Help me. I have an exam on 27 of February (NMR)
I have to carry out a 2D axial-symmetric project that represents the phenomenon of nuclear magnetic resonance; I wanted to ask if any of you had a model already made or something to take a cue from;...
View Articlecalculate optical force by using maxwell stress tensor
I wan to model the scattering of a nanoparticle for calculating optical force ( gradient force ) based on maxwell stress tensor.but I don't know how to set the parameter in comsol, could you help me?
View ArticleInterior Impedance/Pair Impedance for the Pressure Acoustics, Boundary...
Hello,Would it be possible to add the Interior Impedance/Pair Impedance BC to the Pressure Acoustics, Boundary Elements Interface? From my knowledge of BEM I can't see any reason why it wouldn't be...
View ArticleAverage Current Density used in 2D model of Lithium ion battery
Hi, I have been trying to model a 2D lithium ion battery using different electrodes. How do I calculate the value of Average current density to be used? The 2D tutorial sheet takes -50 A/m^2, but they...
View Articlehow to transform a closed Parametric curve in a 2d surface
Hello comsol forumI am trying to simulate scenarios of 2d scattering of a cylindrical em wave from an infinitely long z-directed PEC with a specific cross section.I successfully done this for a...
View ArticleBUG in COMSOL 5.1 on parametric curve design
Hello forumI think i found a bug in comsol 5.1 regarding the parametric curve functionality. Specifically, i wish to design a rounded triangle with expressionsx(t)=0.28(cos(t)+0.2cos(2t)) y(t)...
View ArticleMaximum number of Newton iterations reached
I tried other ways like 'raise number of iteration', 'use more fine mesh'. But it have same error message and when I use more fine mesh, it's simulation time is tooo long (more than 12hr).=======...
View ArticleProblem with sign function sign(u)
Hello,I am trying to sketch a rounded square with the parametric curve functionality using x(t)=2.1sign(cos(t))(abs(cos(t)))^(1/2) and y(t)=2.1sign(sin(t))(abs(sin(t)))^(1/2), and i get a warning...
View ArticleHow to export coordinates of zero contour?
I use the microfluidics level set module to solve a time-dependent two-phase flow problem. I want to export the interface at all times. How to do this?Essentially I just want to export the coordinates...
View ArticleNot specifying boundary conditions for certain dependant variables.
Hi, I'm currently working on a system of PDEs using the Coefficient Form PDE module in 2D for my reactor design coursework. My system requires the coupling of multiple dependant variables with...
View Articlepermanent magnet (Nd magnet)
I designed the nd magnet.In magnetic flux conservation 1 , the z axis was set to 0.5030T.( Nd magnet)In magnetic flux conservation 2, air domain was set to relative permeability. (Air zone)Infinite...
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Issues with meshing domain with many lines
I'm trying to solve a problem where the domain is a unit cube with lines generated via a periodic voronoi tesselation. I require these lines for my physics. I am very often running into issues when I...
View ArticleHow to set units for spreadsheet interpolation functions
Hi everyone,I am using interpolation functions as part of my user-defined material of supercritical nitrous oxide.I created a single file containing all the necessary properties from REFPROP 9.1 like...
View ArticleHow to solve a diffusion problem with precipitation reaction
Hi,I want handle a dilute diffusion problem. During diffusion, precipitaion reaction may occure and compounds would form if concentration on the element is high enough.I am not sure how to solve this...
View ArticleHow to get a temperature value a one point and assign it to a boundary variable
i need to create a velocity for the moving mesh, this velocity takes the temperature value at (r=0) in the (2D axisymmetric model) and multiply it by a simple exponential function of r to give a...
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How to stop COMSOL Events at an exact value?
I am simulating battery cycling using the Events interface. The voltage limits are V_high = 2.45 V and V_low = 2 V. The events are working okay, but there is a problem that I have encountered multiple...
View ArticleProblem with zoom and rotate in graphics
I develop the application for my graduation work in Comsol Multiphysics 5.4. I want to place the geometry of my pyramidal absorber and the electric field next to each other and I don't want to open its...
View ArticleIn a Turbulent-flow k-eps (spf) CFD, how would I find the net moment of the...
In a Turbulent-flow k-eps (spf) CFD, how would I find the net moment of the air-forces on my body about a user-specified point? Similarly, how would I find the center of pressure (related).
View ArticleLinear voice coil actuator modelling
Hi,I'm trying to model a simple voice coil actuator in 2D and the magnetic feilds looks accurate. I also run current through a coil and try to calculate the resulting force on the coil. The results...
View ArticleHelical Resonator
Hi, I am looking for possible resonances of a helical resonator in a copper cylinder. Here I attached my file. By using eigenfrequency study in the RF package and setting up reasonable boundary...
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