Electrical machine 2D to 3D
Hello! I would like to extend my 2D model of a switched reluctance motor to 3D, to investigate the end effects, but I have some problems solving the 3D model. The 2D model works very well and has been...
View ArticleSupersonic Expansion into a Laminar Two Phase Flow
Dear all, I am using Comsol 5.0 and I am trying to solve a problem in 2D which contains a supersonic expansion of CO2 (Mach 1.19) from 2 of 25 micrometer holes into a 6.35 mm tube where water flows...
View Articlespecifying time step
Hello I'm new in COMSOL. I wanna solve a transient problem but I don't know how exactly set my time step. actually I got confusion between time step which would defined by study step and time step in...
View ArticleSymmetric Stress ,Without Fixed Constraint
Hi guys, I have a symmetric structure which is imposed by symmetric stresses , and i wanna know the displacement of top point of this model without any fixed constraints. But it cannot be solved...
View ArticleTime dependent Contact modeling with Automatic Remeshing
Hi I am trying to model a Sand grain which is pressed completely into a hyperelastic material (rubber). My sand grain has a diameter of 200 µm. I am using a prescribed displacement to move it into the...
View Articlesolving PDE with source term (right-hand side) as matrix from MATLAB
hi, all I am trying to use coefficient from PDE to solve helmholtz type partial differential equation. (I know there is helmholtz equation, but both module doesn't working) So, first I am using COMSOL...
View Articleinverted mesh element near coordinate
Hi dear IVar I want to see the mechanical changes due to flow of current through two parallel wires in COMSOL. To do this, first I used two "magnetic field" and "solid mechanic" modules. After getting...
View Article"inverted mesh element near coordinates"
Hi dear Ivar, Thank you for your helpful advices, Actually, I modified my model by your comments, and it was working correctly when I had chosen "extremely coarse, extra coarse, coarser" for mesh...
View ArticleComplex Band Strucutre - Acoustics/Structural Mechanics
Hi In a typical phononic band structure calculation done within COMSOL the procedure is to define Floquet BC's and do a parametric sweep of the wave vector over a particular direction in the...
View ArticleSimulating a coil with current above ground, no B field found
Hi, I am building a simple AC/DC model: a half space as air, a half space as ground and there's a two-turn coil in the air above the ground. I want to put a AC current into the coil and get the...
View ArticleDC discharge - Undefined value found in the stiffness matrix
Hi everyone, I’m trying to solve a time-dependent study on a DC discharge 2d model. I inserted some fictitious boundaries in the geometry in order to facilitate the creation of a mapped mesh, but when...
View ArticleLVDT design
HI IVAR, i am currently working in LVDT Design(Linear Variable Differential Transducer) particularly used for displacement measurement.. i have designed the mechanical model.. i have attached the file...
View ArticleIssues with Numerical Noise
I am solving a simple classical diffusion equation for 'c' with the diffusion coefficient being directional dependent (function of grad(c)). I am getting some weird results and numerical noise for the...
View Articlehow many boundary condition should be imposed on spatially first order...
I'd like to solve a 1st order differential equation like this in 1d domain: du/dx =u x in [0,2] u(0) = 1000 while I was using the General Form PDE in stationary , there are two boundary point in x=0...
View ArticleAC/DC simulation_Space charge added to spheres
Hello, I am new to the AC/DC modelling using Comsol. Basically, I have a 3D unit block with 8 nano-particles inside. Each nano-particles is consisted of four different layers. I applied the positive...
View ArticleEvaluate derived values
Hello, In the Results node, I would like to evaluate several expressions of derived values simultaneously in the same table. For example, I have to evaluate the Surface Maximum of stresses sx, sy and...
View Article3 D Electrostatic Force Calculation
HI, I am a newbie to Comsol, and i am using 4.3 version and working on a mems gyroscope. i need to calculate electrostatic actuation force from the model,i am using a comb drive structure as an...
View Articleinput configuration time discrete solver
hello, how can i input parameter or variables to config the time discrete solver, especially the parameter prevlevels? What is the max number to store previous data? Thanks. jojo
View ArticleUndefined value found in the equation residual vector.
I am trying to model a pem fuel cell. Although I have entered all parameters and values, i have some errors as follows; Undefined value found. - Detail: Undefined value found in the equation residual...
View ArticleImport results from a different simulation as a boundary condition or solve...
Hi folks, I am simulating a pipe flow with 2 sections, and due to the dense mesh, the cluster is running out of memory. So I was wondering: is it possible to simulate the first section and save the...
View Article