Latest Discussions - COMSOL Forums Most recent forum discussions Wed, 17 Jul 2019 11:29:14 +0000 COMSOL Forum: Latest Discussions Implementation of Preisach Hysteresis Model <p>Hi, I have implemented the model of a common mode choke for electrical drives, now I have to calculate the magnetic losses of the ferromagnetic core. In order to do this and to make the hysteresis curve BH, I would use the Preisach Model. Someone could give me directions point by point on how to do it. Thanks a lot</p> Wed, 17 Jul 2019 11:29:14 +0000 4.2019-07-17 11:29:14.239291 Surface plot of velocity in Comsol for a 2D flow case <p>If I want to plot surface velocity profile in Comsol such that we have a plane on horizontal surface and variation of velocity is shown in vertical direction as if it appears to be a truncation, how to do that? I am attaching a similar figure of what I need to draw. If anyone has any idea regarding this, kindly help. Thanks.!</p> Wed, 17 Jul 2019 06:34:24 +0000 4.2019-07-17 06:34:24.239271 How to download the software--comsol multiphysics? <p>Hello,can you help me to find the way about downloading it?I can't find corresponding download link.I want to study it in some experiments as a college student.Thank you.</p> Wed, 17 Jul 2019 03:26:34 +0000 4.2019-07-17 03:26:34.239263 why partial derivative of the hydrostatic pressure field equals to 0? <p>Excuse me, I solved the two-dimensional hydrostatic pressure field solid.p. The hydrostatic pressure solid.p distribution is not uniform. Use d(solid.p, x) to solve the partial derivative of solid.p along the x direction. Why is the calculation result 0?</p> Wed, 17 Jul 2019 01:31:40 +0000 4.2019-07-17 01:31:40.239213 Heat profile used in different model <p>Hello, I am pretty new at comsol, I have simulated joule heating physics and achived heat profile across my design. Now I wish to simulate stress induced by heat in the same model. The problem with simulation is that I am unable to work with identity pair in solid mechnics and I am using identity pairs joule heating simulation. I tried changing the from identity pair to contact pairs but they won't work(perhaps I don't know how to make them work). So I have decided to use the heat profile achived in the joule heating simulation for solid mechanics. Is there any way to simple import the heat profile or use that temperature to continue with simualtion?</p> Tue, 16 Jul 2019 23:47:38 +0000 4.2019-07-16 23:47:38.239211 How to extract the stiffness matrix and mass matrix of the element in comsol <p>How to extract the stiffness matrix and mass matrix of the element in comsol, I know that the code mphmatrix can extract the global stiffness matrix ,global mass matrix and so on. Yet i want to extract the matrix information of element,but i do not how to extract it? can comsol solve this problem. Or someone can offer me other methods, it is thanksful. If there is no other way, is it only possible to construct a shape function to perform the grouping of the element stiffness matrix.</p> Tue, 16 Jul 2019 23:44:01 +0000 4.2019-07-16 23:44:01.239202 Periodic Boundary condition in a multiphysics. <p>Hello everyone,</p> <p>I am new to COMSOL, and I was in a confusion about the boundary conditions applied to the multiphysics. I am working on a piezoelectric model and want to apply periodic BC to the model. Do I need to apply it from both physics (solid mechanics and electrostatics) or it is fine if I apply it from just solid mechanics. I also want to know about how to apply initial or external strains on points rather than domain.</p> <p>Thanks</p> Tue, 16 Jul 2019 19:24:36 +0000 4.2019-07-16 19:24:36.239182 Balanced and Unbalanced Signals <p>Hello,</p> <p>I would like to study on baluns by using COMSOL. I need to convert between a balanced signal and an unbalanced signal. I had assumed that the coaxial lumped port is unbalanced. But after I did some simple test on the <a href="">Dipole Antenna with a Quarter-Wave Coaxial Balun</a> example, I got confused.</p> <p>The reason of my confusion is that, There is not a real difference between the electric field distribution on the dipole arms when the balun exists and doesn't exist. I attached both images to this discussion.</p> <p>Without a balun, Is it supposed to be left arm is not electrified since it is connected to outer metallic shield?</p> Tue, 16 Jul 2019 15:28:39 +0000 4.2019-07-16 15:28:39.239181 Problem in the creeping flow model: does not work in one case but works in a very similar case <p>Hi, I'm having a problem with comsol : I do not know if it come from a ill-posed physic or if it's a "numerical problem". Indeed, I use the creeping flow model on a rectangle with an inlet (p = 1) to the right, outlet (p=0) to the left and symmetry up and down. The result is given in the first picture below and it doesn't work. Then I consider the same geometry minus a circle (its center is on the lower border of the rectangle ; see the second attachment below) and with the same boundary condition : here the computation is done by comsol and the result seems consistent (cf. last attachment). I do not understand why it works in one case but not in the other. Do you have any idea where this may come from?</p> Tue, 16 Jul 2019 12:39:35 +0000 4.2019-07-16 12:39:35.239171 Hexagon spiralled channel <p>Hi,</p> <p>I need to model a hexagon spiralled channel in a similar fashion of a circular one, which is taught here:</p> <p>Would anyone have any hints? Thanks in advance!</p> Tue, 16 Jul 2019 12:38:01 +0000 4.2019-07-16 12:38:01.239161 how to know the meaning of phrase like ewfd.nxx or ewfd.kixx used as part of expression for variables <p>Hi, I find many phrases like ewfd.nxx and ewfd.kixx were used as part of expression for variables and it is hard to konw what these mean.Is there any files to search or anyway to know ? Thanks.</p> Tue, 16 Jul 2019 08:49:45 +0000 4.2019-07-16 08:49:45.239153 Opening/Accessing methods saved in the MPH file outside of the Application Builder <p>Hi, we created an App from MPH file under Windows (Application Builder is only available in Windows). This MPH file was then slightly edited under Linux, but the functionality of the App should not be exposed. Afterwards, we open the MPH file under Windows and upon clicking 'Application Builder', we get 'Unexpected error occured' with some error. By clicking second time on 'Application Builder' button, Comsol screen turns completely white and there's no way out of it other than exiting.</p> <p>We're wondering if there's other way to open/access MPH file and its methods in Java/Matlab and debug the error in more detail. Thanks for any insights Peter</p> Tue, 16 Jul 2019 08:29:39 +0000 4.2019-07-16 08:29:39.239151 How to draw an arc with fixed radius and across two points in MATLAB livelink for COMSOL <p>Hi,</p> <p>I am using matlab livelink to draw a geometry. Does anyone know if there any commad to draw an arc with a specific radius and across two points?</p> <p>Thanks!</p> Tue, 16 Jul 2019 08:10:00 +0000 4.2019-07-16 08:10:00.239141 Solid-beam weld joint <p>I screwed up the Comsol versioning on my previous post so I want to ask my question again, in proper context. I use Comsol 5.2a, I have a simple need to weld one end of a beam to a rigid domain. All I want is a way to specify a boundary condition where the location of beam contact on the rigid domain and the angle of beam contact relative to the local surface of the rigid domain do not change, no matter what else is going on in the simulation.</p> Mon, 15 Jul 2019 22:42:43 +0000 4.2019-07-15 22:42:43.239132 Internal error callback <p>Hi there</p> <p>when I run same case 5 times, maybe 3 times of them failed the error was** internal error callback**. It seems that COMSOL is unstable. It's not always worked or failed.</p> <p>Any help will be appreciated.</p> Mon, 15 Jul 2019 16:08:32 +0000 4.2019-07-15 16:08:32.239122 Laser cavitation <p>Hello ereryone, I am leaning the COMSOL to simulate laser cavitation, unfortunatly, I can not simulate the expansion and collase of bubble. Anyone have the related experience of bubble simulation?Or some learning materials or exact tutorials ? Please help me, my god. Best regard.</p> Mon, 15 Jul 2019 14:10:45 +0000 4.2019-07-15 14:10:45.239093 display the graph for a specific volume <p>Hello,</p> <p>I made the mechanical simulation for a large volume (eg. 0&lt;X&lt;760, 0&lt;Y&lt;760, and 0&lt;Z&lt;80). But I want to general a 3D graph to show the mechanical deformation (strain) for a specific volume (e.g. 285&lt;X&lt;380, 285&lt;Y&lt;380, and 0&lt;Z&lt;80). I didn't find a way to do it. Could anyone help me with this? Thanks.</p> <p>Best regards, Ronggang</p> Mon, 15 Jul 2019 12:46:53 +0000 4.2019-07-15 12:46:53.239091 solid mechanics weird results <p>Hi,</p> <p>I am simulating a piezoelectric device. I am experiencing difficulty in understanding the stress result of the structure. The bottom layer has zero displacement boundary condition, however I see a bulge as seen in the image on the bottom layer. Could anyone help me understand what it is?</p> <p>Regards,</p> Mon, 15 Jul 2019 11:14:47 +0000 4.2019-07-15 11:14:47.239081 heat penetration in microwave oven domain through waveguide <p>The below post is related to an <a href="//">archived discussion</a></p> <hr /> <p>[start here]sir, As I am done with modelling for basic model (heating of water), i came across two problem 1. the study part showing no output as heating of water in jar domain(domain 2) . Even whenever i selecting the 'domain of oven'(domain 1) then 'jar containingwater'(domain 2) inside it is automatically selected. So the boundary condition on boundary of jar is automatically selected as perfectly conductor. and when i adding physic of "heat transfer in solid", after selecting the jar as my domain , its selected as thermal insulator on a same boundary of my jar.</p> <ol start="2"> <li>whenever i have been passing energy through waveguide , it is not been able to go into the microwave oven domain. what shold i do to sort out this problem. please guide me as im new learner to comsol. i am attaching my comsol file , please check out where i gone wrong.</li> </ol> Mon, 15 Jul 2019 08:32:27 +0000 4.2019-07-15 08:32:27.239061 How to set up a circularly polarized light source <p>I'm going to set up a circularly polarized light source in the 2-d model. Now I'm using the boundary condition of the port, but I don't know how to set it.So I hope to get your help</p> Mon, 15 Jul 2019 07:01:31 +0000 4.2019-07-15 07:01:31.239023