Latest Discussions - COMSOL Forums Most recent forum discussions Fri, 07 May 2021 22:41:53 +0000 COMSOL Forum: Latest Discussions Comsol Logical Arguments <p>The below post is related to an <a href="//">archived discussion</a></p> <hr /> <p>I am building a simulation for deep penetration laser welding. However, I cannot use phase-change tools as it is not available on my student license. Keyholing (the process by which a laser penetrates significantly deeper into a material than expected) occurs when the metal at the center of a beam vaporizes and allows the beam to penetrate deeper into the sheet of metal. My goal is to have the heat source to become active at the maximum z-height such that the temperature at this point is less than the boiling point of the material.</p> <p>Is it possible to use a logical formula along the lines of Max(z|T(z)&lt;T_Boiling)? (Read as: The maximum of the set of z values such that the temperature at z is less than the boiling point).</p> Fri, 07 May 2021 22:41:53 +0000 4.2021-05-07 22:41:53.288592 Nonlinear conductivity <p>The below post is related to an <a href="//">archived discussion</a></p> <hr /> <p>Is it possible define lon linear conductivity (sigma(J)) in electrical current modulus? I tryed direct definition of sigma(J) but the program does not recognise J or Jc or Je or normJ neither Jx or Jy that actualy are recognised when solving a linear problem. I am trying to solve a 3D ec problem .</p> <p>Thanks</p> Fri, 07 May 2021 17:53:40 +0000 4.2021-05-07 17:53:40.288591 Complex number of eigenvalue frequency? <p>I have a question about eigenvalue frequency:</p> <p>My material has no damping properties ,Why do my eigenvalue frequency calculations result in complex numbers. (The complex number represents the existence of damping)</p> Fri, 07 May 2021 02:29:21 +0000 4.2021-05-07 02:29:21.288463 Undefined variable problem <p>Trying to do a 3d frequency domain simulation, but it keeps showing this error message:</p> <p>Undefined variable. - Variable: comp1.tEx_lm - Geometry: geom1 - Boundaries: 2, 31 Failed to evaluate Jacobian of expression. - Expression: -comp1.tEx_lm Failed to evaluate Jacobian of expression. - Expression: ((comp1.tEx-comp1.ewfd.PortConstrx)<em>test(-comp1.tEx_lm))</em>(dvol_spatial)</p> <p>I think tEx_lm is Lagrange multiplier for electric field, though I have no idea how to fix it.</p> Thu, 06 May 2021 23:39:49 +0000 4.2021-05-06 23:39:49.288452 AC/DC Module, Surface current density, Layer thickness of Nanoparticles on Polymer <p>Hello,</p> <p>I am trying to build a model of nanoparticles in a polymer. The object is to evaluate the Terminal current and surface current density accross the polymer. One example from the blog, "MAxwell-wagner-Permittivity of Blood" was really helpful. However, unlike their model, my model does not have an intermediate layer between the nanoparticle and the matrix. The model is as below image.</p> <p>[Image]</p> <p>My questions are as follows -- <em>1. Do I need to put a contact impedence BC for the surface of the nanoparticles?</em> <em>2. If yes, what "Surface thickness (Thin layer)" or "Surface impedance" properties should I use?</em> Note: I am only putting nanoparticles (Such as - TiO2) in polymer (such as - PMMA).</p> <p>The terminal current is almost the same if I use or do not use the Contact impedence condition, but the surface current density is completey different!</p> <p><img src="http://" alt="" /> Thank you.</p> <p>Best, Didar</p> Thu, 06 May 2021 21:55:42 +0000 4.2021-05-06 21:55:42.288442 Helmholtz with Flow Tutorial Not working at Higher Mach Numbers <p>Hi,</p> <p>I have edited the Helmholtz with Flow Tutorial geometry and used the L-Vel fluids model rather than SST. I would like to model Mach=0.3 flow, but I get the error:</p> <p>There are 11923 degrees of freedom giving NaN/Inf in the vector for the variable comp1.uPlus. at coordinates: (0.265158,0.0136567,0.0745744), (0.265875,0.0149679,0.0745744)...</p> <p>I have checked the boundary conditions, mesh and air properties as suggested in other threads, but I still get an error.</p> <p>Any suggestions would be much appreciated.</p> <p>Thanks</p> Thu, 06 May 2021 13:57:08 +0000 4.2021-05-06 13:57:08.288431 Connecting 2 of the same physics nodes? <p>I've got a large model which can be divided into an FSI section, and a pure fluid flow section.</p> <p>To keep the RAM requirements down, I am trying to use a segregated approach, wherein all of the FSI physics are solved in one step (Laminar 1, Solid Mechanics, FSI), and then the remaining pure flow section (Laminar 2) is solved in a second step.</p> <p>I have been able to do things like using 2 different order Solid Mechanics nodes (Quad for beams, Linear for a big paddle), and can get them to work together by naming the dependent variables the same in both nodes. (u_solid in both) And some luck using multiple components to transfer fluid velocity using a nojac(genext&lt;...>) command in the inlet to the non-FSI component, but I am not sure if that is one way coupling, like a simple open boundary for the FSI side.</p> <p>Anyone have some prior experience with things like this? The end goal is to have a large (like 5-7M equation) model of a MEMS instrument, which will have a supporting FSI section, a solid mechanics/electrical driving section, and a second smaller FSI section near the driver, where the driving section's solid mechanics are linked to the supporting FSI section's solid mechanics... So a very large problem and resulting matrix.</p> <p>The approach I am trying to implement is to break the model up into the 3 sections described above, either into discrete components that are solved in an internally-fully-coupled manner, in a larger segregated solver loop, or by having one model where different physics nodes are assigned to the different sections, and are somehow linked together. Is this doable in Comsol? Should this be done as a union with many physics nodes, an assembly with many nodes, or components with extrusion coupling?</p> <p>Thank you in advance, I know this is a rather loaded and detailed question.</p> Thu, 06 May 2021 12:29:21 +0000 4.2021-05-06 12:29:21.288422 The function emw.S1x in S-parameter definition; evaluating reflection/transmission on interior geometry <p><strong>Short description:</strong></p> <p>In Equation View I find the following definition of the S11 parameter:</p> <blockquote> <p>emw.S11 = if(abs(emw.beta_1)>1.0E-7 * emw.intport1(emw.k)/emw.Area_1&amp;&amp;(abs(arg(emw.beta_1))&lt;=0.25<em>pi||abs(arg(emw.beta_1))>=0.75</em>pi),emw.S1x * exp(-j*phase),0)</p> </blockquote> <p>I can find all these functions, e.g. emw.beta_1, defined elsewhere in Equation View, but I cant see emw.S1x anywhere. Does anyone know what it is and what expression defines it?</p> <p><strong>Long description and context:</strong></p> <p>I am currently trying to re-write my own S-parameters in order to evaluate transmission and reflection on a surface <em>inside</em> my geometry, in contrast to the normal S-parameters that take readings from the ports that has to be placed on boundaries defining exit/enter locations of the electromagnetic waves.</p> <p>My model is a simple waveguide with two ports on either end, where Port 1 excites the incident wave. I want to measure transmittance and reflectance very close to the center of the waveguide, but still need the ports to be placed sufficiently distanced from each other. So I cannot use e.g. the traditional abs(emw.S11)^2 as it reads the reflectance outside the region of interest.</p> <p>My plan is to define my own variable, say comp1.S11_z0, that does the same as emw.S11 but instead of integrating over the area of Port 1 it integrates over a similar surface placed at z=z0, closer to the center (z=0) of the waveguide. It should also take into account material properties at z0 instead of at wherever Port 1 is. I attached an image of the waveguide. Marked are Port 1 and the surface closer to center. Unmarked are Port 2 and its corresponding surface.</p> <p>In Equation View I find the following definition of the S11 parameter:</p> <blockquote> <p>emw.S11 = if(abs(emw.beta_1)>1.0E-7 * emw.intport1(emw.k)/emw.Area_1&amp;&amp;(abs(arg(emw.beta_1))&lt;=0.25<em>pi||abs(arg(emw.beta_1))>=0.75</em>pi),emw.S1x * exp(-j*phase),0)</p> </blockquote> <p>I have written new variants of emw.beta_1, emw.k, emw.Area_1, emw.intport1() and their subsequent function emw.alphaport_1 to fit this new S11_z0, but I need to rewrite emw.S1x to complete the expression. I don't know what emw.S1x is and cannot find its definition anywhere. Anyone able to help out?</p> <p>On a final note, I bet there is a simpler way to read reflection/transmission power on interior geometry. I am open for suggestions for other methods!</p> Thu, 06 May 2021 09:56:45 +0000 4.2021-05-06 09:56:45.288411 Fokker-Planck equation <p>Can someone show me how to simulate the Fokker-planck equation (see attachment) in COMSOL:</p> <p><img class="latexImg" src="data:image/png;base64,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" /></p> Thu, 06 May 2021 08:17:37 +0000 4.2021-05-06 08:17:37.288401 How to extrude an imported 2D .dxf file in COMSOL <p>Hello Everyone,</p> <p>I have a generated 2d image which is converted to dxf file. It can be easily imported and recognizied all the edges and points. But I like to convert to 3d by extruding it. Is there any way to convert it to cylindrical cross section and rectangular cross section. I have attached the model. Any help please? Thank you!</p> Wed, 05 May 2021 21:07:14 +0000 4.2021-05-05 21:07:14.288382 FSI: Moving mesh (ale) vs Moving mesh <p>Hello,</p> <p>I have the doubt of which of these two options select for my FSI simulation:</p> <p>-The moving mesh in: Components-Definitions-Moving mesh-Deforming Domain</p> <p>-The moving mesh (ale) in: Components-Moving mesh</p> <p>If I use moving mesh (ale) in the results I can only see the deformation of the boundary separating the fluid from the solid, while if I use moving mesh I can see the meshes deforming properly not only in the boundary. Is there any difference between the two? Does it impact only to the visualization?</p> <p>Thank you</p> Wed, 05 May 2021 20:45:36 +0000 4.2021-05-05 20:45:36.288381 Geometry position setting(emergency help) <p>Dear reader, There have an emergency ,I imported a 2D geometry file from DXF to comsol, but how to set the position of this 2D geometry freely(that means x and y axis coordinates)?</p> <p>I think that may be a simple setup, does there anyone have any good suggestions? Thany you so much!</p> Wed, 05 May 2021 20:03:53 +0000 4.2021-05-05 20:03:53.288371 Relating Material Property to Coordinate <p>Hello, I am trying to analyze a leaf venation structure using COMSOL to find the maximum deflection of a leaf due to gravity acting on the surface. I am using the structural mechanics module with a beam and shell couple. I have modeled the leaf's veins as beams and the leaf's skin as a shell in my COMSOL file. I drew the geometry of the leaf in AutoCAD and imported it to COMSOL. Each vein of the leaf system has a different radius, but in my geometry I drew all the beams as just 2D lines without a radius. I am wanting to correct analyze this system by incorporating each vein's radius which I have data for in an Excel file. To do this I need to determine each beam's unique ID from COMSOL in order to write .txt file relating the geometry from my COMSOL file to each corresponding radius I have in my data sheet. Is there a way to export the geometry of each beam from my COMSOL file so I have each unique ID in my COMSOL geometry? Or, is there a way to create a function for the material properties for density relating the coordinates of each beam and their respectful radii? Any help would be appreciated. To summarize: I am trying to analyze a large leaf venation system with various radii. Each vein has a different radius but I have not drawn this in the geometry for my structure. If I want to relate the density of my leaf beams to their respectful radii how can I go about this with the coordinates and/or ID's of each beam?</p> <p>I am attaching the Leaf COMSOL file to this post. Thank you</p> Wed, 05 May 2021 19:45:06 +0000 4.2021-05-05 19:45:06.288362 How to add all overpotentials in SOFC unit cell <p>Hello , i am facing a difficulty in adding overpotentials in my sofc model. The activation overpotential , concentration overpotential and ohmic overpotential are three losses in overall voltage of sofc during load conditions . i have slight understanding of all these overpotentials but i am unable to model it in concentration overpotential is related to partial pressures of spcies at bulk and reaction sites , and when i declare a variable at different domains it shows error .</p> <p>Regards</p> Wed, 05 May 2021 15:17:58 +0000 4.2021-05-05 15:17:58.288341 How to calculate the current density in 3D lithium battery? <p>Dear professor, I am doing a modeling about lithium ions battery,3D,in the case library "Heterogeneous Lithium-Ion Battery", a current density is applied to the current collector but don't say the formula to calculate it. I have read some papers the formula have diffent expression so i want to ask can anyone know how to calculate it and tell me the formula to calculate it? The model i give a photo below.</p> Wed, 05 May 2021 14:20:24 +0000 4.2021-05-05 14:20:24.288333 Error message while simulating cooling of electronic chip <p>I am new to COMSOL and Heat transfer physics. I created an Air Box for cooling my antenna system and electronic chip, where the fluid is Air (Laminar flow) with mean inlet velocity to be 0.1m/s. (No slip boundary condition along the walls) (Used NON-Isothermal flow multiphysics coupling laminar and heat transfer in solids and fluids). I wanted to make a parametric analysis by changing this inlet velocity and observe the temperature difference.</p> <p>However except for 0.1 m/s velocity I am receiving the following error for other inlet velocity. I am not sure what this means and what I need to change?. It would be great if someone can help me with this</p> <p>Undefined value found. - Detail: Undefined value found in the equation residual vector. There are 12401 degrees of freedom giving NaN/Inf in the vector for the variable comp1.T. at coordinates: (-0.00312885,-0.00348848,0.000750958), (-0.00329311,-0.00347151,0.000602882), (-0.00313693,-0.00348252,0.000893459), (-0.0028697,-0.00341622,0.00103094), (-0.00329131,-0.00345004,0.000470919), ... There are 5991 degrees of freedom giving NaN/Inf in the vector for the variable comp1.p. at coordinates: (-0.00312885,-0.00348848,0.000750958), (-0.00314467,-0.00345428,0.000460907), (-0.00320986,-0.00358701,0.000656224), (-0.00313693,-0.00348252,0.000893459), (-0.00300292,-0.0034142,0.000919043), ... There are 12345 degrees of freedom giving NaN/Inf in the vector for the variable comp1.u. at coordinates: (-0.00312885,-0.00348848,0.000750958), (-0.00329311,-0.00347151,0.000602882), (-0.00313693,-0.00348252,0.000893459), (-0.0028697,-0.00341622,0.00103094), (-0.00329131,-0.00345004,0.000470919), ... There are 12345 degrees of freedom giving NaN/Inf in the vector for the variable comp1.v. at coordinates: (-0.00312885,-0.00348848,0.000750958), (-0.00329311,-0.00347151,0.000602882), (-0.00313693,-0.00348252,0.000893459), (-0.0028697,-0.00341622,0.00103094), (-0.00329131,-0.00345004,0.000470919), ... There are 12345 degrees of freedom giving NaN/Inf in the vector for the variable comp1.w. at coordinates: (-0.00312885,-0.00348848,0.000750958), (-0.00329311,-0.00347151,0.000602882), (-0.00313693,-0.00348252,0.000893459), (-0.0028697,-0.00341622,0.00103094), (-0.00329131,-0.00345004,0.000470919), .</p> Wed, 05 May 2021 13:18:00 +0000 4.2021-05-05 13:18:00.288331 Magnetic force on a deforming domain <p>Hello,</p> <p>I am trying to simulate a resonator which is subject to both applied external force and a magnetic force in 3D. The applied external force is defined, while the magnetic force needs to be computed, using Maxwell stress tensor, at each position of the resonator in space. I want to compute the device displacement using a time dependend study. At each time step I would like to compute the displacement of the resonator due to both external and magnetic force and update the magnetic force for the following step given the new position of the resonator.</p> <p>I have tried to use a time-dependent study with both solid mechanics and magnetic field no currents. They both converge if only one physics is used, but they fail to converge when used together. I imagine that I should use moving mesh at each step to update the position of the resonator in space and compute the new magnetic field and maxwell stress tensor. The problem is that solid mechanics says that it cannot be used on deforming domains.</p> <p>Any idea?</p> <p>Thank you</p> Wed, 05 May 2021 12:41:59 +0000 4.2021-05-05 12:41:59.288321 LES CHANNEL395 <p>Dear Bloggers and COMSOL Community member, do anyone have a case setup of LESchannel 395 case?</p> Wed, 05 May 2021 09:23:31 +0000 4.2021-05-05 09:23:31.288311 Axisymmetric Integration is giving wrong results <p>Hello guys</p> <p>I ran into an issue while computing an integral (intop1) in an axisymmetric simulation, I have a variable which is pressure (p) and I need to integrate it over a body surface, when integral is calculated it's yielding force in r-direction which is not correct at all. does anyone have any idea why this happens? is it a bug?</p> <p>Best, William</p> Wed, 05 May 2021 08:55:26 +0000 4.2021-05-05 08:55:26.288302 when we do the tensile stress simulation, why we have to select the materials and power? <p>In recent days, I saw many videos about comsol tensile simulation.</p> <p>All the people applied specific power and materials to their structure.</p> <p>So I followed it and I get the result below.</p> <p>But, when I changed the material or tensile power, all the results showing the same result.</p> <p>(It only shows the distribution of the stress.)</p> <p>So, why people select the material and power?</p> Tue, 04 May 2021 07:32:54 +0000 4.2021-05-04 07:32:54.288251