Eigenvalue analysis " Mass matrix is zero"
I am trying to run a Static Eigenvalue analysis of a structure . My model is a stone-building , so i just enter the properties of the material and the constraints . When i solve the problem appears the...
View ArticlePoroelastic waves - acoustic module - material definition
Hi, I would like to model a poroelastic material with the acoustic module. However, can you tell me how I can link my parameters to material proporties. My parameters are : - porosity - tortuosity -...
View ArticleNewbie needs help seting up ramp function as voltage source
I am new to comsol and cannot figure out how to assign a rect function as the input source to a strip of copper. I subsequently need to study the thermodynamics (which I have successfully done in...
View ArticleVery strange displacement values for eigenfrequency calculation of...
I am modelling a piezoelectric cantilever beam using the piezoelectric devices module in 4.2a. For certain beams, which have several piezoelectric elements on one beam, I get a very high value for the...
View Articlecapacitance of a parallel plate capacitor
These are the steps for my capacitor simulation 1. set two solid blocks (dimensions (25x1x20) ) 1 distance away from each other. 2. set a solid box (65x43x60) to surround the plates of the capacitor....
View Article3d laminar flow - solver problem: Segregated group 1.
Hi I´m simulating the convection heat transfer in a pipe. The external surface of the pipe receive solar radiation to heat the fluid that is flowing. I start my model with the laminar flow and after I...
View Articleimport a bmp image into COMSOL geometry
Hey, as stated in this webpage: http://www.comsol.com/products/formats/ Comsol can both read and write few types of images. However, when I tried to import a bmp image as my structure for flow...
View ArticleInput/Output Error Eigenvalue Solver
While trying to complete a parametric sweep eigenvalue study, the eigenvalue solver produced an Input/Output Error. Does anyone have suggestions on how to go about troubleshooting this error? -Model...
View ArticleConvergence issues with level-set conservative form
Hello Everyone, I am trying level-set conservative form for droplet generation in flow focusing device. I have tried the following: (a) non-conservative form: it converges well but mass conservation is...
View ArticleConvergence problem of contact mechanics
Hello, Following the earlier discussions on implementing an algebraic equation into a structural mechanics model, I fortunately got away with writing out explicitly an analytical solution. Thanks a lot...
View ArticleDirect influcence over automatic time-stepping?
Hi everyone, I'm wondering if it is possible to have a model influence the time-stepping algorithm directly? I know that certain things will cause time-stepping issues and I would like to 'inform' the...
View ArticleGeometry optimization
Hello everyone, I´m modeling a simple heat transfer - structural problem, wher I have a 2-D rectangle with a hole in the midle. First I apply a Temperature load that produces expansion in the...
View ArticleCluster computing got stuck :external progress scheduling
Hi,Ihave recently setup a cluster and i had comsol 4.3 on the head node,and i had the installation forder shared, model working directory shared. However,when I am trying to submit a batch job,using...
View Articlewhen to use parameters, variables, and functions
Hi All, Considering global values for now. It seems clear to me when to use parameters - any value that is independent of the independent or dependent variables. But when is it appropriate to use...
View ArticleThermoelectric Effect - Adding the physics
Hello, I'm working in a project on thermoelectric generator. As 'Thermoelectric' physics interface,is not in the physics area/physics list, I was trying to add the physics using the steps given in the...
View Articleparametric sweep
How to add parameters for the circle centre coordinates, and update parametric sweep settings , for change the distance between the two coils -- kishore Naik Mude
View Articlecom.comsol.nativejni.FlNativeException: Incorrect size of returned vector
Dear all, I'm working on a 2D PDE in coefficient form. In my model, one of the coefficients is set up by an external matlab function fun(t,x,y) according to:...
View ArticleTemperature and time-controlled heat generation
hello, I have a model in which (thermally induced) to start a reaction that takes place when reaching a specified temperature heat generation to another. has the heat generation is always a period of 2...
View ArticleWhich new feature(s) du you prefer in 4.3a ?
Hello I wanted to say to everyone: take a look at the Help: Mathematical "functions" and to "operators" there we have now got many newcomers given new flexibility to the GUI analysis, both for...
View ArticleAssing a sinusoidal body force F(x,y,z,t) in comsol 4.3
Dear all, I am trying to simulate shear wave propagation in tissue using a PDE wave equation (I manually defined the equations). In my geometry, I have a 3D box (imaging it is tissue) and in the center...
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