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Accurate inflow/outflow calculation
Hi, I'm using the Free&Porous workflow, but the question is also applicable to Navier-Stokes. I have an inlet and use NormalVelocity boundary condition which, it seems sets up a Lagrange multiplier...
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Modelling of Flat Spiral Coil
Hello, I am trying to model Flat Spiral Coil, but I am not able to model it satisfactorily. It will be really good if you can help me out in the same. Thanking you in advance. Sincerely, Ronak.
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weak constraint in" benchmark model of ccp"
Hi ,guys. I am confused by the use of weak constraint in model library ”Benchmark model of a capacitively coupled plasma" .more specific I don't understand why "J_total= intop1(-d(V_lm,t))" ,ie the...
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Which BC needed?
Hey there, I am quite new to comsol so maybe there is an easy way to do it. I have a pipe with an internal helix structure which is repeated after a 180° twist. I want to use this symmetry to save...
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Questions about "bouyancy water" model
Hi, guys I have been learning the "bouyancy water" model of the "model libraries" these days , it's a simple model——temperature differential produces density variation that drives the bouyancy flow in...
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Transient heat transfer
Hi everyone I'm struggling with a case of heat transfer from hot billet to a cold billet bay. I have started with a simplified model with no convection. The ultimate goal is to analyze thermal stress...
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Confinement losses in soft glass step-index fibers. Comparison with published...
Dear community, I am currently looking into the confinement losses with respect to wavelength for different fiber types: SIF, PCF, ... . To check my models for the simplest type (SIF) I found a...
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DBD plasma actuator model
Hello everyone, I am trying to study gas discharge at atmospheric pressure using a dielectric barrier discharge plasma actuator (2D geometry) consisting of two electrodes, one exposed to air gas at...
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Thermal expansion with temperature dependent CTE
Hi all, I want to model the thermal expansion of a structure made of two different materials whose coefficient of thermal expansion (CTE) depends on temperature. To do so, I defined two piecewise...
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Anisotropic diffusion coefficients in Maxwell-Stefan equation
Dear experts, Using Maxwell-Stefan equation for diffusion, I want to set anisotrpic values for the diffusion coefficients. This can be easily done if I use Fick's equation but it does not look...
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Time-stepping
Hi, I would like to run some simulations which use an exponential time step, and I have figured out how to set that in my "range" of solutions shown, but I was also wondering if there was a way to have...
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How to define the incident light area in Mode Analysis?
Hi all, I want to do mode analysis of a rib waveguide, as shown in attached figure (a). But the modes I got are not guided in the waveguide, as shown in attached figure (b). I think the incident light...
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Extracting Eigenvalues and Eigenvector using Eigenfrequency study
Hello, I was successfully able to extract the first N (~ 50) eigenvalues, using Eigenfrequency study and Solid Mechanics physics setup. I use the export option to write out the frequencies and...
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No-homogeneous initial condition
Hello I am trying to build a mass transport model that has a higher solute concentration in a region than in other of the same domain. Is this possible in COMSOL? How?
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Link two models PDE and Thermal Stress
Hi there, I am new in COMSOL, using the version 4.4. I am using two model. One is "coefficient of PDE(c)" and other is "thermal stress model". Both are time dependent. The variables I am getting from...
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Meshing a Square into 8 equal triangles
Hi, How would you go about meshing a square into 8 equal spaced triangles? I managed to go into free triangular 1 --> distribution This lets me set the boundaries on the mesh. When i set it to 1, i...
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Ivar Kjelberg- Problem on Joule Heating analysis over a thin geometry
Dear Ivar, (After patient waiting I had to direct the query to you,sir! ;) Dont mind) I am trying to simulate Joule Heating analysis for a very thin geometry (description- 4 domains over each other...
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running integration of variable in time domain
Hi everybody Short version: How to do a running integration/averaging of a time-dependent variable on a fixed length time interval? E.g. from time-dependent variable v I want to calculate a new...
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Generalized Laplace Equation
Hello everyone, Does anyone have any idea how to set up a Generalized Laplace Equation to a model? I tried to solve it using the Poisson's equation ( ∇·(-c∇u)=f ), where i put f=0 and the dependent...
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Surface to Surface and Ambient radiation, can't evaluate epsilon_rad
Hello all. I am simulating a hot-plate in vacuum that is at a certain boundary held at 400C and at another boundary thermally anchored to room temperature. Since the system is in vacuum, the only...
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