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showing the error circular variable dependency
I have to solve two coupled equations. They are 1) A ∂T/∂t+k/r*∂/∂r (r*∂T/∂r)+B*T*∂a/∂t=0 , Where A=(rho*c)eff = constant, B=1/s*(1-rho)*c*1000/M=constant , k=constant, with initial condition at t=0,...
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difference between 'fpt.V' and 'fpt.vx'
Hi everyone: I use the fluid particle tracing module(fpt) to calculate the trace. I want to know the differences between the 'fpt.V'(particle belocity magnitude) and the fpt.vx,fpt.vy,fpt.vz(particle...
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Regarding coupling 3 physics
Dear all, I am simulating power cable exposed to natural convection, i.e. in air. I am using Joule Heating Physics which has by default Electric Currents and Heat Transfer in Solids. But when define...
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Best way to query electric field at (x,y,z) coordiantes?
Hello, Some time ago I have set up a method to query the electrostatic field in my 3D model at given (x,y,z) coordinates, using a 'Cut Point 3D' node. From a java code, I repeatedly set the (x,y,z)...
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Free tethedral mesh problem for thin plates
Hi everyone, I want to mesh a thin plate with 0.1 um thickness and 820 x 820 um square. I used free tetrahedral mesh but my process always stop around %20 and doesn't proceed any more. Do you have any...
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Limited cut plane
Hey everyone. I'm currently working on a frame for a undergraduate project. I want to make a limited cut plane to evaluate the stress in the connection between a beam and a frame. This is to help me...
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Simulating a single layered coil wound directly on top of itself.
Hello, We are designing an electromagnet that uses multi-turn coils. The wire making up the coils is to be tape-like and wound directly on top of itself instead of being wound like a solenoid. Is it...
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How to add a complementary error function
Hi, How to add a complementary error function in Comsol. Thanks all Shuai YUAN
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Butler-Volmer kinetics
As an electrochemist I cannot understand the formulation of the equation of the electrode reaction kinetics (attached). Why is there (n - eta) in the first exponent, instead of 1- eta? The formulation...
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livelink pgtag for existing plots
Hi, I want to export my plots from comsol to matlab, to tweak and export them as eps. I am using comsol 4.4. The plots are already made in the comsol model, and I have loaded the model up in matlab....
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how to solve Navier stokes in comsol 4.4
Dear All. Please am trying to solve coupled navier stokes equation with temperature equation in comsol version 4.4 but don't really know how to input the temperature equation along side with the navier...
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Find Forces on Spindt Tip Gate
Hi all, I have modeled a Spindt-type cathode for my lab and would like to evaluate the electrostatic forces acting on the gate of the model. I am having trouble setting up Force Calculation for the...
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Inconsistent units in a hyperelastic material model
Hi, I am trying to create a user defined hyperelastic material model. For the isochoric strain energy density (Wsiso) I defined two different terms, Wf and Wm in the following way: Wf =...
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the problem of reactions and domains
I am learning to use COMSOL and I have a problem. For the 1-d discharge model, we use polygon to divide one domain into multiple domains, but how can I add different reactions to the different domains?
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Launching TE11 mode in 2D axisymmetric
hi, i want to simulate a circular waveguide in 2D axisymmetric and want to launch TE11 mode.so,can any body tell me how to launch this mode.actually i am not getting desired result.
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Electric field norm - what is it?
This may be a stupid question, but I am brand new to COMSOL so please be patient with me. When I'm processing results, say plotting 2D surface plots, COMSOL provides a list of expressions it can...
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time varying current
Hi, im new in COMSOL and would like to know at first: How can i simulate a time dependent electrical current. I guess, at first i have to choose the " Study Type - time dependent". I would like to...
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How to mesh touched thin busbars for magnetic field calculation with AC/DC...
Hi all, I'm calculating the magnetic field distribution of a system, which mainly consists of bus bars as shown in the attachment. (The model is imported into COMSOL via the LiveLink interface.) Since...
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Sources
Hello everyone, could someone explain to me what is the (mathematical) main differences between edge source and source on domains? Thanks in advance, Clément Dupont.
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Parallel plate capacitor 2D vs 3D issue
I'm a beginner COMSOL user. I came across this problem while i'm doing some test simulations. I've simulated a parallel plate capacitor in both 3D and 2D. I wanted to see if I can extract the same...
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