Hi，
I am new to Comsol and know very little about different features of the software. When I want to form a grid by sweeping, the software prompts for an unsupported link surface topology. what should I do? thank you.
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Sweep forms a grid
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Export data from surface of a sphere
Hello all, I have built a model and I am trying to measure the field in a specific volume. Can we export our data from a surface of a spehre instead of a whole cube? is that possible?? Thanks Belal
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In (ec) analysis, how can current along edges of the meshes be determined?
Hi,
I run a frequency domain, electric currents (ec) analysis to find the electrical voltage and current distribution in a 2D non-uniform object. My goal is to export the voltage of each "vertex" and current along each "edge" of all triangular mesh elements.
Using 2D surface plot, I can plot and then export voltages of all "vertices". Is there a way to export currents of "edges"?
Note 1: I can export the x and y components of the current densities at vertices. However, for each vertex, N many (N>1) pair of x-y current density values are generated. It looks like N is equal to the number of neighboring vertices connected to the vertex of interest. I am not sure which current density pair corresponds to which vertex. Therefore, I cannot derive the edge currents using the vertex current.
Note 2: Quality -> no refinement, smoothing -> none, recover -> off
Thanks. Best, Hakan
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copy mesh to a component in a higher dimension
Hi, I'm trying to copy the mesh created on a 2d surface (obtained from a cross section of my 3d model) to the same face in the 3d model and then extrude the mesh to all the domain. I'm trying to use the tool "Copy" to copy the mesh from the 2d surface to the source face in 3d, but I've not totally understand how to do it. I'm following the instruction found at this link (in italian):
https://www.comsol.it/release/5.1/mesh-and-geometry
I'm using Comsol 5.3
All the best, V.
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What's the reason for this mistake" Inscribed diameter not implemented for this mesh element type."
I want use comsol software to simulate the model. That is about the Ultrasonic gas flow measurement .The theory is the time-of-flight or transit-time method to determine the flow speed.
I use the CFD physics and Convected Wave Equation. The first step I did in the modeling procedure is to establish a realistic background flow. This flow is taken to be stationary. Then, I compute the Convected Wave Equation.
The software points out one error
It tells that Inscribed diameter not implemented for this mesh element type.
I don't know the reason and can't find useful information in help. So can you tell me that what's the reason
thank you very much
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Magnetic domain refinement in electrical steel by laser scribing
Hello I want to model the laser-material interaction of a grain in electrical steel being cut in half, how would I model the ablation of the steel?
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Unable to Mesh Certain Domains due to "Unsupported Topology at Vertex"
Hey all,
I've been trying to mesh my model for a while now, and haven't been able to do it.
My model consists of a nerve with a stimulating cuff electrode around it, and everything is surrounded by saline. Due to the small size of the nerve, I've been using swept meshes.
The first issue I ran into was that the saline can not be meshed using a sweep since it is not a uniform shape the whole way through.
I've seen that you can combine a free tetrahedral mesh and a swept mesh somehow by meshing the surfaces individually, but I wasn't able to figure that out. Any help there would be appreciated.
To try and circumvent this issue, I partioned the saline into shorter segments that could each be swept individually, but now I'm getting a new error: "Failed to create swept mesh for domain. Unsupported topology at vertex." The point where this is happening is where two of the partioned saline domains meet along with a 3rd domain. I'm not sure what's causing it.
I'm really not sure where to go from here. Any help would be appreciated.
Thanks in advance!
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Successive load application in solid mechanics
Hello!
I'd like to simulate the deflection/deformation of a laboratory two-axes mirror mount (tilts a platform in two directions) milled out of a single piece of metal, so i thought of a one-body-problem.
In a first step, i fixed the mounting surface and applied a force on the first linkage surface. The results were as expected.
However, for the tilt along the second axis a force relative to another reference plane needs to be applied, i.e. between faces that were already deformed by the first step. Thus the definition of fixed faces changes between the two steps.
How can i use the results from a first calculation as initial conditions for my second calculation (if needed)? I read about using a moving mesh or adding a second study step, but its unclear to me what strategy should fit best for my case.
Big thanks! Maik
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Why are my meshes look weird?
I have this simple mesh where I have a bulk with coarse mesh and a boundary with fine mesh. Why do I get this weird looking mesh? Please help! Thanks!
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How to save computational time for transient CFD problem
Hi everybody, My model aims to couple fluid flow in the free channel (wellbore) and porous media (formation) for a time-dependent study, and the problem is that the computational time is very large.
I attemped to deal with this problem with respect to mesh and time-dependent solver (tolerance and time stepping). Using a coarser mesh and increasing tolerance are effective methods to reduce computational time, however, mesh refinement study is needed and tolerance should not to be too large for accuracy.
I am struggling about how to increase time step size as the simulation time increases. But the time step size did not seem to increase when I increased the simulatiuon time field from (0,1,10)min to (0,1,10)h no matter I used adaptive BDF or manual time stepping. Could someone give me some suggestions?
Thanks in advance!
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Meshing of complex membrane structure
Dear I am trying to mesh a membrane which consists of three different domains (External, Medium and Internal ) and want to draw mesh convergence plot of my geometery to identify at what mesh property it converges. Medium domain is suppose to be sensitive that's why It must be mesh very finely. I tried tetrahedral mesh at each domain separetly. Also I tried Triangular mesh with swept command. For 3D how can I draw convergenece curve, I don't have any idea. Although I watched videos as well but did not find any particular method to do so. Using parametric sweep I sweep the element size of mesh and plot one of eigenfrequency corresponding to sweeping mesh elements/ Result obtained is shown in attached file. It shows from extreme coarser mesh till Normal it convergences which is not correct and at fine mesh results are deviating alot specially at extremely fine mesh. I want to draw a convergence curve for my geometry in comsol. If anyone has idea, Please comment
Thank you for your support.
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Mapped Meshing
Hello all great minds,
I am trying to simulate a simple 3D thermo-mechanical model, Initially I solved the model using tetrahedral elements and now i am shifting to mapped one, just to see is there any change in results. but unfortunately i am getting an error mentioned below. Can anyone help me out to know the reason for this error. I tried changing boundary condtions but still the same message appears with different boundaries.
Thank you very much for your valuable time.
Sujit
Failed to evaluate Jacobian of operator. Failed to evaluate Jacobian of operator. - Operator: mean - Geometry: geom1 - Boundary: 3 Mean operator requires a meshed adjacent entity of higher dimension. Failed to evaluate Jacobian of variable. - Variable: comp1.ht.d - Geometry: geom1 - Boundary: 3 Failed to evaluate Jacobian of expression. - Expression: dvol_spatial(comp1.ht.ds1.rfluxcomp1.ht.d) Failed to evaluate Jacobian of expression. - Expression: (comp1.ht.ds1.rfluxtest(comp1.ht.ds1.Tvar)comp1.ht.d)*(dvol_spatial)
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Optimization for residual stresses in metal ceramic assemblies
Hi, I am new to Comsol and I'm trying to simulate the resulting thermal stresses in a metal ceramic assembly. I think the thicker the copper layers the higher are the residual stresses and the larger the layers the higher are the residual stresses, But if I try to simulate I get weird results. Maybe it has something to do with the mesh, I wanted to change the mesh from tetrahedral to hexahedral. But I get this error message: No mesh on domains 1 2 3 in geometry 1, mesh case 0. Could you please help me? Maybe the whole model is wrong but I don't know how it has to be.
Regards,
Jessy
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temporal and spatial discretization
The below post is related to an archived discussion
[start here] Is documentation is required in research corresponding to "temporal and spatial discretization" in FEM
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Modelling 'Helix' Turbine- Meshing Problems
Hi All,
I'm trying to model an alternative type of turbine, which is a version of vertical axis turbine that is deployed horizontally in a micro hydro electric power setting.
I'm relatively new to COMSOL, but I think I've created an accurate geometry model for the turbine. However, when I try to mesh the geometry, I'm getting numerous errors around edges being to small to compared to the element size. I've tried to mesh on the smallest size, but I still have the issue.
I believe the issue comes from the fact that the blades slightly overlap their casing (Turbine rotates with casing, not on a central axis), however this is key for providing a flush finish. I attempted to use a union to remove the interior boundries, between the overlapping blades and the casing. This works at one end of the turbine, however, at the opposite end the interior boundries aren't removed and I believe this is causing issues???
I've also tried changing the mesh manually, but I'm still getting the same issues.
Any meshing tips would be greatly appreciated!
Also my final goal is to calculate the torque of the turbine, and my current calculate is to perform a surface intergration with the expression:
p(nyx-(y+0.2)*nx)
I'm also just using the turbulent flow physics package. If anyone can let me know if im on the right lines, or if I should be using a different physics package to find the torque from the flow please let me know!
Sorry for the questions!
Tom
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Errors of singularities on meshing after integrating the derivative of the solution
Hi,
We are calculating the optical force within metal scatterers in a PEC bounded structure 2D model. The model is bounded by PEC with PMLs on the left and right sides. We define the background field Eb = E0exp(-jk*x) in the y direction and solve for the scattered fields (Please see the attached mph file).
The problem here is that the size of the mesh element can have significant impact on the integral of the force density. Please see the attached jpeg file. The x-axis indicates the maximum mesh element size in the model, which is the wavelength (633nm) over a number # (You may change the parameter, mesh_d, in the mph to have the same figure). The surface integral 1 calculates the gradient term (integral of the derivative of the solutions) and the surface integral 2 gives the Poynting term. The total is equal to the sum of the gradient and Poynting terms. We can see that the gradient term switches from negative value to positive value when varying the maximum meshing size.
https://www.comsol.com/blogs/how-identify-resolve-singularities-model-meshing/
This article explains that some issues may happen when singularities exist. In the conclusion, point 3 says that it is acceptable when calculating the integral of some quantity including the derivative of the solutions. However, we still have significant errors when applying different meshing. We also removed the sharp corners by filleting the scatterers, but the problem remains, especially for the gradient term.
Do you have any solutions toward this issue? Thanks.
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How to prescribe 2D deformation
Hi all,
I would like to study aquatic propulsion using 2D simulation. However, I get stuck in the first step: how to prescribe the model deformation?
I can find the example "The Virtual Aquarium: Simulations of Fish Swimming". However, things are a little bit different in my case. I would like to define the model deformation directly, instead of defining stress to bend the model.
Is there any method that I can prescribe the locomotion of the mesh vertex, therefore, to control the deformation of the model?
Thanks in advance!
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Swept Linking Face Problem Solutions
I am currently having issues linking source faces to its destination face in the swept mesh. The Geometry I am using has a thin device design, and have successfully meshed the source face. When doing the sweep, a side face is currently sounding off an "Unsupported topology of linking face" error even though it is a simple extrude.
I am unsure how to debug this current issue to remove the problem as the geometry is a flat face that should have no topological complexity. The file size is larger than 5 MB and even through optimization I cannot attach it.
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Meshing profile 2D
Hi,
I am working on a 2D wing simulation. I drew a convexe profile and I want to mesh it before computing a tuburlent flow SST phyisic. I have troubles with my solutions convergence and I think it is because of my mesh. I followed the tutorial "flow around an inclined NACA" but I need a more precise mesh for my profile. I tried to make it finer but it didn't work. That is why I want to sudivide my profil to make different domains (by adding points ?) like in the attached file.
Do you think it will resolve my problem ? How can I do such sbidivisions along my profil ?
Thank you,
Best regards,
Julien
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Creating limited contact geometry
I am currently working on simulating conduction within a small packed bed of uniformly sized spheres but having problems with building the geometry and meshing. If I try to form a union, some of the domains become unselectable. And while the alternitive option of forming an assembly doesn't have this problem, it introduces other issues and still refuses to mesh. The file I have attached is has 11 of the 60 spheres I use in my model enabled. 2 of these 11 spheres refuse to be selected if Form Union is used, and show weird things between them in the case of Form an Assembly. The goal is to be able to implement thermal contact BC's at the faces of contacts and either insulated/diffuse surface BC pretty much every where else. Preferably without haveing to manually use the GUI to go through and specify each of the 240+ contact locations manually. Ivar, if you can hear me, I am fully willing to sacrifice an undergrad from our lab upon an alter to you in exchange for your help.
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