Comsol Definition and 223 Threads

Hi Everyone, I have a thousand data points that create a graph of Copper's Thermal Conductivity as it changes from a temperature of 4.5 K to 300K. These points create a somewhat bell-shaped curve, and I have been trying to find the equation to this curve so I can integrate it. I have...

Hi everybody, I've got a problem with the Global Variables Plot in a 3D thermo-structural problem. I want to plot the reaction force for all the stored output times, but the interpolation only takes 7 steps of the solution, although the "times" in my time stepping are 0:.01:10 . In my opinion...

Hello, I am trying to use the electrostatics module in COMSOL ( I just started a few days ago). The other day, I was able to create a 2D box, apply a charge at one side (via boundary condition), and ground the other sides. I solved, and got a neat output, that I suspect is correct. Then...

I have a problem where the coefficient of thermal conductivity changes as temperature changes. Where/how do I input this into comsol?

Hi Everyone, I'm using Comsol v.3.4 to model a 1-meter copper rod experiencing a Temperature change of 294 Kelvin (4K at bottom and 300K at top). I have a slow computer/connection to the server, so I can't see any 3-D images or the Temperature plots. I'm working in the axial symmetry (2-D)...

I'm computing the potentials in a volume conductor. I can get the potentials at any arbitrary location using the File->Export->Post Processing Data. Anybody know what method (and its order) COMSOL uses to interpolate the potentials at the arbitrary locations?

Hi.. I'm trying to do the damped vibration analysis of a cantilevered beam. Although i am choosing no damping in subdomain settings menu, it solves the problem as if the material is damped (the result is a damped vibration signal). Is this is a bug or am i missing something? Thanks in advance

Dear Expertor, I'm just newbie in Comsol program, I have project to simulation the infrared radiation heat for the epoxy. So i would like to know how to specific the infrared lamp in Comsol simulation model. Could you please reccomment some book or some sample file of Comsol. Thanks...

Hello all, I am having a hard time coming up with the proper syntax in order to have COMSOL Script spit out the various eigenfrequencies for a static/eigenfrequency analysis that I am running. Previously I have been using: postmin(fem,'eigfreq_smsld') this works well for recording the...

I'm making a model in Comsol. In it air streams from a pressure chamber through a small jet (1 mm). It seems i am having problems with it because i can't get the tolerance or getting different errors. I have revined the mesh as much as the computer can handle but i stil don't make it. Is...

hi all.. How can i describe initial conditions or initial forces in comsol(like wave forms such as ramp or parabolic)? I couldn't find it in the manual. in ansys, i do it in time steps(in solution options).(like t=0, F=10 t=0.001 F=0) I tried to give initial displacements to the points but...

Hello. I recently obtained a trial version of COMSOL, and was trying to run COMSOL with MATLAB. During the installation process, I clicked option "MATLAB interface" under the "Features" tab. After installing COMSOL, I could not locate the "COMSOL with MATLAB" folder in my Programs menu. Also...

hi, i am about to start working in comsol, can anybody suggest me any books to read for this purpose. regards,

Hi everyone, I am doing a simulation using COMSOL 3.3a... I am using heat transfer module. I have 3 subdomains in my design with sizes in range mm, micrometre and nanometer...the third nanometre block appears just as a line...bt however i was able to give all boundary and subdomain details as i...

COMSOL RF module: urgent Hi i am a new user to comsol RF module. Actually I a want to model the heating of a material using IR waves... can i use the RF module (which illustrates microwave heating as an example) to model the IR heating...do we have options to change the frequency of wave from...

Hi everybody! first of all congratulations for the forum, you have very interesting things here! This is the first time that I write a question, and I would be soooo pleased if anyone could help me. I am working with COMSOL multiphysics program, and I am trying to simulate the flux inside a...

Hi, I'm trying to model the frequency response of a thin PZT disc using COMSOL, but I am not sure how to calculate the impedance Z vs frequency. I defined the current density at the top electrode as I=-imag(nJ_smpz3d) and then plotted V/I using the domain plot parameters in the postproc menu...

Homework Statement How do I set a slope-matching condition in COMSOL? Homework Equations u1x=u2x. The Attempt at a Solution I have used the Dirichlet BC type. I have multiplied and divided by n, the number of equations, on either side of the boundary.

Hi all; I'm trying to write a script that automatically generates a geometry and does the analysis in a for-next loop. It changes specified geometry properties in a for-next step like scaling the geometry. But I've got a problem about subdomain IDs. Although the main geometry isn't changed...

Hello, I hope some expert can help me: What do I want? I am modeling magnets in script Comsol in 3D. All I want to do is to displace a magnet. and then compute forces and moments applied to it. This works in Comsol (2D): draw{1} = rect2(.5,1,'pos',[0;0]); draw{2} =...

Hello, I have a file with points and I want to create a 3D geometry in Comsol, but it's impossible to load a txt file in this software. In Comsol we can import something called "geometry object" and I know it's possible to create this geometry with Matlab but I don't know how to do. Can...

Hello, This is the first time I'm using COMSOL on a problem where I have multiple subdomains within the domain. Previously, I have only been using one domain/one set of equations/Two global sets of BC's. I've been having a hard time thinking of a solution to my problem. I have 3...

Hi, I want to model the em wave interaction to a metal ...can i do this without the RF module? I want to model the coupling of em waves to metal particles, so is it possilbe to do without RF module since my organisation have not subscribed for RF module... pls reply

hello there I'm using comsol multiphysics acoustic module. so: 1) acoustic model / pressure acoustics / time harmonic analysis 2) draw a circle and do boundaries (F7) = radiation condition (p=0) so this boundary absorbs all the acoustic pressure... 3) then made a mark in the middle and...

hi, I'm a chemical engineering student with a little problem with Comsol multiphysics; in practice, i have to solve a problem of diffusion in a solid sphere. after drawing the domain, i have to set a boundary condition on sphere's surfaces. this condition, for my problem, is FLUX=Kc(Cb-C) and...

Hi, I am using Comsol with Matlab. I have a loop in my M-file. And it seems that the memory usage of my program increases as the loop increases.. It is a very intensive program, so after a while, the program stops because there is no more memory. For example, I am running this program on 1 CPU...

Please can anyone tell me how to set this up? I know how to do the required settings in the Physics/Period Conditions. However, to fully implement it, I'm also required to choose boundary conditions in the 2D incompressible navier stokes solver (e.g. wall, inlet, outflow, open boundary...

I personally inform that i still beginner in Comsol Script. I wanted to learn about the comsol, how to simulate the graph. I tried plot(x,y). but i need to use this function simulate(Ss1,(U1,U2)). But at the end, it show Syntax error. Heres the details of the code: Ks = 600000...

Comsol data transfer (urgent) I am trying to model a system which should simulate in two modules in Comsol. First I have to run the problen in electrostatic toolbox and then load the field data generated in this model to the in-plane wave model and run it in this model. Is anybody know how to...

COMSOL Rectangular mesh (VERY URGENT) I am trying to modify the mesh of a COMSOL simulation. I need to make my mesh rectangular instead of triangular that COMSOL defined already. Thanks. Engin

Homework Statement Construct a simulink model of the extended system that fully represents it. Hint: If KST tends towards infinity the new model should be the same as the old provided the mass of the car body is unchanged. M = 1200; KST = 15000000; MH = 60; Kv = 3.2e+004 Homework...

Hi there, I'm using comsol for the first time, and I think I've got everything working, except that I need to write a boundary condition that is dependent upon the gradient of a variable. How do I tell Comsol to take the gradient? I suppose I can define my own function, but I don't even know...

Hello, I am using COMSOL (RF modul) for some time now to calculate the eigenvalues (modes) of optical fibers. So far I changed all the params from hand in the software. But it is getting anoying to change a parameter (the wavelength) and to recalculate if one wants to calculate for many...

Hello everybody! I have the problem that my comsol generated m-files contain a lot of repeating entries and old values which have been changed in the process of creating the *.mph-file. Comsol writes in the knowledge base: "When saving a model as an M-file it contains by default all the...

I am currently just running a normal 3D incompressible flow problem in COMSOL 3, and end up with the following error: Error: Time 0: Error in residual computation: The_relative_error_is_greater_than_the_relative_tolerance For the direct solver. Last time step is not...

Hello everybody, Thank you in advance for your help. I am trying to model thermal contraction of an elastic solid in Comsol. I am sure this is a simple model, but I am a new Comsol user and it is not obvious to me. My goal is to model the stresses within an elastic solid, that arise...

I'm a student with no much experience with FEA and COMSOL. I'm trying to model the heat transfer from a heated cylinder. The cylinder has diameter of about 0.18 m and height of 0.36 m. The cylinder is hollow with holes from one side to the other side. I'm interesting in finding the temperature...

Hello, Now I am working on the convection and diffusion problem with chemical reactions. The question is simple (but the answer is hard to me...) : I want to put a MATLAB function in the generation term, ex: the original one is " -k*c" , and I write a function r_c(x) which returns -k*x. In...

Hi, Is there anyone who can help me with COMSOL Script? Is there anything wrong with this statement: flclear fem g6=rect2(1.0E-6,11.0E-6,'base','corner','pos',[0,0]); clear s s.objs={g6}; s.name={'CO1'}; s.tags={'g6'}; fem.draw=struct('s',s); fem.geom=geomcsg(fem)...

Hi everyone, I'm doing an analysis with Comsol on an Impeller. Shortly, it is a roller (cylinder) that applied a pressure on a blade (shape of an helix with variable pitch; I have the equation of the bade) at a specific radius to deform it. I've done my assembly in Catia (impeller and...

Hi! I have this problem. I have a cylinder filled with a hot Nitrogen gas (340 K) under 3000 psi pressure. The cylinder is exposed to the air and I need to find a temperature distribution in this system as a function of time. I am using Heat Transfer model -> Non-Isothermal Flow. The...

Hi I'm trying to get comsol multiphysics to first define an inline function with 1 variable and 4 parameters, and then run fzero on that same function. I can do it with two parameters, but no moore. This works: clear myfun=inline('exp(y).*cos(x)+z', 'x', 'y', 'z'); x1 =...

I have a question regarding communication PSpice software with Comsol Multiphysics. I was searching for some examples but I did not find anything. I would like to simulate a certain element from Spice scheme with Comsol. Anyone have any experience with this? I think that Comsol should have...

Hi guys, I have a question in using comsol software, particularly on heat transfer. Its a 2D geometry. A rectangle whereby heat is applied on the top surface at the particular point and the 3 sides are thermally insulated. As more heat is applied over time, a hole will be created. A...

Hi, I am using COMSOL Script and I am trying to figure out something. Let's say I am only solving one PDE which solution is 'phi'. And I am doing a parametric study, so I am solving it for different biases 'Va' from 0V to -1V. My geometry is simply a rectangle. As part of the PDE, I have a...

Hi I am working on a project to do a coil simulation using COMSOL to determine inductance and resistance variations with frequency. I have a CAD file for the geometry but I need help because I am having serious difficulties with the rest. Can anyone help pls? thanks alot

Hi i'm solving a system of 6 ODE's (time dependant) and wish to export them to a set or 1 of ascii files that can be imported to origin (the format being the variable against the time) . is there a way to do this? also is there a way to run a set of eqns changing the some constants each time...

Hello, I m a student using COMSOL Multiphysics. I have to admit that I am new to this software but it is giving me loads of problems. I am trying to model an eddy current sensor by modelling the coil and a plate (mild steel). The size of the plate is 17mmx17mmx3mm but I had no problem with...

Hello, anyone with some experience in Comsol? I have a few basic questions on the RF module thanks!

Hi All, I am pretty new to COMSOL. I want design model of a sensor with four electrode. This sensor mainly based on impedance spectroscopy principle. The model should measure the distance and thickness of the obstacle due to change in capacitive impedance of electrostatic field between the...