constraining a boundary condition
Hi, Anyone know how I can input a constraint in a boundary condition? I have a time variant condition (inlet flow), but I want to constraining this value. best regards, Gustavo
View Articlehow to obtain the local value
Hi, I am new to COMSOl modeling and was helplessly stuck by a problem. Here is it: I am trying to model the fluid flow in a porous tube, which can not be wetted by the fluid. There is relative vacuum...
View ArticleNACA 0012 Airfoil with Spalart-Allmaras turbulence model
Hello, I am new to COMSOL and I thought I would start with a relatively simple model: a NACA 0012 airfoil at 0 angle of attack. The domain is small and the mesh resolution is relatively coarse to get...
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 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 ArticleShape not in interpolation curve not preserved
I'm using an interpolation curve as a way to import a 2D geometry into my model. Figure1 shows the shape of the data I wish to import (as shown in Excel). However when I import this data, saved as a...
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 Articledifference in simulated stress and strain
Hi, I simulated stress for a 2D Silicon structure using "thermal stress" in COMSOL, the simulated stress values are quite consistent with my experimental results. however, when I look at the simulation...
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 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...
View ArticleConductivity of the antenna, RF module
Dear All, I have question concerning optical antennas. I have model which consist of the optical antenna on substrate, and I want to calculate scattering cross section and field enhancement. My...
View ArticleDomain Point Probe Inconsistency
Hi All, Like many newcomers to COMSOL, I'm having trouble with the Results section. As per suggestions on some other posts I've found, I have been using domain point probes to visualize a variable...
View ArticleOscillations
Hi All, I had a quick question, I'm seeing oscillations emerge in my model (a 1D mass flow situation), and I was wondering: is it possible for these oscillations to emerge due to the solver (too coarse...
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