Enforcing variables to be greater than or equal to zero
Hello, I'm modelling diffusion through a porous medium with adsorption. The main dependent variable for mass concentration tends to go below zero which is not true in reality. Is there a way to enforce...
View ArticleHelp me please! how to draw the magnetic field lines in 3D, as
Hi all! I need to add the magnetic field lines (and possibly add metal bars between the head and emitter) to the model 2190 Absorbed Radiation (SAR) in the Human Brain. PS Since I'm a beginner, then I...
View ArticleTemperature mapping with Model Coupling
I wish to generate temperatures in a model and subsequently map the temperatures them to a similar model in a different study. The two models will have the same geometry. However, the model will be...
View ArticleMeshing of multilayered Hemispherical 3-D geometry and Time dependant heat...
Hello Sir, I am trying to simulate a 3D tissue model, which is hemispherical in shape. I am imposing a sinusoidal heat flux on the top curved surface of hemisphere. After solving the transient bio heat...
View ArticleHow to write Nabla function in comsol 3.4
Hello, Can anyone tell me how to write nabla function in comsol 3.4? What is the syntax for this function? I wanna use it for dielectrophoresis and there is a term where I need to find the gradient of...
View ArticleDefining a Piecewise function of two variables
Hello, I am trying to model NMR diffusion in COMSOL 4.3 and need to define a function beta at three different time intervals as follows: beta = gyro*(g*x) (0 < t < 0.016s) beta = 0 (0.016s < t...
View ArticleHow to generate a "Join Data" set from parametric steps?
How to generate a "Join Data" set from two stationary and parametric steps? Hello everybody. Does anyone know how to merge two solutions when one of them is the continuation of the other? For instance,...
View ArticleSimulation of the magnetic fied
Hi, I have one physical NdFeB magnet and I need to simulate this magnet in Comsol 4.2a, but I dont know exactly how to do it. I know these parameters of the magnet: Remanence Br = 1380 mT Coercivity...
View ArticleMaxwell stress tensor integration
Hi everyone! I'm still trying to compare the electrostatic force calculated by the expression (F=0.5*epsilon*V^2*A/g^2) with the result coming by Maxwell stress tensor in COMSOL. I used the suggestion...
View ArticlePlease help! (error: Undefined value found)
Hello everyone, I’m working on the following model from Comsol library: Batteries and fuel cells>>ht_pem. When I change the geometry to a more complex one, for example using two or three...
View ArticleEigen-frequency analysis of metal grating
Dear all, For a metal grating (see attached Structure_Reference.jpg), now I would like to analysis the dispersion relationship of surface plasmon wave supported by a metal grating, which propagates...
View ArticleHow to know a material's parameter value
Hi people, i have a newbie question: in my heat transfer simulation i'm using a wood block (kingwood of Comsol material database). If i look the parameters, the value of density rho is not indicated:...
View ArticleHeat Transfer in Soils
Hi, I am a comsol user and I want to have a 2d axisymmetric model. In my model, I have a soil sample that I put a steel bar in the soil. I want to heat the steel bar with a constant temperature 500(k)...
View ArticleConvergence of Solver with Hyperelasticity - Problems
Hello, I've modeled a cantilever beam composed of Magneto-Rheological Elastomers (MAE) that bends when subjected to a magnetic field. The MAE used in the model currently uses a linear elastic material...
View ArticlePlease help me find how to achieve this function.
It seems to be a simple problem but I can't figure out how to make it. Description: a 2d transient model of a square is built, the left, bottom, and right side is thermal insulation and the top side is...
View ArticleSimulation of a floor heating
Hi all, I want to simulate a floor heating in a 2D modell. Floor heating systems release about 90 % of heat in the form of radiation and about 10 % in the form of convection. So is it possible to take...
View ArticleHow to change equation during a transient solution in V4.3
Hello everybody, I am simulating a transient solution by using transport of dilute species. I would like to change the equation during a transient solution and use the initial value of simulation 2...
View ArticleChange coordinate axis label
Hi Guys, Does anyone know how to change the coordinate axes labels in COMSOL 4.3? As we know, if we have a 3-D model and click 'Default 3-D view', we can observe that X axis is in the upper right...
View ArticleThermal Conductivity as a function of temperature
Hi all, I am trying to include thermal conductivity as a function of temperature in my model but its giving me error 'inconsistent unit'..let us say the function is -1.27E-9*(T)^3+8.09E-6*(T)^2-...
View ArticleRotating machynerry with rotor flow
Hello I would need to deal with this problem. I need a rotary device that had a rotor with one piece in the shape of a hollow ring which rotates to fill the metallic dust magnetic materials. But there...
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