Latest Discussions - COMSOL Forums

Line break in plot titles

Fri, 29 Sep 2023 15:04:31 +0000

The below post is related to an archived discussion

To insert a title with a line break, you can add a title in the graphs itself, rather then in the figure. The different lines of the titles, you can put in the description of the different graphs.

Plot RCS

Fri, 29 Sep 2023 12:49:25 +0000

Hi, I'm a student and I would like to graph RCS of a 3D model with a polar graph and with a 3D graph, how should I do it?

How to adjust the weighting factor of a multi-objective function so that the objective function transitions naturally

Fri, 29 Sep 2023 06:03:23 +0000

Dear Mr./Miss., In topology optimization, ually the multi-objective function is of the form: obj=wobj1+(1-w)obj2. Adjusting the weighting factor w is able to obtain the optimization curve of the design. In the research work of others, transition of the whole topology is obvious and clear as w is incremented or decremented, shown in Fig. 1 However, in my topology optimization structure, the problem of adjusting the weight factor transition is not obvious, as shown in Fig. 2. When w=0.5, the overall topology is very much inclined to flow rather than equalizing flow and heat transfer. It is worth noting that I have normalized obj1 and obj2 before optimization. If obj1=Ere/Ebase, Ere refers to the flow dissipation after optimization and Ebase values the flow dissipation in the initial state. So my question is, what are those parameters I need to adjust or observe in order to adjust the weight factors to get the proper topology. Also what do I need to do to perform the prior sensitivity analysis for topology optimization in comsol? Best regards, Gavin.

Acoustics on MPP

Fri, 29 Sep 2023 04:54:45 +0000

Hi. I am new to COMSOL and i am working on micro perforated pannel and i need to get curve of absorption coefficient vs frequency using MAA model backed by an air cavity. can any one help me

Heat Transfer using Electric Current

Thu, 28 Sep 2023 18:59:46 +0000

I am getting high temperature than in the reference research paper I am following when I give 24 V to the copper electrode. Will anyone help me to understand regarding electric heating in comsol.

I am having almost 20 times more temperature than in my reference paper. It means the copper electrode is heating too much in same input and time duration than in the reference paper.

Hydrogen Storage System

Thu, 28 Sep 2023 10:08:49 +0000

Hi, Does any one know how to couple chemical reaction and the generated heat with Brinkman equations and Heat transfer in an hydrogen storage tank

Saving the last iteration of topology optimisation

Wed, 27 Sep 2023 15:03:55 +0000

Dear,

For my project, I plan to perform an analysis on the final iteration of the topology optimization, where the geometry obtained from this last iteration will serve as the basis for the analysis. How can I do this? Is it possible to save the result of the topology optimisation in a new model and then do analysis?

Thank you in advanced!

With kind regards, Dehlia

Possibility to define Fixed Constraints only for certain degrees of freedom?

Wed, 27 Sep 2023 11:57:05 +0000

As part of the topology optimization of a part attached to rods I am looking for ways to restrict only certain DOFs at the mounting points. For example, I would like to restrict the mouvement of the inside surface of a mounting hole only in z direction and not in the other five degrees of freedom. So far I have only found the fixed constraint otpion; however this restricts motion in ALL directions. Does anyone have a clue on how to achieve this?

How can I find the change in diameter with time?

Wed, 27 Sep 2023 10:58:36 +0000

Hi all, I modelled a 3D model of a pressure tube to find the effect of creep on it.

I defined the boundary load, internal pressure, and a creep law.

Now I want to find the change in diameter of the pressure tube with time due to creep at a particular location (along length) of the pressure tube.

How can I find this. Please suggest me.

Thanks

How to calculate the power of a terminal in frequency domain study

Wed, 27 Sep 2023 08:47:11 +0000

I am following the saw gas sensor example. When try to calculate S parameter, we need to fix the input power of the terminal and then perform a frequency domain study. I try to calculate the power from the terminal current and voltage by the equation for average AC power. But the result are not equal to the value I set to the terminal and it looks similar to the S parameter. Does my calculation give the output power? And How comsol apply the fixed power to the terminal in terms of the boundary conditions ?

Rotation angle in rigid connector

Wed, 27 Sep 2023 07:18:05 +0000

Hi,

In Solid mechanic problem, I made a model using a rigid connector between boundaries (as attached figure). The prescribed angle of rotation to the z axis is set 1 (rad). After the computation, the derived value for the rigid body rotation to the z axis (solid.thz_rig3) is just 0.95885 (rad). Why the values are different and how to have the derived value equal to 1 (rad) as the prescribed value?

Thank you!

Cut point 3D analysis on applied loads

Wed, 27 Sep 2023 07:16:46 +0000

I have done a piezoelectric simulation and have added a Cut Point 3D in geometry. Once i compute the solutions I am able to plot the derived variables result like electric potential on that particular 3D point, but I am unable to graph the applied loads (obtained from initial conditions) to plot applied loads and generated potentials in one single 1D graph. For reference my study is time domain and I am applying a dynamic force over my piezoelectric structure,

regarding defining a lower dimension PDE?

Wed, 27 Sep 2023 05:29:00 +0000

Is it possible to define a lower dimension pde in a higher dimension using local co-ordinate system?

For example in an inclined beam if i want to define a pde in its local cordinate system i.e., co-ordinate system along the length of the beam?

Angular momentum

Tue, 26 Sep 2023 21:17:17 +0000

Hi all,

I'd like to determine the angular momentum of a geometry in a time dependent study in COMSOL. The rotational velocity around the center of mass of the system would also be very interesting, but I haven't found a way to do that either. Has anyone else run into this? Because it feels like this should be really easy to do.

gITF with legends

Tue, 26 Sep 2023 17:25:39 +0000

Hi Is there a way to include the legend when exporting gITF file for 3D results ? thanks

Should I add 0 order when I stimulated diffract grating?

Tue, 26 Sep 2023 12:51:04 +0000

Today I stimulated diffract grating through by learning template, if I follow the case ,I can get the same reflect efficiency result picture; However, when I add 0 order under port one , the result changed a lot, so why cause it? and it is need add 0 order or isn't?

beam boundary condition

Tue, 26 Sep 2023 11:25:13 +0000

How to give displacement boundary condition in an inclined beam with respect to local coordinate system?

Gas Diffusion Electrode

Tue, 26 Sep 2023 08:40:17 +0000

I'm working on a model for a gas diffusion electrode (GDE) and I'm trying to understand if it's possible to impose an equilibrium condition between gaseous oxygen and liquid oxygen. In particular, I have a balance equation for the gas and one for the liquid species, and I want to impose the exchange equilibrium on the entire volume in the form [O2_liq] = pO2/K*, where [O2_liq] is the concentration, pO2 oxygen partial pressure and K a constant.

Does anyone know if it's possible to do this and how?

Thank you

List of surface to surface radiation operators

Tue, 26 Sep 2023 06:59:45 +0000

Hi, I'm looking to compute the view factor for some radiation problems. I see the COMSOL tutorials and blog posts mention the operator radopu and radpd, but I cannot find it in the documentation. Can someone point me the documents that lists these functions.

Microwave heating, Magnetic field

Tue, 26 Sep 2023 01:45:53 +0000

I was recently doing a simulation of microwave heating, and I wanted to know the temperature changes at different points by adding probes. How can I modify the magnetic field expression of the probe into the formula of temperature change over time that I need?