Negative 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 ArticleScttering problem using comsol4.2
I wanted to calculate scattering absorption cross section and thereby extinction for a nanoparticle. I am not sure how to go for that in comsol4.2. Can anyone please tell a basic flow to accomplish...
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 ~100. The solution tends to diverge at a point where the input...
View Articlemodel works with identity pairs but not with contact pairs
Any tips on what I am doing wrong in the attached axisymmetric model involving a titanium part with a rounded top that supports a nylon liner that fits inside a titanium "cap"? An approximate image of...
View Articlea time dependent matlab function
Hi I'm trying to make a time dependent time function to input as a boundary condition in comsol. I have a vector in matlab and each line is applied in a determinated sampling time in the boundary...
View Articlemodeling a torque measurement setup
Dear All, I am modeling a test setup that is used to measure the torque of a rather unconventional electrical machine called the lateral stator machine. You can see this machine in the attached file....
View ArticleDifine Herschel-bulkley parameters
Hi I'm trying to understand how can i define shear stress parameters for Herschel-bulkley model in Comsol 4.2a The stress expression for this model is: stress = yield stress+m*(shear rate)^n Any...
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