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Initial condition for time dependent study

Hi, I'm trying to model free vibration of a small PZT cantilever (MEMS). I need to apply some initial conditions on displacement in a time dependent study. How can i do it? Thanks Andrea

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Using external file data for heat source

Hi all, I am trying to solve a model for heat transfer in solids using external data as heat source input. The geometric model is simple and composed of 3 separated bodies attached together by a...

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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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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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flow boundary conditions: periodic velocity fall and normal velocity zero

Hello, I am attempting to simulate a 2D flow of a suspension of solid disks on a square lattice. To reduce the computational expense of this simulation, I'd like to consider shear on a single disk at...

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time dependent coupled thermal structural with slow & fast pressure & thermal...

I ran a time dependent coupled thermal-structural problem with temperature dependent structural and thermal properties. When the thermal and pressure pulses were ramped up over two seconds no problem....

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Current Source and violation of Maxwell-Ampère’s law

Hi, I have setup a model using both Electric Currents and distributed ODE and PDE interfaces using a simple 2D square geometry. One boundary of the geometry is set as ground and another used to apply...

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heat transfer module

hi, I am new for COMSOL multiphysics.. i was modeled a breast with its properties can we apply heat to the tissue for certain period of time?can you help me how to do it?

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Question about using multiple processors in Gui mode for "form union" operation

Hi, I am currently working in the RF module on a cluster. Right now, I'm working with a very large geometry (large in that it contains many domains). It is so large that it takes a very long time for...

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Calculating advective/diffusive fluid flux over a boundary -darcy's law and...

Hello, Currently, I am modeling the transport of diluted species under concentration gradient and pressure differential in the soil which enters the building through foundation cracks. I am using two...

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RF module, why cannot I get expected beam of light

Hi I am trying to get a beam of light. I tried the expression “Ex=exp(-(x^2+y^2)/w0^2)*exp(-j*emw.k0*z)” when solving for scattered field instead of full field. I right clicked “solver...

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Compatibilty

I am using COMSOL 4.1 RF Module. When I try to open a file older than version 3.5 I got error message. Is there a way to open those files? I think I should be able to open them since the later versions...

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Transmission spectrum for optical waveguide

Hello, I am currently trying to extract a transmission spectrum from a Si waveguide on top of SiO2 substrate. There are some gold particles on top of the Si (this configuration is taken from an article...

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How to set different thermal conductivity in different direction?

I am trying to simulate a heat transfer model which includes layers with different thermal conductivity in X-Y direction and Z direction. Is it possible to assign a user defined material and have...

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sinusoidal function

Dear all I have to use a sinusoidal function [e,g X0+(X1*(cos*(w*t)))]. Where and how can I write it? rgds Anup

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Negative port impedance

Hi All, I am currently doing some antenna modeling. The antenna is excited by a 50 Ohm coaxial port. I get reasonable S11 results at resonance but the lumped port impedance is negative e.g. -5 Ohms....

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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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Personalized heat source

Good morning everybody, I am a novice in use of COMSOL, I want to simulate the propagation of heat through a material, sounds easy but my heat source is a surface defined by a matrix (every pixel is a...

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export animation

I try to export an animation to file. Comsol 4.3a displays the animation and takes time for the writing process but the file is not actually written. What could I do wrong?

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Time dependent study convergence

Hi, I am trying to model laminar fluid flow, heat transfer in fluids, and mass diffusion simultaneously in comsol using transient solver. The problem is that when I put the upper limit for time 1...

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