Latest Discussions - COMSOL Forums https://www.comsol.com/forum/ Most recent forum discussions Thu, 21 Nov 2019 03:32:11 +0000 COMSOL Forum: Latest Discussions https://www.comsol.com/shared/images/logos/comsol_logo.gif https://www.comsol.com/forum/ how to set up a Semi-infinite area https://www.comsol.com/forum/thread/246833/how-to-set-up-a-semi-infinite-area?last=2019-11-21T03:32:11Z <p>I want to build a semi-infinite area. how to setup the periodic boundary condition</p> Thu, 21 Nov 2019 03:32:11 +0000 4.2019-11-21 03:32:11.246833 How do you plot a Temperature graph along this line? https://www.comsol.com/forum/thread/246821/how-do-you-plot-a-temperature-graph-along-this-line?last=2019-11-20T19:55:18Z <p>I have a 3D reactor model with baffles, and I want to plot the temperature and concentration of the average velocity path (line shown on the surface of the reactor).</p> <p>Need a way to determine the temperature or concentration along the line or at certain points of the line.</p> Wed, 20 Nov 2019 19:55:18 +0000 4.2019-11-20 19:55:18.246821 Simulating flow through a branched pipe https://www.comsol.com/forum/thread/246811/simulating-flow-through-a-branched-pipe?last=2019-11-21T04:49:32Z <p>I am new to COMSOL. I am looking for a tool that can simulate flow through branched pipe.</p> <p>I'd like to know if it is possible to simulate 1D solute transport in a pipe section that diverges into 2 sections and converges again .</p> Wed, 20 Nov 2019 17:47:36 +0000 4.2019-11-20 17:47:36.246811 plot Dean flow vortex https://www.comsol.com/forum/thread/246802/plot-dean-flow-vortex?last=2019-11-20T16:39:07Z <p>I simulated the flow in a curved channel, and want to see the streamline in the cross section. I defined the cut plane, and since the curve is some sort parameterive curve, I didn't know how to calculate the projected velocity on the x and y axices of the cut plane.</p> Wed, 20 Nov 2019 16:39:07 +0000 4.2019-11-20 16:39:07.246802 Acoustic / Ultrasonic related queries https://www.comsol.com/forum/thread/246801/acoustic-ultrasonic-related-queries?last=2019-11-20T16:35:43Z <p>Hi,</p> <p>can any one suggest me, how to develop wave equation in comsol model.?</p> <p>A wairing your reply.</p> <p>Regards,</p> <p>Vipul</p> Wed, 20 Nov 2019 16:35:43 +0000 4.2019-11-20 16:35:43.246801 How to find the temperature of meniscus during capillary filling https://www.comsol.com/forum/thread/246792/how-to-find-the-temperature-of-meniscus-during-capillary-filling?last=2019-11-20T08:15:28Z <p>Hello,            I am trying to simulate 3d rectangular capillary filling using Leve set and two-phase flow, but simultaneously heat or (put at T+Tref) the one wall of the capillary, everything including (meniscus position(ls.Vf1), velocity, etc.) I found easily. The problem is, I am not able to calculate/plot the temperature profile along with the meniscus at some instant (look at attached figure). Thanks in advance!</p> Wed, 20 Nov 2019 13:12:56 +0000 4.2019-11-20 13:12:56.246792 Use interior fan to resemble submersible mixer https://www.comsol.com/forum/thread/246791/use-interior-fan-to-resemble-submersible-mixer?last=2019-11-20T08:12:48Z <p>I am trying to make a 2D model of a reservoir filled with liquid, with submersible mixers in it. In 2D, the only option I see is to use the interior fan, but I am uncertain what values I should use as input for the static pressure at no flow and the free delivery flow rate. I know the stationary power of the motor, the stationary RPM and the diameter of the propeller. Can anyone advise me on how I would translate these known values to the ones asked for the interior fan?</p> <p>Thanks in advance!</p> Wed, 20 Nov 2019 08:12:48 +0000 4.2019-11-20 08:12:48.246791 How to set the Values of dependent variables https://www.comsol.com/forum/thread/246783/how-to-set-the-values-of-dependent-variables?last=2019-11-20T07:13:08Z <p>I want to solve a pair of equations which are based on other two study steps, but in the setting of the "values of variables not solved for", I can only choose on study( and i actuallly want to add two study). How do I pass the solved value of the varibles into the equations that I try to solve subsequently? <img src="http://" alt="" /> For example, I first solve a pair of question to get the Value of U and V, then I solve another equation to get the value of p, the finally I want to solve w and k, whose equations involve with U, V and p. How should I pass the value of U, V and p.</p> Wed, 20 Nov 2019 07:12:39 +0000 4.2019-11-20 07:12:39.246783 Mobility analysis in electron beam interaction https://www.comsol.com/forum/thread/246761/mobility-analysis-in-electron-beam-interaction?last=2019-11-20T04:09:22Z <p>Hi everyone, I am trying to simulate a model to calculate the mobility of the charge carriers in a semiconductor on which some potential is applied and it interacts with a beam of incoming electrons and photons. How to proceed for this? I am new to COMSOL. Any leads will be highly appreciated.</p> Wed, 20 Nov 2019 04:08:29 +0000 4.2019-11-20 04:08:29.246761 How to apply comsol moving mesh in weak form pdes application mode? https://www.comsol.com/forum/thread/246741/how-to-apply-comsol-moving-mesh-in-weak-form-pdes-application-mode?last=2019-11-20T01:35:56Z <p>Hi,</p> <p>I am simulating a bubble moving in fluid using Weak form PDEs application mode. I am applying moving mesh capability. The problem is, my mesh moves but the bubble do not move. Please can someone upload an mph file where moving mesh capability is utalized with weak from PDEs?. I cannot upload my file because the space is not enough.</p> Wed, 20 Nov 2019 01:35:56 +0000 4.2019-11-20 01:35:56.246741 2DEG In COMSOL https://www.comsol.com/forum/thread/246732/2deg-in-comsol?last=2019-11-20T08:41:54Z <p>If anyone could share their insight on acheiving the 2DEG in a HEMT in COMSOL, I would be grateful.</p> Tue, 19 Nov 2019 23:46:33 +0000 4.2019-11-19 23:46:33.246732 solid.pw https://www.comsol.com/forum/thread/246721/solid-pw?last=2019-11-20T14:18:47Z <p>Hi all,</p> <p>I have some doubts regarding the variable solid.pw ; In particular, which is its meaning and which is the difference between solid.pw and solid.pm?</p> <p>Thanks a lot, Maria</p> Tue, 19 Nov 2019 22:06:27 +0000 4.2019-11-19 22:06:27.246721 Additive Manufacturing model - requesting feedback https://www.comsol.com/forum/thread/246711/additive-manufacturing-model-requesting-feedback?last=2019-11-20T14:44:27Z <p>Hello fellow Comsol users,</p> <p>I am currently working on a layer-by-layer thermal simulation for additive manufacturing and by now, my results are not bad, though still far from perfect. In order to further improve the current model, I'd love to hear your feedback and maybe a few tips.</p> <p>The meshing is a topic I'm most uncertain about right now, since I feel there's the highest potential for optimization.</p> <p>Feel free to take a look. Also attached is experimental data as well as a version of my current simulation model. I solved a problem earlier where the first layers temperature spike was much too high. As you can see, I still have a slight problem with high temperatures. Any ideas why?</p> Tue, 19 Nov 2019 17:53:59 +0000 4.2019-11-19 17:53:59.246711 Change the label of reference system https://www.comsol.com/forum/thread/246701/change-the-label-of-reference-system?last=2019-11-19T16:11:06Z <p>Hi, is it possible to change the default label of the reference system {x, y, z} in a different triplet named {1, 2, 3}? It is just a matter of graphics especially when exporting an image of the model. Thanks in advanced, Regards.</p> Tue, 19 Nov 2019 16:11:06 +0000 4.2019-11-19 16:11:06.246701 Simulating a half filled eppendorf tube in a centrifuge https://www.comsol.com/forum/thread/246681/simulating-a-half-filled-eppendorf-tube-in-a-centrifuge?last=2019-11-19T14:07:09Z <p>Dear all,</p> <p>We try to model the flows in an eppendorf tube while it's rotating in a centrifuge (positioned under an angle).</p> <p>We where succesfull in simulating a fully filled tube using the rotating machinary module in 3D. Now we want to expand the simulations to also include half filled tubes (water at the bottom and air at the top). Unfortunatly we find that the rotating machinary module only offers mixture models for multiphase flow.</p> <p>Has anybody a good suggestion on which modules or combination of modules is best used to tackle this kind of problem ?</p> <p>With Kind Regards Sander Stroobants and colleagues.</p> Tue, 19 Nov 2019 14:07:09 +0000 4.2019-11-19 14:07:09.246681 Explanation for the irregularity in my model https://www.comsol.com/forum/thread/246642/explanation-for-the-irregularity-in-my-model?last=2019-11-19T06:01:46Z <p>Hello, I made a 2D model for a single slit diffraction using EM waves and frequency domain. There seems to be some irregularity in the planar wave before the slit. Is this due to some reflection that I am not aware of or is it interference from the many source points along the bottom boundary?</p> <p>https://www.youtube.com/watch?v=XnT45kzu53c This is the video I was basing my work off of and they seem to have a similar problem.</p> Tue, 19 Nov 2019 06:01:46 +0000 4.2019-11-19 06:01:46.246642 About Langmuir probe in comsol https://www.comsol.com/forum/thread/246633/about-langmuir-probe-in-comsol?last=2019-11-19T07:39:05Z <pre><code>Hello,everyone! I have a question in my thesis topic.I wonder if the Langmuir probe can work in the established comsol model, and if so, is it possible to define the probe portion directly in the established model? I'm so confused and try to find some useful articles,but not.Please reply me if you have any ideas.Thank you very much. </code></pre> Tue, 19 Nov 2019 03:28:52 +0000 4.2019-11-19 03:28:52.246633 general stress-strain relation for fluid https://www.comsol.com/forum/thread/246632/general-stress-strain-relation-for-fluid?last=2019-11-19T00:23:57Z <p>Is it possible to define a general stress-strain relation for non-Newtonian laminar flow? Laminar flow seems to require you to define a dynamic viscosity. However I am trying to implement a flow law with a complicated stress-strain relation that does not yield a simple analytical equation for viscosity (see attached). Is it possible to define fluid properties more generally (other than externally solving for viscosity as a function of strain rate and then inputting an interpolation function for the viscosity)?</p> Tue, 19 Nov 2019 00:23:57 +0000 4.2019-11-19 00:23:57.246632 variable names https://www.comsol.com/forum/thread/246622/variable-names?last=2019-11-19T07:34:25Z <p>I would like to define functions for some material properties and need to use variables like shear rate in the function. I found from other posts that, for example, the laminar flow shear rate is spf.sr, but I was wondering if there's a way to find variable names in general either through the interface or documentation?</p> Mon, 18 Nov 2019 23:07:31 +0000 4.2019-11-18 23:07:31.246622 Non-Newtonian Laminar Flow, user defined flow law https://www.comsol.com/forum/thread/246612/non-newtonian-laminar-flow-user-defined-flow-law?last=2019-11-19T21:24:54Z <p>I am trying to model ice (non-Newtonian laminar) flow under martian conditions using a flow law used in the literature for non-terrestrial ice modeling. It is essentially a power law form but combining multiple modes of deformation that use different exponents in the power law. This does not fit into any of the pre-defined models available and it appears that in version 5.5 it is no longer possible to use user-defined functions for flow laws. Am I missing something or do I need to go back to 5.4 to do this?</p> Mon, 18 Nov 2019 22:48:57 +0000 4.2019-11-18 22:48:57.246612