...
View ArticleModel saved in 4.2 need to be saved in 4.1
hi friends! i am trying a model of air and hydrogen mixing phenomena. i was using version 4.2 now i am using 4.1. The model i have, is saved in 4.2 i need it to be saved in 4.1 so that i can run it ....
View ArticleParametric Sweep and exporting data
Hi, I'm doing a parametric sweep in a model with a geometry that depends on the same parameter wich I sweep. I run my parametric sweep and works well (the solver remeshes the model for each value of my...
View ArticleBoundary current source vs electric potential source
Hello, I have a question about the AC/DC module -> Electric currents. I made a simple model of a spherical homogenous volume conductor. Inside this sphere I added a cylinder along the 3-axes. On the...
View ArticleHow can I get the field distribution after the incident wave is subtracted?
Hello! I have a question need your help. I calculate a grating model in comsol4.3, and is illuminated at normal incidence with a TM-polarized plane wave. There question is how can I get the...
View ArticleBest way to switch on fields in time-dependent simulations
Hi, Is there a kind of recommendable way of switching on fields in transient emw-simulations. Right now, I'm using the step-function, included in Comsol, and I have some problems with the converge of...
View ArticleNegative port impedance
Hi All, I am currently doing some antenna modeling. The antenna is excited by a 50 Ohm coaxial port. I get reasonable S11 results at resonance but the lumped port impedance is negative e.g. -5 Ohms....
View Article3D Natural Convection Hot Plate
Dear all, I am having trouble with modeling natural convection for a while. I have started with a very simple case of having a hot plate at 150 degC surrounded by room temperature air and want to...
View ArticleBias Current Density
hi!! I need to generate 1.5 Tesla magnetic flux out of a rectangular block. what value of current density (J) should i use? what is the constitutive relation to find the required current density...
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