Latest Discussions - COMSOL Forums https://www.comsol.com/forum/ Most recent forum discussions Sat, 25 Jun 2022 06:05:09 +0000 COMSOL Forum: Latest Discussions https://www.comsol.com/shared/images/logos/comsol_logo.gif https://www.comsol.com/forum/ Point dipole radiation in COMSOL https://www.comsol.com/forum/thread/310021/Point-dipole-radiation-in-COMSOL?last=2022-06-25T06:05:09Z <p>HI, I am studying point dipole radiation. Can you please explain me what are the mathematical formulas COMSOL uses to calculate electric field and elctric power? Please provide me references if you have.</p> Sat, 25 Jun 2022 06:05:09 +0000 4.2022-06-25 06:05:09.310021 Non-fourier heat conduction equation in cylindrical co-ordinates https://www.comsol.com/forum/thread/310011/Non-fourier-heat-conduction-equation-in-cylindrical-co-ordinates?last=2022-06-24T12:45:37Z <p>Hi , I am new to comsol. I want to know how to implement the PDE ****Non-Fourier heat conduction equation in cylindrical coordinates. The equation and boundary conditions are attached below.</p> Fri, 24 Jun 2022 09:20:22 +0000 4.2022-06-24 09:20:22.310011 pext_opt for Axisymmetric and 2D geometries? https://www.comsol.com/forum/thread/310001/pextopt-for-Axisymmetric-and-2D-geometries?last=2022-06-24T18:06:37Z <p>Hi,</p> <p>We now have pext_opt for 3D geometries which is really cool.</p> <p>Will pext_opt be implemented for Axisymmetric and 2D geometries too?</p> Fri, 24 Jun 2022 08:40:47 +0000 4.2022-06-24 08:40:47.310001 Simulating Pump Probe spectra using COMSOL https://www.comsol.com/forum/thread/309991/Simulating-Pump-Probe-spectra-using-COMSOL?last=2022-06-24T02:04:36Z <p>Hi,</p> <p>I want to corroborate an experimental pump probe spectrum using COMSOL. To do that, I need two EM wave sources with different wavelengths. The pump input is pulse wave with sub-pico second time duration and probe is continuous wave. I am using electromagnetic frequency domain. I am wondering</p> <ol> <li>How one can set multiple EMW sources with different wavelength?</li> <li>How to set pulse of gaussian beam incident wave in comsol?</li> </ol> <p>Any tutorial or inputs will be great help.</p> <p>Thank you!!</p> Fri, 24 Jun 2022 02:04:36 +0000 4.2022-06-24 02:04:36.309991 Simulating lensed single-mode fiber using 2D axisymmetric mode https://www.comsol.com/forum/thread/309982/Simulating-lensed-single-mode-fiber-using-2D-axisymmetric-mode?last=2022-06-23T23:20:09Z <p>Hello, I am trying to simulate a lensed SMF fiber (tapered SMF) using the 2D axisymmetric mode. When I try to lanuch the fundamental mode for just the SMF section, the field distribution which I get is wrong, as it appear in the attached pics. I am not sure what I might be doing wrong.</p> Thu, 23 Jun 2022 23:20:09 +0000 4.2022-06-23 23:20:09.309982 Heat flux and moving mesh https://www.comsol.com/forum/thread/309972/Heat-flux-and-moving-mesh?last=2022-06-23T22:37:38Z <p>Hi, I'm trying to compute the heat flux across a boundary on a moving object. When the mesh moves with a fixed velocity, the heat flux measured is very large compared to the static case, but the temperature distribution is the same. How can I get the measured heat fluxes to be in agreement? For the model, the the analytic function describes the deformation of the mesh over time. Charles</p> Thu, 23 Jun 2022 22:37:38 +0000 4.2022-06-23 22:37:38.309972 What's the meaning of Port off in emw module https://www.comsol.com/forum/thread/309971/Whats-the-meaning-of-Port-off-in-emw-module?last=2022-06-25T18:44:02Z <p>If I set two lumped port in an emw module, fix excitation of one port on and another off, so what's the meaning of this off port.</p> <p>Is this port terminated by the refenence impedance or just keep open/short-circuit.</p> Thu, 23 Jun 2022 13:21:58 +0000 4.2022-06-23 13:21:58.309971 Modelling thermal profile of radiating source on soil https://www.comsol.com/forum/thread/309961/Modelling-thermal-profile-of-radiating-source-on-soil?last=2022-06-23T12:50:12Z <p>Hi everyone,</p> <p>I'm new in COMSOL and I have some troubles with simple studies.</p> <p>I want to study the thermal profile of a point radiating source on a soil. The objective is to understand which form the isothermal lines have.</p> <p>I started with creating a 2D rectangular geometry, and then I put a little circle on the upper side of the rectangle. Now, I filled the rectangle (and the circle, is it right?) of a material (soil). At this point I have problems to continue, in particular in the heat transfer module.</p> <p>Can you please help me? Thanks in advance</p> Thu, 23 Jun 2022 12:50:12 +0000 4.2022-06-23 12:50:12.309961 Mechano-sorptive creep for timber https://www.comsol.com/forum/thread/309942/Mechano-sorptive-creep-for-timber?last=2022-06-23T09:06:51Z <p>Hi,</p> <p>I am modelling the mechano-sorptive creep for hardwood. The 3D equation is attached. However, in the creep under Solid Mechanics Physics, it seems we can only model 2D problem. Is there any option we can model 3D creep?</p> <p>Cheers, Frank</p> Thu, 23 Jun 2022 09:06:51 +0000 4.2022-06-23 09:06:51.309942 Problem in creating mesh https://www.comsol.com/forum/thread/309932/Problem-in-creating-mesh?last=2022-06-22T23:56:13Z <p>There are some mesh problem when try to mesh analysis of this large geometry, saying "failed to generate mesh for domain". I tried with "Ignore edges". But the problem still exists. How to solve the problem?</p> Wed, 22 Jun 2022 23:56:13 +0000 4.2022-06-22 23:56:13.309932 semi infinite geometry with a radiating source https://www.comsol.com/forum/thread/309931/semi-infinite-geometry-with-a-radiating-source?last=2022-06-22T21:28:03Z <p>Hi,</p> <p>I'm really new in Comsol. I'd like to verify with Comsol this problem:</p> <p>I have a semi-infinite domain (say a soil) in the xy plane (with y pointing downward, and x as usual). The soil is in contact with the air (for y&lt;0). Anywhere on the soil, I have a radiating source . I suppose that the isothermal surfaces generated by the source are seen, by an observer located at <img class="latexImg" src="data:image/png;base64,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" />, as semi-circles.</p> <p>My professor asks to plot this geometry, and plot the isothermal surfaces to verify the hypothesis.</p> <p>Can anyone guide me?</p> <p>Thanks</p> Wed, 22 Jun 2022 21:28:03 +0000 4.2022-06-22 21:28:03.309931 Composite faces being non applicable when using Partitioning using extended faces https://www.comsol.com/forum/thread/309921/Composite-faces-being-non-applicable-when-using-Partitioning-using-extended-faces?last=2022-06-22T21:04:21Z <p>Hello Everyone. I am trying to build a mesh for a high aspect ratio structure to get more details. To do that, I am using the partitioning tool to make a sweep mesh. however I am not abke to select composite faces which are circular and they show up in the selection list as non-applicable even though I have selected the domain.</p> Wed, 22 Jun 2022 21:04:21 +0000 4.2022-06-22 21:04:21.309921 Tonpilz Piezo Transducer Tutorial - About Far Field Calculation https://www.comsol.com/forum/thread/309911/Tonpilz-Piezo-Transducer-Tutorial---About-Far-Field-Calculation?last=2022-06-22T20:56:31Z <p>Hello everyone,</p> <p>I am studying the examples in the Application Library in order to improve my skills in the field of acoustics. I would like to ask a question about the Tonpilz Piezo Transducer Tutorial.</p> <p>While designing, we activate the "symmetry in the z=0 plane" part in the far-field calculation. (Tonpilz Piezo Transducer Tutorial - 7:09) Is this necessary? If I put a full sphere around the Tonpilz, would I still need to activate it? If I put a full sphere around it and define water, the side surfaces will now be the "acoustic-structure boundary" and it will affect my calculation.</p> <p>However, I couldn't decide which one was the right one while designing. Since I couldn't find any explanation on the subject, I wanted to ask here. I'm looking forward to your feedback.</p> <p>Best Regards, Hakan.</p> Wed, 22 Jun 2022 20:56:31 +0000 4.2022-06-22 20:56:31.309911 Can I simulate CFD without purchasing CFD module? https://www.comsol.com/forum/thread/309892/Can-I-simulate-CFD-without-purchasing-CFD-module?last=2022-06-22T20:49:32Z <p>Hello! I am new to Comsol and currently trying to simulate CFD with Comsol 6.0. More precisely, I need to set up the main tube which has 2 side tubes (one carries oxygen and another does nitrogen) and find a distribution for each substance. To clarify what I'm talking about, I've attached the image of the simualtion that I need to set. Although, I do not have CFD module since my university wants me to try to simulate without buying any module if possible. Therefore, I wanted to know if I can possibly to simulate only with what I have or have to purchase other modules such as CFD or Porous Media Flow module. Also, if I can simulate with what I have now, I'd like to know how. I have also attached the Physics that I have now to show which option I can use. Thank you!</p> Wed, 22 Jun 2022 18:59:15 +0000 4.2022-06-22 18:59:15.309892 capacitance of parallel plate capacitors https://www.comsol.com/forum/thread/309891/capacitance-of-parallel-plate-capacitors?last=2022-06-22T17:47:19Z <p>Hi, I'm new to Comsol. I want to calculate the capacitance of parallel plate capacitors. Here are the steps.</p> <ul> <li>set two blocks with distance.</li> <li>set a sphere to surround the blocks.</li> <li>use Difference to subtract blocks from the sphere.</li> <li>set the blocks to be silicon and sphere to be air.</li> <li>set one block to be terminal 1 with 1V, another is ground.</li> <li>use Stationary Study to compute. so far, everything is fine. But when i try to sweep the distance between two plates, the capacitance does'nt change. Can somebody help me to find the problem?</li> </ul> Wed, 22 Jun 2022 17:47:19 +0000 4.2022-06-22 17:47:19.309891 Wide Band Gap Semiconductor using Gallium Oxide, Gallium Nitride, AlGaN https://www.comsol.com/forum/thread/309861/Wide-Band-Gap-Semiconductor-using-Gallium-Oxide-Gallium-Nitride-AlGaN?last=2022-06-22T10:13:15Z <p>Has anyone tried simulating wide bang gap material based transistor in COMSOL. I am trying but not being successful.</p> Wed, 22 Jun 2022 10:13:15 +0000 4.2022-06-22 10:13:15.309861 microwave plasma https://www.comsol.com/forum/thread/309853/microwave-plasma?last=2022-06-22T09:07:35Z <p>When I was simulating the microwave plasma dipole microwave plasma source, I changed the frequency in the frequency domain - transient step in the research step and changed 2.45ghz to 6GHz. Under the condition that other operations remained unchanged, the error "repeated error test failed, singularity may occur" was displayed.</p> Wed, 22 Jun 2022 09:07:35 +0000 4.2022-06-22 09:07:35.309853 Compute average distance from heating surface to isotemp surface? https://www.comsol.com/forum/thread/309852/Compute-average-distance-from-heating-surface-to-isotemp-surface?last=2022-06-21T21:18:43Z <p>Hello I am wondering how I can compute an average (volume average) distance from the surface of a heated object (thin wire) to an iso-temperature surface inside the heated medium (medium surrounding the thin wire). See attached png for the model and isotemp surface.</p> <p>I tried to compute either a temperature isosurface or a boolean expression (such as T==295K) and use the extrusion operator to compute distance (as per <a href="https://www.comsol.com/blogs/how-to-compute-distances-between-objects-in-comsol-multiphysics/">this blog post</a>), but when I take the volume average I obtain NaNs as the result. Not sure how to do this correctly, although I feel like it should be fairly simple.</p> Tue, 21 Jun 2022 19:57:20 +0000 4.2022-06-21 19:57:20.309852 Band calculations for TE mode of a photonic crystal slab (3D model) https://www.comsol.com/forum/thread/309851/Band-calculations-for-TE-mode-of-a-photonic-crystal-slab-3D-model?last=2022-06-21T14:37:50Z <p>Hello. I am using <em>Wave Optics</em> module in COMSOL (ver 6.0).</p> <p>When I calculate eigenfrequencies for a 3D model of a photonic crystal slab with the <em>Electromagnetic Waves, Frequency Domain</em> interface, I get the band structure for the TM (normal to slab) mode, but I do not know how to calculate it for the TE (parallel to slab) mode.</p> <p>I think I need to set up a port, but I am not sure how to do it. Could you please give me information on that?</p> <p>Thank you.</p> Tue, 21 Jun 2022 14:37:50 +0000 4.2022-06-21 14:37:50.309851 How to establish Helix spring with wanted cross section and add some sub-sturctures on it? https://www.comsol.com/forum/thread/309843/How-to-establish-Helix-spring-with-wanted-cross-section-and-add-some-sub-sturctures-on-it?last=2022-06-22T14:05:12Z <p>Hello</p> <p>I want to make a simulation with helix structures with specific cross section? How to do it?Could you give me some suggestions about it?</p> <p>In addition, I also want to place some sub-structures on the pitch of helix. How to realize it?</p> <p>Thanks</p> Tue, 21 Jun 2022 11:39:06 +0000 4.2022-06-21 11:39:06.309843