Hello, I'm attempting to analyze an assembly of two electromagnetic multi-turn coils each with an iron core. I followed the instructions in the video "COMSOL webinar - modeling coils and electric devices" https://www.youtube.com/watch?v=n7xhNFzWQ1U, specifically the helmoltz coil construction. However, the computation time was taking over a half hour to compute so I'm wondering what I did wrong. Any assistance would be appreciated, I attached my mph file for inspection. Thank you, Michelle
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Multi turn Electromagnetic Coil Assembly
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Beam-solid connection in 2D
I am a bit stuck with the attached simple model. I have a rigid circle and a beam rigidly welded to it at one of the quadrant points. I am pulling on the free end of the beam with some known force. I am curious by how much the circle will rotate (because my force is also exerting an effective torque on the circle relative to its center). The center is held in place via a spring foundation which should stretch by a known amount since I put in a known pulling force and a known spring constant but there are no rotational restrictions on the circle except general force balance, i.e. no torsional springs or anything like that. Despite the simplicity of the model, it refuses to converge which tells me I am missing something. Any help would be appreciated.
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How to use external current density in racetrack coil
Hi all,
I need to analyze Electromagnetic force of racetrack coil with time dependent. To make this model, I use external current density. It has been confirmed that the external current density can be properly analyzed by time dependent analysis of circular coil. By using like those formula. Ix = I0-y/sqrt(x^2 + y^2), Iy = I0x/sqrt(x^2 + y^2), Iz=0
Now I try to analyze racetrack coil using external current density but I can't. I attached the file. Please give me your help and advice.
Thank you
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ELECTRIC FIELD DISTRIBUTION
hi all, i want to calculate electric field distribution by finite element method using comsol,can anyone help me?
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Diffraction Grating
Hello, I am trying to simulate difraction grating and to extract intensity vs the angle after the grating. I managed to create a diffraction grating both with ray optics and wave optics, but I am strugling to get the intensity vs angle (not incidence angle but output angle). Would appreciate if someone could direct me towards the solution of that problem.
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flow rule and hardening work in ottosen model
I am trying to model a piece of concrete and I need information about how the ottosen concrete model in comsol adopts yield surface, pastic flow and the work hardening; someone has information about this or where to look?
Thanks for all
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1/r in 2D-axisymmetric volume force: How to deal with it on the axis?
Hi all, I'm simulating ferrohydrodynamics and I'm trying to impose a Volume Force in the Laminar Flow physics. This volume force has a part like this:
((1/r)(d(r(d(A,r))^2,r))+d(d(A,r)d(A,z),z))mu0_const
where "A" is the magnetic scalar potential. When I plot this term, the closest layer to the axis has not been taken into account actually (take a look at the attached image please, the black vertical line is the axis.) How can I prevent this problem? I have instabilities on the axis because of this issue. Thanks
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Eigenfrequencies in Frequency Domain, Modal
Dear Comsol forum,
I am trying to analysize the energy distribution of multiple eigenfrequencies of a simple metal object. I think the "Preset Studies for Selected Physics Interfaces" - "Frequency Domain, Modal" is for this kind of problem. However, I don't know how to set the searching frequencies on "Step 2: Frequency Domain, Modal" from the result eigenfrequencies found from "Step 1: Eigenfrequency." This means that I don't want to manually input these eigenfrequencies in the Study Settings - Frequencies in the Step 2, but (1). compute the eigenfrequency study (2). get those frequency result values and set it in Step 2 and compute the 2nd study, and calculate resultant energy. If there is any document that I could read about this, please let me know. Thank you very much.
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Help
Can anyone explain why this happen??
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Deformation and Capacitance of Structured PDMS Dielectric
Hi COMSOL Forums,
I'm currently working on a simulation of capacitors with structured PDMS as a dielectric. I want to model the change in capacitance with a change in boundary load/pressure. My current model assumes that the top boundary of the PDMS has an applied voltage and applied boundary load. At the bottom of the film, there is a silicon film which acts as ground and a rigid base. The structure for the PDMS film I have currently selected is a triangular shape.
I have the mechanics portion of the simulation solved. I am using a stationary study and sweeping boundary loads. The geometry is constructed as an assembly. The deformation is modelled using contact-pair & solid mechanics assuming/forcing linear strains. (Currently, I do not have the non-linear mechanics package.) The deformation of the dielectric under pressure can be seen clearly and is quite large. The side walls of the triangle should come into contact with the base. I have also been able to successfully couple electrostatics in these domains. The simulation only takes into account the PDMS and silicon film but doesn’t include the vacuum/air surrounding the structure.
I would like to know add a vacuum/air environment in the remaining space between the PDMS and base. I have tried adding a deformed mesh to the remaining space but my solution does not converge. I'm not sure how I can couple the physics and deforming mesh together. Does anyone know what may be causing my problem and a possible solution?
Please let me know if what I am saying is unclear.
Thanks for your time and help, Michael
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Can the specified displacement and the specified velocity be used simultaneously in solid mechanics?
Can the specified displacement and the specified velocity be used simultaneously in solid mechanics?
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Modeling Wettability in Porous Media
Hello there,
I am a new user of Comsol. I am currently working on the mass transfer in the postive electrode of Li-O2 batteries. I want to perform the following steps using Comsol: 1. Creating a porous media with a certain pore size distribution 2. Setting either hydrophobicity or hydrophilicity of pores in the porous media
I really appreciate if anyone can help me with those two steps.
Thank you! Fangzhou
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simulation electric field distribution of high voltage on a rotating machine with high voltage supply
Hi, Currently, I have project in build a machine consists of motor , high voltage supply and metal syringe. The process of machine is metal syringe will be attached to the motor using insulator coupling and high voltage will be connected to the needle syringe. the schematic diagram as an attached file. The problem I had is when motor is rotate and positive high voltage supply connected the metal syringe while negative to the aluminium plate during the process, motor and high voltage will stop.
I already done simulation electric field potential high voltage supply but without motor.
My question is
- How to do simulation on high voltage electrostatic breakdown voltage?
- How should I input the rotating motor to the simulation?
- Is it using rotating machine 3D tutorial application?
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Errors "JavaNullPointer" when inputting matrix with multigrid preconditioner
Hi everyone, I'm using Livelink(TM) for Matlab(R). When I tried to run the solution after inputting matrix to an electrostatic model's stationary solver, the error came out with "java.lang.NullPointerException" and the server flashes and disappeared. I've checked a few settings and found that it was probably about the multigrid preconditioner. I think the InputMatrix node cannot work well if the stationary solver uses multigrid preconditioner. But why? Can anyone tell me? How can I solve this problem?
The picture below is the example commands I use. Maybe help understand.
So much thanks
Fei
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A system of nonlinear PDEs with Changing Geometry
I am new to Comsol. Before I start reading tutorials, I wanted to make sure that Comsol meets my specific modelling problem.
Can Comsol solve a system of nonlinear PDEs which its geometry changes? For example, to model a reaction-diffusion system in a growing cell, I want to model the cell as a disk and this disk becomes larger over time or even perhaps it divides into two smaller disks.
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Bending a thin block around a cylinder
Hello all, Is there anyway to bend a block around a cylinder in comsol?
Thanks, Shaghayegh
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how to obtain dataset from a smaller volume of spherical region
I have designed a coil system (4 maxwell coils placed adjacent to each other orthogonally to produce gradient fields) which is establishing a magnetic field in the air domain. Now i wish to get acccess to the field dataset within a smaller volume of spherical region , so that i can plot it in matlab and find the field equation within the sphere.
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Modelling fluid flow plus membrane deflection
Hi all,
I am new to comsol community and I am facing a simulation of a membrane/wall deflection over a microfluidic channel. At this moment, I have a microfluidic channel which is formed by a domain filled with fluid (no wall thickness, just the path the fluid follows). At some point of the channel (rectangular cross section), I have a 200 micron layer which I would like to deflect upon mechanical load.
I have always simulated microfluidic chips being the chip as the domain where the fluid flows, not considering any wall thickness. It is now, that I want to simulate mechanical actuation over a 200micron thickness wall that I wonder how I should set the walls (thickness yes or no?). In addition to this, is it possible to do it with the basic functionalities of COMSOL multiphysics 5.4? Or should I get the specific structural mechanics or MEMS module?
Thanks in advance, Pablo
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Impact Testing
Hello!
I am rather new to COMSOL and I need assistance with conducting velocity impact testing simulation within COMSOL, where I am trying to simulate impact testing from a Split Hopkinson Pressure Bar (SHPB). Knowing there will be a dynamic non linearity development within the specimen, how would I account for that and would I use the time dependent study to see how the specimen deforms? I know I can start with designing the CAD part, adding it to COMSOL, and then add a point load to the specimen; however, I would like some help with deciding how to add the time dependency as well as the impact velocity of a projectile to the face of the CAD part.
I would like to use this model to understand the dynamic modulus vs strain and the strain rate of the material, along with obtaining the illustration of the deformity using COMSOL.
Thank you,
Stephen Palmer
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Negative admittance in electric current simulation
Hello,
I'm trying to simulate electrical contact through oxided metal, and i use the contact impedance boundary condition as the properties of oxided layer. and i use both direct and iterative solver. however, the results came back showing that the admittance is negative at some frequency range. it doesn't make sense.
Anyone help me.
kind regards.
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