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Recovering desired eigenfrequencies
Hi, I'm performing an eigenfrequency analysis of a model in the Comsol 4.3a RF module. My problem is that, though I ask for only 1 eigenfrequency, Comsol ALWAYS gives me 2 eigenfrequencies: one purely...
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Error while solving Joule heating: mesh-case 0 there are 665 void equations...
Hi, I tried to simulate joule heating in a copper cylindrical wire with an cylindrical air-void in it. But I am getting following error: Failed to find a solution. Singular matrix. For mesh-case 0...
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Solving a 4th order PDE: how to specify boundary conditions
A fourth order PDE like the biharmonic equation: ∇^4 w = 0 can be placed in Comsol's standard forms by writing u = ∇^2 w, so that we have system of equations: ∇^2 v = w ∇^2 w = 0 where v = v(x,y) and w...
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Failed to evaluate variable: freq
Hi COMSOL Users, I'm new to using the v4.x series of COMSOL, so perhaps I've missed something simple, but I get an error when trying to plot body volume force variables. The error message...
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Heat transfer
hi, i need to calculate thermal conductivity for various volume fraction of ALN with PMMA. In that paper they mentioned about When the sample is given a heat power,the direction of heat transfer is...
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boundary selection problem
Hi When I move the pointer to a certain boundary and click, an adjacent boundary lights up instead of the boundary I pointed at, how do I resolve this? thanks David PS this is a problem that suddenly...
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Test function for Electric field
Hey all I am working in the 2D piezoelectric module and I want to take weak forms of Electric field in different direction, test(pzd.EX) and test(pzd.EY) but its showing error. When I try by making the...
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How I can add data for a solution to a new study?
I'm working on the simulation of an iron foundry, I made a transient thermal study, and I exported data solution in time 200seg temperatures. I would like to know how I can add the output exported to a...
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how to create polar plot in journal bearing
hello, need some help from u all to plot these polar plot. these study about pressure distribution around bearing surface of hydrodynamic journal bearing.. radius bearing : 50mm height bearing : 50mm...
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Two very basic questions about direct solvers
Hi all, I have two very basic questions about direct solvers. 1. Why is there convergence problem with direct solvers? I suppose direct solvers inverse the matrix somehow directly, rather than...
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heat generation calculation
Hi, I am modelling microwave heating by Comsol 4.2 I used heat source domain and electromagnetic power loss density as heat source but I couldn't calculate heat generation terms (W/m^3) When I use...
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Surface tension as a variable
Hello all, I have a general question about surface tension in COMSOL. Can surface tension be assigned as a dependent variable? More importantly, can it vary in time AND space? Or be assigned as a...
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frequency domain study with external circuit
Hi The comsol model gallery includes a frequency domain model of a capacitor. I added an external circuit coupled to the capacitor and a time dependent study runs OK (as shown in a separate gallery...
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Orientation of legends when exporting as .eps
Hello, For some mysterious reason, the legends are turned "upside down" when I try to export a 1D plot as .eps as compared to when I save the exact same picture in any bitmap format. By upside down I...
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How to create a spiral inductor in COMSOL
Hi, I am a new learner of COMSOL. I would like to learn how to create 5 uH spiral inductor. I have researched on website but I could not find the tutorial step by step. I saw only in AC/DC Library with...
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License error: -38
Hello, Whenever I try to run COMSOL 4.3, I get this error : License error: -38 User/host on EXCLUDE list for product User/host on EXCLUDE list for feature Feature: CADIMPORT license path: C;\Program...
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Meshing Air
I'm new to 3D COMSOL and I have the geometry for a chamber that will have air running through it while it performs its function. I am easily able to mesh the geometry, but I'm having problems finding a...
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Multiple MEMS devices in parallel using electrical circuit physics ?
Hello, Here is my model: I am simulating a micro piezoelectric systems. The simulation is complex and can take some time. Then, I use the electrical circuit physics to simulate my systems with an...
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Joule Heating- 3D Rectangular Bar
I have 3D model of a rectangular Copper bar with 3 rods attached to it. These 3 rods provide electric energy to heat the rod. I am not sure what is incorrect with the case set-up, asI have run a very...
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Complex unit i in Comsol
Hi I'd like to simulate a variable containing the complex unit i. I'd like to calculate the voltage V = i*2*pi*f*S*B with i the complex unit.I read the docs and found that i and j are supported as...
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