Hi everybody,
I've just started working on COMSOL MPH on an Acoustic/Structure Interraction. After repairing the geometry, i wanted to mesh it to know if it's well repaired, but i had several errors and warning due to narrow regions et small edges ... , the geometry is quit complicated so i wanted to know if i can have an advise please , just to help me start the work properly
Nb: I'm a beginner on the field
Thank you for your time
Hello everyone,
I am not too familiar with COMSOL, so it may be a basic question.
I am working on electrostatics field and I would like to evaluate the electric field along an insulator. Therefore, I draw the insulator in 3D model and put it on a big cube, so I could simulate the air around my insulator.
The problem is trying to generate the mesh of this, the program presents the follow message "A problem occurred when building mesh feature 'Free Tetrahedral 1'". The insulator has a complex geometry. However, when I try to simulate only the insulator, the mesh could be generated. The cube presence is important in this case, so I cannot just take it off.
Does anyone could help me with that? Thanks a lot.
Hello, we are new to COMSOL and got 2 questions: 1) Is it possible to export 3D model from scanner directly or we need to use CAD software for data processing first? For example, we are using Artec Studio and seems like we have to use another CAD software for post-processing before export to COMSOL? 2) Half of our scan are have .stl format. Others are .obj, which are not supported?
Thanks for any help.
I'm trying to model a solenoid around a permanent magnet and try to analyse the voltage/current induced in the coil by moving in to and fro motion in 3D geometry. How can I visualize this in comsol5.3. Also how can I draw a toroid in comsol?
Hi,
I'd like to import an stl file into a COMSOL simulation, and the online tutorial says that COMSOL supports this file type. However, when I try to use the import function on the Geometry toolbar, the file types that COMSOL gives me the option to import are Mesh, COMSOL Multiphysics file, and DXF file. When I browse for the stl file I want to import, I can't find it where it's saved. Any help in changing the COMSOL settings to be compatible with this file type would be appreciated.
Thanks, Henry
Hello!
It's like I am solving transport-diffusion model for a 2D domain. I have made the following observations which I cannot figure out. 1.) If I use only triangular mesh without any boundary layers. Then I get double derivative say cxx equal to absolute zero everywhere which is weird. It's like it's not even calculating the derivative. So, if that's true how it can solve the Laplacian term in the model. 2.) If I use triangular plus boundary layer. Then cxx is evaluated only at the boundary layer. Rest domain is absolute zero. And I have set relative tolerance 1e-6. So my solution is converged. But inspite of this fact I am not getting cxx+cyy=0 or close to 0. Why? I am unable to explain. 3.) If I use triangles plus second-order discretization. Now I am able to get cxx all over the domain. Why? 4.) Lastly, if I use quads as my meshing elements I can define cxx at every point. However, cxx+cyy is not close to zero everywhere. It would be great if someone could help me to figure out these observations.
Best Regards, Ayush
Hello,
I have a circular tube that is approximately 150 mm long and the last 15 mm of the tube (the tip) will deflect 30 degrees to -30 degrees. I have a velocity inlet and a pressure outlet. I want to simulate a fluid flowing through the bending tip. The tip motion is to be defined from an external device and is not due to fluid forces. I would like to examine the effect of tip angle on the exit flow rate as well as examine the exit flow velocity distribution. I have attached a picture detailing how the tip will displace during one oscillation. The red dotted lines indicate where the bending will take place. I believe I would need to define a moving mesh with a prescribed deformation for the bending region. Any suggestions or advice on how I may go about this would be greatly appreciated. I am using COMSOL 5.3a.
Regards, Will McKinney
I am trying to mesh a 3D domain but no matter what meshing settings I choose I am getting the following error:
Failed to analyze local face topology. - Face: 12 Invalid curve or surface.
In the file, the face in question is the "inner" curved face of the spiral coil, and I suspect the problem is somehow caused by the way I've attached a "lead" onto the end of the spiral by making a rectangle, unioning them and allowing COMSOL to repair the gap, but I'm not sure how else to approach it.
No other domains have yet been meshed, and a search on this forum for the error message did not reveal anything. I've attached the mph file in case anyone can help me out!
I am using the general form PDE option from the mathematics package to solve some equation and I would like to use adaptive meshing. The default error indicator is sqrt(comp1.u5x^2+comp1.u5y^2) (my dependent variables are u1-u5), however I have not been able to find any documentation on what this comp1 variable is. Does anyone know?
Thanks in advance.
Hi all,
I'd like to simulate an assembly process (soldering) in microelectronics packaging which follows these steps:
1) A substrate and a metal lid are separately heated to temperature T1 2) The substrate and the lid get connected by a thin layer of solder 3) The whole package is cooled down to T2
I'd like to see how the residual stresses look like in the whole system after the assembly process. I'd be thankful to know your thoughts.
Regards, Ben
Hi All,
I'm trying to model a toroidal inductor in 3D with a rectangular cross-section. I've successfully made the CAD model, and am trying to import it into COMSOL. However, I'm getting internal error code 900, and I suspect its because since I patterned a single turn to get the toroid shape, when the turns meet, they dont match nicely. In SolidWorks, everything looks great (the wires are circular and the separate turns meet nicely), but when I imported them into COMSOL, it seems that COMSOL made the circular cross section of the wire hexagonal, and the separate turns now don't completely overlap. Is there a way to better resolve this import, and if so how?
I can include a picture of this nonoverlap if that would make it more clear.
Thanks, Henry
I'm getting the following error message when I try to mesh a toroidal inductor with a rectangular cross-section, imported from an external CAD software: "Boolean Geometry Operation Failed" (it is a very complicated model as it is many-turned and tries to approximate a geometrically thin wire). Can anyone explain what the most likely fix is, or where I can look to try to successfully mesh my model?
I can provide any pictures or files if it would make my question a bit clearer.
-Thanks, Henry
Deal all,
can you explain how to understand the size of stiffness matrix which is exported from comsol,
for example i have a 2d cantilever beam, discritized with nel_x x nel_y=20 x 10 => nnode_x x nnode_y = (20+1) x (10+1)=231 nodes, and ndofs=231 x 2=462 degree of freedoms,
so i expect the size of stiffness matrix will be K(full)=462x462, but the size exported from Comsol is: 1322x1322
you can following the matlab file for runing in Comsol server;
Why does COMSOL give me this warning when I import geometry from Solidworks? I have the necessary licences and I am able to import, but cannot import an STL file as a solid, only a mesh. What must I do differently to import my geometry as a solid not a mesh?
Hello,
I am working on a geometry that has a very high aspect ratio and need to create mapped mesh for one of the domains and free triangular mesh for the others.
I am facing couple of issues:
When trying to mesh one of the domains with a mapped mesh, it says "Isolated element found" or "Inverted element". How can I solve this issue?
On meshing the entire domain with free traingular mesh and using Laminar Flow and Heat Transfer modules, the computation doesn't terminate and gives an error: "Singular Matrix Found" What might have gone wrong?
Thanks in Advance!
Hi, I'm trying to reconstruct a model of cytokinesis in this paper
I've tried axisymetric model in COMSOL using the remesh of a single static step in the adaptation and error estimate as the following. However, I have very limited control of the remesh configuration, only the maximum element number. I'm wondering if it's possible to have several criterions for remesh like the maximum and minimum element size of the remesh? https://ibb.co/nn99Oe The figure after manually adjust the range of value is like this, https://ibb.co/k1Y0wz
Another critical problem is I don't know how to do multiple static steps that inherit the stress and strain from the previous remeshed step so far. I've found a stress free nodal update here, but what I want is to inherit stress and strain from the original configuration and keep each analysis in a static sense. I don't want a time dependent physical problems. Could anyone give me some advise about how to do that?
One of the point I found is that for static problem, when I disable the BC's by modifying the physical model tree, COMSOL always just report error, " - Feature: Stationary Solver 2 (sol1/s2)". My COMSOL window setting is like this. This doesn't happen in the time dependent analysis when I play with the heat transfer problem. Does anyone know what's wrong with my setting? How to do multiple static analysis steps use the remesh to update the mesh at each step while inherit the stress and strain in previous step as initial conditioins. Please help and let me know, thanks.
Hi I'm working on thin film solar cell simulation on COMSOL 5.3a, and in order to overcome the incoherent propagation of light in the thick glass substrate (2mm), I'm going to use phase elimination approach. https://www.comsol.com/paper/download/182423/aampa_paper.pdf
the problem is by modeling a dynamic geometry as function of wavelength and refractive index, which is a function of wavelength. how could I include the material property and the wavelength in the geometry? the method in the paper gives an "unknown function or operator" for interpolation function and "unknown model parameter" for lambda0. and how to generate different mesh at each wavelength and consider those changes, geometry and mesh changing at each wavelength, in single study computation?
thanks
Hi,
I am trying to calculate the stress due to a point load in 3D block geometry. When I am using a mapped option mesh, no matter which size of mesh that I choose, comsol always return an error "no mesh on domain 1. Do not find systematic matrix.". I set the mapped mesh for entire geometry.
But when I change to use a free tetrahedral option for generating the mesh, choosing the extremely fine mesh size, my model works. But if I try to design the element size as 1 km, comsol crashes.
Did anyone meet the same problem before? I want to use 1km*1km for each element, but the model never works.
Can anyone help me?
Thanks!
Hi
I have a situation, I have a 2D code that works fine but when I extend the code to 3D it always has NAN or singualr matrix issue?!?!
Its Navier stokes and PNP eqaution plus magnetic field, the problem is with magnetic field (ampere law) that casue sigular matric in 3D,
can anyone please comment, I played with mesh did nt help, all BCs are same as 2D...please help
Thanks
Hello, I am trying to replicate the results from a paper. I am having problems with the mesh. I have attached a photo with the geometry and a description for the mesh.