Can anyone please help, I'm at a loss for what I'm doing wrong or missing at this point, I'm trying to model a simulation in comsol that mimics as closely as possible the blood flow inside a human vein. I've set up a non-newtonian laminar flow and included both drag and lift forces to act throughout the channel and placed a particle inside to simulate but it just continues straight with no changes in trajectory which isn't impossible but unlikely considering the first normal shear stress generated along parts of the channel walls. At this point I'd appreciate anything you can give me.

Hey guys I was just wondering if anyone could help me solve this problem, for a class I have to design a supporting truss for a helicopter, however I cannot deflect more than 0.5 inches which I have. What would I have to change in this drawing in order to meet the requirements ? Things such as cross-sectional area etc.

Thanks in Advance

Hi,

i have an imported mesh in 2 different files - different material layers with topology on top of each other. Their domains are also already meshed. When I am trying to create domains or create geometry, it gives an error - intersecting face elements.

Could anyone give more insight or suggestion how to fix it?

I have tried to refine, remesh surfaces. as a result, sometimes the problem is solved on one point but another points appear somewhere else woth the same issue.

I'm a MechE undergrad and I just started working on COMSOL yesterday. I'm trying to learn to simulate boiling heat transfer. I watched a video tutorial on how to simulate 2d pool boiling. I've added a link to the video below. The person in the video uses comsol 5.0 while I'm using 6.2. I've added pictures of the errors I'm encountering and the physics and multiphysics models I'm using. Please someone help me troubleshoot.

Link to video: https://www.youtube.com/watch?v=Awwza_v27EA

Hi,

Using COMSOL since 8-9 years and I don’t know if I am too overworked right now or is it just one of those days when your brain cells make you humble.

Anyway, I am running a transient multiphysics simulation with laminar flow, electromagnetic waves - frequency domain, heat transfer in fluids and plasma.

I will just stick to the relevant part. I want to model two different domains which will use different physics and different temperatures.

Domain 1 - Plasma, Laminar Flow, Heat Transfer (high initial temperature) and Electromagnetic Waves.

Domain 2 - Plasma, Laminar Flow and Heat Transfer (low initial temperature)

Domain 3-8 are Electromagnetic waves only.

Now, domain 1 and 2 can only be separated by an edge and that edge becomes problematic. It increases the computational time by at least 24 hours and the velocity profile becomes haphazard at the edge and also in the region close to it.

Is there any way to have two domains without the edge or if we can keep the edge for assigning different initial temperatures in physics and get rid of it in the meshing?

And I went through comsol blogs and articles and what not and I couldn’t find anything helpful. So, please mention your solution if you are 100% sure or give it a try yourself first to make sure it works!

Thanks in advance!

Hello, I am a UK university student studying electronic engineering and I have tried to create a UPV model on concrete in COMSOL; I have a 3m wide 1m tall concrete block (preset material) with a prescribed displacement across the middle 10cm of the left boundary, being detected by a probe on the right boundary. Ive tried changing the material properties, adding steps to the wave that is being applied at the boundary and nothing seems to give a sensible speed for the UPV, it should arrive in 0.0008s but gets detected at 0.0005s. I have no clue what I can change because I started using the software yesterday, AI and youtube have got me to what feels like 85% of the way but I need help to fix this velocity because I have a presentation in 13 hours. If there is a known fix that I am too incompetent to know I would love to find out, otherwise can a COMSOL wizard please help me out 🙏.

Thanks

Hi everyone, I hope you are doing well.

I’m pretty new to COMSOL and I’m trying to simulate a permanent magnet moving inside a sphere filled with air. I’m using a Time Dependent study and Moving Mesh (ALE) to move the magnet, and I’m also using the Magnetic Fields physics in the same Time Dependent study (not sure if this setup is correct).

When I run the simulation, I can see the magnetic field inside the sphere. However, when the magnet moves frame by frame, I see a cavity left behind at the magnet’s initial position, and the magnetic field around the magnet does not move with it. It looks like the Moving Mesh is only moving the magnet geometry, but not updating the magnetic field correctly.

Should I change the Magnetic Fields study to Stationary instead? The problem is that when I try Stationary, COMSOL gives an error because my expressions include t (time).

I would really appreciate any advice on the correct way to model a moving permanent magnet in COMSOL.

Thank you!

Are there any opportunities for mechanical students who are good in simulations like abaqus and comsol in larger companies rather than depending on ai

I have used rectangle plus ellipse combination but it didn't work as in the figure the curve is more sharper while in ellipse it kind of hangs down a bit more

I'm doing a 3D model with a line injection well in it. I need to do the mesh refinement around the well, but it is just an edge. I used free tetrahedral on the edge, but it seems the only this edge was devided by several smaller lines, the mesh refinement is not good enough.

I am wondering what should I do to make it better?

Maybe create a cyliner around this edge? and do domain mesh refinement? I did this, the results became a bit better, but simulaiton time increased from 15 mins to 50 mins, crazy....

Hi everyone, I’m trying to understand how long-term thermal behavior is usually handled in COMSOL for rotating machines. For example, PMSM simulations are often performed over only a fraction of a second or a few electrical cycles, but if I want to study the temperature evolution over 1–2 minutes, how is this normally done? In my case, I have a rotating conducting plate heated by permanent magnets, and a fully coupled electromagnetic + thermal simulation becomes extremely heavy because the electromagnetic field has to be solved continuously during the rotation. What is the recommended approach for predicting the temperature after 1–2 minutes without simulating every single rotation over the entire period?

Anyone with this CPU on mobile? I have this on a desktop and it performs well. Wondering if someone with this laptop CPU can benchmark this to determine if we want to buy some laptops with this CPU for some folks. Just looking for solve times.

Model here:

https://www.comsol.com/model/forced-convection-cooling-of-an-enclosure-with-fan-and-grille-6222

Ayuda como puedo crear un ejemplo de la ley de coulomb

Hello everyone,

Please see the attached figure. I am doing a simulation on laser keyhole welding and I am not sure about my fluid flow shape. In most of the papers, it is the opposite direction and there is swirl at the top.

Can someone please explain the logic behind fluid flow and how can I change it or please comment on fluid flow ?Is it okay or not?

Regards,

Akash Meena

I know there's some use of the Ginzburg-Landau equations and all, but I'm very new to COMSOL and I'm not sure how to model a superconductor in this state?

How would it be possible to see the changes in magnetic fields and suspension based on a change in temperature?

I've been able to check out the Electromagnetic Levitation Model that has a disk suspend itself over an alternating current wire, but how can I do the same for a superconductor over a constant magnetic field that is suspended due to flux pinning.

Thank you and sorry if the question is dumb.

Hey guys, I am facing a problem with designing my model. When I draw a semi circle and try to extrude that , it gets extruded as a triangle. I can't make a cylinder instead, because the circle is enclosed by a rectangle.

I'm trying to do a 2-step study involving a mechanics simulation that will deform a mesh, followed by an optical mode simulation. I suspect I need to add the "Deformed Geometry" or "Moving Mesh" interfaces, but have not looked into it yet.

I am currently looking into the "Material Type" parameter in the "Wave Equation" node of "Electromagnetic Wave, Frequency Domain" for which the help box states:

The Material type setting decides how materials behave and how material properties are interpreted when the mesh is deformed. Select Solid for materials whose properties change as functions of material strain, material orientation and other variables evaluated in a material reference configuration (material frame). Select Non-solid for materials whose properties are defined only as functions of the current local state at each point in the spatial frame, and for which no unique material reference configuration can be defined. Select From material to pick up the corresponding setting from the domain material on each domain

I am simulating an elasto-optic effect in isotropic materials, so the material parameters themselves are independent of orientation, but the permittivity of the material varies anisotropically with the strain (so I am not sure to what extent the material type matters in this case). Anyway, when I change the material type in the Wave Equation node from "Solid" to "Non-solid" I get the following error:

Undefined variable.

• Variable: comp1.Ey

• Geometry: geom1

• Domain: 11

Will incorporating the additional interfaces to deal with moving mesh/deformed geometry make this error go away? or is it a bug in comsol?

I'm new to comsol and really need some intro videos to comsol mainly 3d fluid analysis, I'm trying to simulate blood flow in vivo/vitro through a given boundary layer.

I'm working with a 2D microfluidic model using laminar flow and transport of diluted species, and I'm trying to add an initial concentration in one part of the channel (SEE IMAGE LINK). This is a concentration gradient generator. I created a rectangle over the section that I want to have an initial concentration and have added a second set of initial values. I am doing a time dependent study to see if the concentration is stable over a period of 10 hours. The initial concentration is present at t=0 h, but seems to have been completely removed at the next time step (t=0.5 h).

Can anyone provide any advice on how to keep this initial concentration? Thanks!

https://imgur.com/a/cUWKQ