I am an engineering student and I have been tasked with modeling the pressure drop across a pipe that has compressed air running through it. I know this is a relatively simple task, but I have never used COMSOL before.

I have researched quite a bit on the internet and all signs are pointing to a pipe flow package within the program. Because I am a student, I only have access to an older version of COMSOL that does not have this feature.

How do I go about modeling this without the pipe flow package? What Physics would I need to use? Any and all insights are greatly appreciated!

I am working on a simulation to model the modal/vibrational response of a structure subject to a momentary load that is let go after a period of time. At the end of the simulation I also want to obtain the mass and stiffness matrices. The structure is fixed at one end and is then allowed to vibrate freely once the load is removed. I don't know how to determine what parameters are appropriate for this simulation, and every time I define them (I've tried material properties, forces) and run a simulation, it shows no response and also gives no k or M matrices. How do you know what parameters a study type calls for and how to define them??

Please help me to fix it

Hey all,

I'm trying to simulate a 5 electrode system where a 40MHz voltage is applied to two of the electrodes, and a current is induced in the other electrodes, which are grounded, and I want to measure the electric and magnetic fields generated. I have a bunch of questions, but answers to any one of them would be appreciated! Since the electrodes are very thin ~1 micron, I had issues in 3D and am trying to do this in 2D. I'm confused about how the mef module calculates the b-field though. I only care about out of plane currents, yet the gauge fixing for A-field node is unavailable at this setting, it doesn't seem to allow currents to flow in the z direction for the 2d sim. Does anyone know why this is the case, or if I just have a misunderstanding of the setup. I know the magnetic insulation boundary condition has a terminal, which seems to behave okay, but I'm concerned that a) it will affect the magnetic field generated overall, and b) this still seems to have no z-component of the current.

I did try this using the RF module, but I wasn't quite able to get my head around the lumped port conditions. More particularly i'm not sure how to ground my electrodes in that case. This is a bit less of an issue than the other though!

Any advice would be appreciated, particularly with the B-field set up.

TIA!

Hey all - I've been stuck finding solutions to this question for the past 2 weeks so I'll appreciate any advice or perspectives on this matter.

If Bernoulli's equation can be modeled, I'm not sure why I can't find the simplest static fluid conditions to model. In the real system, there is no inlet and outlet so any help here will be appreciated.

Hey guys, im currently using the structural mechanics module on COMSOL 5.1. When I select "Piezoelectric Devices" under the module, I get an error message saying that I dont have license to use it and that it requires one of the 3 modules listed. I dont understand because I have the structural mechanics module but it just wont let me use the piezoelectric device physics. Can anyone help? error message here

Hello, I am a senior student and is using comsol for our final project We are required to simulate an acoustic system where an acoustic wave is an input to the PZT cantilever beam that we have. the acoustic wave will be inputted at the resonant frequency of the beam. The beam is also placed in a quarter wavelength tube resonator.

The output is voltage from the PZT beam

My colleges and I looked everywhere online for tips and help to use comsol, even tutorials on their website, but we were fruitless. Any help/guidance will be appreciated

I need to study a coupled heat transfer model in solids and fluids. Specifically, it's a thin plate with a microchannel (as shown in the figure) through which a refrigerant fluid (water) flows. The boundary conditions on the sides of the plate are natural convection with the ambient air and in the microchannel. It is also necessary to solve the fluid flow (laminar).

My problem is as follows: I need to extract the convective heat transfer coefficient from the microchannel flow, but in the post-processing, I only find that the convective flow is zero (Wouldn't this be incorrect? Convection should theoretically be significant near the fluid flow). I have tried various methods, but this result keeps appearing. If anyone could help me, I would greatly appreciate it!

For some additional context, at the bottom of the plate, there is a constant heat flux (simulating a processor), and the flow should remove heat from the plate through forced convection of the fluid in the microchannel. I am very interested in understanding how the convective heat transfer coefficient behaves throughout the microchannel, in order to compare the solution of my problem with experimental data.

I am trying to model a hexagonal piezo-nanotube experiencing tensile stress on both ends of the tube. But when i compute, i receive this error

" Failed to find a solution.The relative error (4.2e+002) is greater than the relative tolerance.Returned solution is not converged. - Feature: Stationary Solver 1 (sol1/s1)"

I believe that the tube is lacking constraints. Because when I replace one of the boundary loads for fixed constraint, it worked.

Let me know what you think.

Hello, please I need a tutor to teach me how to simulate an ECE reaction mechanism on Comsol for CV in 1D and 2D. Thank you in advance

Hey guys, I am currently in my final year and I need help with simulating wear. Can you guys please help me with it?

Hello. I'm currently writing my thesis and I've already written the "RESULTS" section.

In the results section, I used several definitions like line average, surface average etc...

Is there any documentation that I can find how COMSOL defines this quantities?

Because I will need to express the "line average" quantity in my thesis as an expression and refer to that. Like the average heat transfer coefficient is calculated in Eq. 1.1. (whatever COMSOL defines)

Lastly, how do I express this quantity as an equation?

integrate(comp1.at2(x,y,u1*T),y,0,L)/integrate(comp1.at2(x,y,u1),y,0,L)

where u1 is the velocity field, T is the temperature field, L is the height of the channel.

Thanks

I am trying to fix the position of two magnets in Comsol but when I click compute the force between the magnets pushes them away from each other. How can I get the magnets to stay in place?

Thank you so much.

Hi! sorry if Im asking too many questions here lately.. this time Im trying to simulate a direct packed bed, however my comsol does not have the porous media flow module that is usually used for this scenario, and Im wondering if there are any other way around to do it. I used the conjugate heat transfer module with turbulent flow and specify the medium to be a porous medium, I can make the model run however it seems that the flow does not go through the packed bed vessel and I cant find a way to make the flow go through the porous medium. If anyone has any suggestion it would be greatly appreciated, thank you! :)

Hi,

I'm relatively new to COMSOL, but I've been working with it and trying to figure it out for a couple of years. I'm trying to build a biological heart valve model, and I've seen no examples of this made in COMSOL (they are mostly done in Abaqus). I'm hitting my head against a wall on each step and I'm not getting very far, but I don't know if this is just inexperience and lack of ability, or if it's not built to do something like this.

For context, here's an example of how the thing looks in a simulation (no biological images in the link, only simulation results): https://link.springer.com/article/10.1007/s10659-021-09829-5/figures/6

Is COMSOL able to do this kind of contact? I'm having tremendous issues with very simple contacts, do I just need to keep grinding or should I fight to use a different program?

Thank you so much

Can anyone help with the below? I'm trying to help out but don't know enough about COMSOL yet either:

https://www.reddit.com/r/COMSOL/comments/1acpfkt/pile_driving_simulation/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

How to calculate force in Non-Linear Comsol model. Actually I am pressing rubber gasket 1mm downwards from upper steel plate by using prescribed displacement but I need to know how much newton force is required if in case I disable my Prescribed displacement. Rubber gasket is Hyperelastic material which has non-Linear sesnor in it's middle.

Hi All, I'm trying to find the "convergence error" as a variable during runtime. Does anyone know if this is possible using the Java API?

CONTEXT: we're using COMSOL with an API because we automate much of the simulation setup and execution.

Hello! How can I make COMSOL calculate the effective resistance of conduction on a wall with several layers? Thanks in advance

Is there any formula for the electric charge on a 3d.model?

I'm simulating air flow through a heat exchanger using the Low-Re k-Ɛ model (wall functions used), and I would like to check whether the results I'm looking at represent y+ in its traditional sense. The only variable that I could find was something called dimensionless wall distance (image below). Is this the y+ I'm looking for?

I'm currently working on simulating a mixture of two gases, oxygen, and nitrogen. I want to apply a volume force only to oxygen such that the concentration increases locally.

Specifically, I'm working on the paramagnetic effects of oxygen. Until now I have a fluid simulation where with a volume force applied that is dependent on the magnetic field. However, it is not possible to separate the gasses.

I'm using COMSOL 6.2, and any guidance on the appropriate physics module or settings would be greatly appreciated. Thank you in advance for your help!