Hello everyone,
I am having a problem getting accurate end results In my solutions. Whenever I Compute my program I just get zeros across the board for all solutions. I keep getting a warning signal saying " low minimum element quality" in my mesh tab. Any help would be highly appreciated, thanks.
Hi, I am a newcomer in comsol. I am doing a cylinder compression test,These are some of the problems I have encountered, and I would be grateful if they were solved.
How to draw a curve between any two quantities in the result using a transient solver in solid mechanics?(for example, how to plot the resultant force on the cylinder surface and the surface pressure displacement under the specified velocity constraints)
The below post is related to an archived discussion
Hello,
I am currently working on the design of a thermal energy storage, and I would like to study convection and conduction in a closed-circuit flow, using an interior fan, but my model does not converge.
The model is described in the picture or in the Comsol file attached.
A double pipe in placed inside a tank. In the inner diameter of the pipe flows hot air with known parameters. In the outer diamater flows water, which enter at the bottom of the tank and exit at the top.
Am I using the interior fan node the wrong way? Do I necessarily need to put an inflow and an outflow node in the water tank part (because I feel like the software doesn't like that the tank where is applied 'turbulent flow' is nearly motionless) ?
Thank you in advance !
Hi everyone,
I am new to Comsol and I am studying the process of drying of a bed of tea leaves, considering them as a porous media. I came across the Comsol model Evaporation in Porous Media with Large Evaporation Rates and blog article How to Model Heat and Moisture Transport in Porous Media with COMSOL®. They both refer to the "evaporation flux" equation which includes the term "evaporation rate". The Comsol model Evaporation in Porous Media with Large Evaporation Rates shows the equation at pag. 5. I also attached a screenshot of the equation below.
Would anyone be able to explain me the term "evaporation rate"?
Thank you, Francesco.
The below post is related to an archived discussion
[start here]
A model that previously worked now reads the error: " Feature: Compile Equations: Time Dependent (sol1/st1) Error in multiphysics compilation. No filename given."
I did not make any changes to file names or settings. Any suggestions?
Thanks.
I have problems creating the electric field of the XLPE cable. I want to know the effect of the electric field stress. And the effect of the XLPE insulated electric field please help me
Hello,
I am analysing the gas flow in coal mass and the resultant deformation of the coal matrix. There, the gas flows through the coal fractures, diffuses through the coal matrix and adsorbed on to the coal matrix, resulting in matrix swelling. I can model the flow in fractures with Darcy flow module, diffusion and adsorption with coefficient form PDE and deformation with solid mechanics module.
I have used contact models to model fracture closure due to matrix swelling. There I need to plot the variation of fracture aperture with time. I noticed that we can do it in COMSOL using 'gap distance', but I could not plot the graph. The geometric model is attached herewith. Could you please explain to me how to plot the distance between two points that are highlighted in the figure? (Which type of graph should I use, which variable, etc.)
Thank you, Suresh.
material used for gate dielectric is silicon dioxide.
Please I need help simulating a suspended microheater, heater - Platinum, Membrane - Silicon Oxide and Silicon Nitride, suspended over Silicon. I have tried the Joule Heating and Thermal expansion Physics, and it came out with a very bad result (Simulating for Temperature, Power consumption and Stress). I'm a new user and i've tried and failed! watched couple of videos but still can't pull through. Please a detailed step by step guide will be appreciated even if it's a link. thanks in anticipation.
Hi all, I am new to COMSOL. I have already performed eigenfrequency analysis of a 2D silicon plate clamped at both ends vibrating in air. I now want to simulate the transient response of the motion by exciting the plate with a ultrasonic source close to the resonant frequency incident on the plate from top (in air). Is there a tutorial for this exercise available? I have doubts on how to correctly defining a sinusoidal excitation, and set the appropriate solver settings for this.
How to set the velocity of rigid domain in Ishell field? How does it relate to the specified velocity in physical field?
Hello,
I am quite familier with comsol, and i have a question in the field of microfluids. I am trying to simulate a microchannel which does not have circular cross section. Is there a way or an approach that i can find the hydraulic diameter of such a channel ?
I want the to know the hydraulic diameter to be able to calculate the pressure drop across this channel.
Any help would be appreciated. Thanks in advance.
Hi
I'm Sai and I want to couple transport of dilute species,laminar flow and geometrical optics for characterizing the mixing of two different liquids in micromixer using an optical sensor.But I did not find any equations with respect to those physics coupling.
Can you help me in finding a solution?
Regards the official example of "Heterojunction 1D" under Semiconductor Modula.
In Study 3, two study steps were utilized. the first one "In order to get a faster convergence, use the continuation parameter ramp to provide a good initial value to the nonlinear solver (10% of the desired value). The latter basically ramp the doping and the themionic current to their final values."
I still don't understand what this step has done. It solves the structure with different continuation parameter, then
(1) What is the output of this step for the next step?
(2) If the output is the best continuation parameter, by what criteria it is the best?
(3) If the value of the continuation parameter isn’t “1”, does it mean the doping level in the model is changed, according to the above description?
Many thanks!
Hello, I am trying to create a blank material with a specific index of refraction. I have looked through the "add properties option" and I cannot find an index of refraction.
I have been able to find the Relative permeability and Relative permittivity under the baisic tab but I would like to add index of refraction directly to a material.
I can see real index of refraction as a property of air and I can edit it's values to have the value of silica aerogel of 1.03.
For reference I am trying to duplicate the work done here http://lhcb-doc.web.cern.ch/lhcb-doc/presentations/conferencetalks/postscript/2007presentations/T.Bellunato.pdf
Hi all,
I am simulating the heat transfer into a plate with a section of the plate shrinking with time. I would like to perform a parametric sweep that uses defined initial temperature values for the first time-dependent sweep, and then uses the last temperature values from the first sweep as initial values for the second sweep, and so on. How do I specify my COMSOL simulation to use initial values for the first sweep only?
Thank you in advance!
Jan Vincent Carag
Hello,
I have a 3D hydrological model which I have used Darcy's Law to do the groundwater analysis. Then I used Darcy's law results as in Partcle tracing for fluid flow. My model has 3 different layer with different hydraulic conductivity and prosity values. I want to release the particle from a flat surface in my bottom layer and trace the particle to their final destination. Finally, I would like to get the particle tracing results on different layers' top surface (which are non flat). Let explain it more in detail with a simple model (attached file): in the attached model, I would like to realease the particle from the horizontal surface at 2 m and get the particle tracing result of the particle that reach the top surface (for example particle position in z, or particle velocity, ...) at the non-flat surfaces wich are located around 4, 6 , and 8 meters! So far I could get just the results on the top surface (non flat surface located around 8 m); but I was not able to get the the result for the non-flat surfaces at 4 and 6 meters It will be really appreciated if you could help me in this.
Bests, /B
Dear all
I cannot find a good way to define the coils in my motor. I use rmm to do my simulation. Have any try to define your coils with variables? Under the condition of infinitite time, how can I use variable to make my current in a certain time? Or if you had met this kind of problem, hope you can share your idea with me.
Regards
Joey
Why the error: "the last time step does not converge"?
Hi,
I'm kind of new to COMSOL and I'm trying to model the laser induced heating of a silicon wafer. I've looked at the laser heating tutorial given by COMSOL but I'm more interested in the conduction along the depth of the wafer not the surface distribution. I'm modeling a phase change in the silicon with the absortion coefficient that suddenly goes up really fast as we reach the melting temperature and stays constant past it.
The pulsed laser is modeled by a heat source at the surface z=0 that is gaussian in the xy plane, follows the beer-lambert law along the z axis and it's power is gaussian in time (1 pulse).
I know from experiments that the temperature should rise pretty high but it barely changes if not at all. I have tried to change the mesh, the boundary boundary conditions but nothing seems to work.
I've attached the file.
Thank you.