Lumped port
Hi, Do i have to use some particular dimension when i use a lumped port? I mean do i have to use a particular hport an wport ratio? Thanks Nicola
View ArticleDependence of Electric field on mesh size in RF modeling
We would like to model our laser in an RF module, solving for electrical field strength, to see the optical field distribution as a function of layer thicknesses, however we kept seeing unexplainable...
View ArticlePlotting in air, postprocessing, 4.2a, RF module
Dear All, I have some issue. I made some calculation of gold nanosphere on substrate, and now I want to plot normalized electric field. BUt, thing is I want to plot emw.norm^2 not just on sphere, also...
View Articlemeshing a cylinder
Hi All, I have been having some issues meshing a cylinder. When you define a cylinder in COMSOL, it splits the curved face into 4 quarters, and as a result, when I went to mesh the cylinder I was...
View ArticleStop condition
Hi all I am running a time-depedent heat transfer simulation. I want to stop the simulation when the average temperature is higher than 310K. i defined Tm as the average temperature in the domain. I...
View Articlecartesian 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 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 Articleextracting FE matrix equation system
Hi people! I have small issue and I cannot figure out how to solve it. I need your help. I need to extract my stiffness tensor from the FE matrix system into matlab. I know that there is the function...
View ArticleComsol 4.2a, RF MODULE, Mie Scattering
Hello Fellows, Can anyone send me .pdf file about Mie Scattering module, or .mph file but for 4.2a version.? I have to learn about scattering and absorption cross section, so i think it can be very...
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 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 ArticleAssemble and extract matrices for non steady problem
Hello everybody, I'm running Comsol directly from Matlab, and I wish to extract (among the others) the mass matrix for a fluid flow problem. I do know how to extract matrices with the mphmatrix...
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...
View Article