Difficulty in using iterative method for Rf problems which has multiple ports...
Hi everybody, have anybody encountered the problem of keep on having ill conditioned preconditioner when you apply a lot of port condition on a single boundary (For grating structure simulations where...
View ArticleSolving For Total Field with Incoming Plane Wave
I am trying to find the total field for the a substrate with an incident plane wave (i.e. sunlight on a substrate). So far I have made an injection port with a plane wave, but the problem is that I get...
View ArticleNo convergence. Relative timestep too small. Double dogleg solver.
Hello, I am trying to use Double Dogleg Solver for a Navier-Stokes problem, and even tough the residuals in the convergence plot have reach 100% for the velocity and pressure segregated step, I get 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 Articlesurface integration (doing calculations with derived values)
Hello, I have a simulation with several subdomains. In the postprocessing, I'd like to relate two of those subdomains, i.e. I want to compare the power flow of say domain 1 to the power flow of domain...
View ArticleCOMSOL Releases COMSOL Multiphysics version 4.3a
We at COMSOL are proud to introduce version 4.3a of COMSOL Multiphysics to the COMSOL community See: http://www.comsol.com/products/4.3a/ This introduces: * LiveLink™ for Excel® * LiveLink™ for Solid...
View ArticleEstimated error in the energy norm OR the error norm.
Hello everyone, I am having trouble with something that I can't seem to find any help about in COMSOL support. I only see it mentioned very little and not in very much detail in the help documents. I...
View ArticleHow do you know which resonant frequency of the cantilever is the proper one?
Hi, everyone. I'm quite confused. It's a rectangular beam,with one end fixed. Then I do the eigenfrequency study. When I apply different mesh method to the beam, for example, first I use Free...
View ArticleMagnetic Fields, No Current
Hi everyone, So I've been trying for a while now to bypass the problem of creating an external magnetic field in *other* AC/DC modules; but now I see that in the MFNC there are two options: External...
View ArticleSphere-Sphere Forces
Hello. Firstly, greetings to everyone, I am new here. So, I am trying to build a model based on this article:...
View ArticleEigenvalue 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 ArticleTemperature Depdendent Electrical Conductivity acting weird.
Hi Everyone, I have two simple questions that I have been unable to answer after trying to work on them for a week. Please help me: 1) I have a very simple model (which I have attached), I am passing a...
View Articledifferent results of simulating mechanical resonant frequency
I am trying to simulate the longitudinal (x axis) mechanical resonant frequency of a free standing beam. I set the constrain at y and z axis and did the simulation. However, even I keep every...
View Articlepid control and constraining a variable
Hi, i'm making a pid control of a heat exchanger and I need to constraining the inlet velocity of fluid. The inlet velocity is calculated by the pid control law, but need to be constrained between...
View Articleerror: The object 'Type: Save Point Geometry Tag: geom1' is not contained in...
Hi all- I have been working on a model for some time, and just trying to optimize the solver settings. I saved the model today, and then opened it up again to work on it, and now get this error for any...
View Articleconstraining 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 Article