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Finding a mapping of Current Density (variable J) using the Electrostatics...

Hi everyone, I'm making a model using the Electrostatics Interface from within the limited AC/DC Module included with the base COMSOL Multiphysics package. Initially, I tried making my model using the...

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Magnetic field

Hello I created a simple model where the magnetic field and electric wire. 1 Why not spread outside the magnetic induction coil? 2 Why is not moving conductor in a magnetic field? What I made a...

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computing accurate fluxes with periodic boundary conditions?

Hi everybody, does anyone know if I can compute the fluxes accurately, as described in the user guide on page 308 ff. and file 0973 from the knowdledge database etc, when using periodic boundary...

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Electrostatics vs Electric Currents Interfaces. Something is wrong...

Hi everyone, I mentioned this in an earlier post. I believe I have an inconsistency with the software (COMSOL Multiphysics Base Package). This may or may not be intended. When picking between the...

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Invalid Property Value "Lengthunit is a string" Error Message using Livelink...

I have this strange error message when I click on my geometry stating Invalid Property Value - Property: Lengthunit 'length unit' is a string which I cannot get rid of. I think I do not have any length...

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renew COMSOL license using a passcode

I downloaded the COMSOL 4.3a compact DVD image, double clicked it, then a "COMSOL 4.3a INSTALLER" interface showed. When I clicked the "Change license" button, a window pop out that says "specify an...

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Non - Isotherma pipe flow

I am not able to find the "Non - Isothermal Pipe flow" module in my COMSOL 4.3a version. Can you help me out how to find it?? If not, I request you to help me with any method for simulating a pipe flow...

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3D Poisson equation problem coupled with Nernst-Planck equation

I used coupled Electrostatics physics and Transport of Diluted Species physics to simulate this problem. The source term in Poisson equation is the difference between cations and anions. Usually, the...

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Subsonic Ramjet Model

I am attempting to optimize the design of a ramjet to be created for rocket experimentation. I have been working on the model for the fall semester attempting to refine it. I am now using a 2d axis...

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Low Reynolds Turbulent Flow

Hi folks, does anyone know what the "spf.wall_spf" variable means in the AKN Low Reynolds k-ep model. I can see it in the equation view, but other than that, there is no more info... I am really trying...

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bubbly flow: udrift in laminar flow...

Hi, I am currently working with the bubbly flow application mode in a laminar flow. The gaz velocity, ug, is computed thanks: ug=ug+uslip+udrift In the help, is it said that the drift velocity is...

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Two interdependent studies - but I cannot use results from frequency domain...

Dear all, How can I use the result from a parametric (parameter 'b') sweep-frequency domain study (e.g. emw.Ez(b) ) in another function defined under Definitions (e.g. f(emw.Ez(b)) ) which is used as...

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Assigning Materials

While assigning materials to some solids in my model, I am getting a red cross below the material name in Model Builder. What does that mean? What changes should I do to use those materials for the...

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Simulationtime for mapped meshes in 2D and 3D

Hi, Normally I used triangular meshes to simulate thin films on cantilever beams. Because of the very high aspect ratios I 've tried to use a mapped mesh for the rectangular geometry. The amount of...

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Manipulating data from tables

Hi all, I'm working on a model using piezodevice physics in the frequency domain, and I'm trying to plot admittance in dB (rather than siemen). I've found the admittance by taking the surface integral...

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ALE question

Hi, I'm interested in the transient effects of a moving charged object on a grounded one (see image). I have first modelled this using a parametric sweep on the object's x position. But of course, this...

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Generalized alpha time dependent solver

Hi, if I switch from BDF to the generalized alpha time dependent solver the solver works with a timestep of 0 or near zero. I can set a manual time step and the solver calculates the time correctly,...

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Straw Poll: Who would like to see the model gallery documentation overhauled???

Hello all, I thought I'd post this here to get the community opinions before suggesting it to support. If I want to learn how to use an aspect of Comsol I work through example models and I visit the...

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Using step function in kinetic reaction simulation

Hi I am trying to simulate the kinetic reaction of biomolecule interaction in fludic channel expecting to have association and dissociation phase (concentration of complex versus time) in the same...

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Save the Date - COMSOL Conference 2013 Boston, Oct 9-11

Hello, We are excited to announce that the COMSOL Conference 2013 Boston will be held on October 9-11th. With over 50 events to choose from, including training and presentations, this is the premier...

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