Urgent : Boundary layer meshing problem
Hi, I need a help to understand the boundary layer meshing in COMSOL. I have an axisymmetric model of a simple cylinder of diameter radius 6 mm. For the penetration depth of 0.14 mm at the outside...
View ArticleHow to define a dispersive material as a function of COMSOL predefined...
Hi: I defined a dispersive material function (frequency dependent relative permittivity) in Global Definition. Function name: LD_real Expression: ff E-14+0.6 Argument: ff Argument unit: Hz Function...
View ArticleModel saved in 4.2 need to be saved in 4.1
hi friends! i am trying a model of air and hydrogen mixing phenomena. i was using version 4.2 now i am using 4.1. The model i have, is saved in 4.2 i need it to be saved in 4.1 so that i can run it ....
View ArticleBoundary current source vs electric potential source
Hello, I have a question about the AC/DC module -> Electric currents. I made a simple model of a spherical homogenous volume conductor. Inside this sphere I added a cylinder along the 3-axes. On the...
View ArticleHow can I get the field distribution after the incident wave is subtracted?
Hello! I have a question need your help. I calculate a grating model in comsol4.3, and is illuminated at normal incidence with a TM-polarized plane wave. There question is how can I get the...
View ArticleBest way to switch on fields in time-dependent simulations
Hi, Is there a kind of recommendable way of switching on fields in transient emw-simulations. Right now, I'm using the step-function, included in Comsol, and I have some problems with the converge of...
View ArticleNegative 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....
View Article3D Natural Convection Hot Plate
Dear all, I am having trouble with modeling natural convection for a while. I have started with a very simple case of having a hot plate at 150 degC surrounded by room temperature air and want to...
View ArticleBias Current Density
hi!! I need to generate 1.5 Tesla magnetic flux out of a rectangular block. what value of current density (J) should i use? what is the constitutive relation to find the required current density...
View ArticleMeshing errors
I just stated using COMSOL and I'm trying to build two helical coils stacked on top of each other with a ~5cm gap. Whenever I attempt to build the mesh I get the error tree, failed to generate mesh for...
View ArticleWhat kind of strain or stress should I be reading in the results for...
Hi, I am doing a piezoelectric simulation and using a force, I have displaced the piezoelectric cantilever. However, in the results section, I'm not sure which type of strain should I be looking at as...
View Articleadiabatic air compression
Hi, I want to ask what kind of modules I need to realize adiabatic air compression. I am not sure weather I need to define compression heat using ideal gas law or some modules can consider compression...
View ArticleHow to reduce the model file size
Hi, I built a 3D heat transfer, time dependent model. After simulation, the model file goes beyond 5G. Is there anyway I can reduce the file size? I only care how the maximum temperature changes with...
View ArticlePlot on of field on plane, RF MODULE
Dear all, I need help. I have model with two spheres (attachment). I want to plot electric field enhancement but in one plane for one wavelength. I know how to plot electric field for many wavelength...
View ArticlePlot on of field on plane, RF MODULE
Dear all, I need help. I have model with two spheres (attachment). I want to plot electric field enhancement but in one plane for one wavelength. I know how to plot electric field for many wavelength...
View ArticleWeak Boundary on COMSOL 3.5 a COMSOL 4.2a
Hi, I am chemical engineer of the Mexico City. In the work: square_droplet_2Daxi_reset.mph, that this in the comsol version 3.5a, in the tutorial in the step 7: Open the Equation Systyem > Boundary...
View ArticleParametric Sweep and exporting data
Hi, I'm doing a parametric sweep in a model with a geometry that depends on the same parameter wich I sweep. I run my parametric sweep and works well (the solver remeshes the model for each value of my...
View ArticleDefine a selection from the solution
Hi, I am solving a two-phase system and I want to know, how can I calculate the time-dependent rise velocity of the bubble (in the file below)? In my case the domain selection is not possible because...
View ArticlePlasmonic Waveguide
Hello every body. I am trying to simulate a simple plasmonic waveguide in "2D Mode Analysis" to calculate "propagation length" but I have confused. because the conducted result (2.6um) is different...
View Articlewhat does the "exclude algebraic" error estimation option do?
I'm working on a time dependent convection-diffusion simulation. The Peclet number is 10^3 to 10^4. The maximum Reynolds number is ~10. The solution tends to diverge at a point where the input velocity...
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