Hi, I need to specify initial values for strains inside a domain such that the current geometry has some stress-free prescribed strains.
Could anyone give a hint on how to do so.
Thanks, Mo
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Initial Value for Strains
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Chronoamperometry Measuring Current due to Electrode-Electrolyte Diffusion at Electrode Surface
Good Evening,
I am currently trying to perform a Cottrell Experiment by simulating electrolyte diffusing into our working electrode of interest which in this specific case is a 3D thin film. I used COMSOL's "1D Thin Layer Chronoamperometry" from the Electrochemistry Module Application Libary Module as a basis when constructing my 3D simulation. The goal is to build a model that generates current which matches up with the current calculated from the Cottrell Equation.
However, my results show that the Cottrell Equation predicts higher currents than what is being measured at short times and the resulting concentration profile definitely does not match was is expected in this type of experiment.
My principle investigator predicts the deviation could be a result of how I set up one of my boundary conditions. However, still learning how the Electronanalysis interface works is making it difficult to figure out if I set up anything incorrectly or if I am missing anything entirely from my simulation settings. I am using an Academic Class Kit License Version 5.2a.
I have attached screenshots below if they help clarify as the COMSOL file itself was too large to attach.
Any pointers or assistance would be grealty appreciated! Thank you very much for your time.
Joe Gonzales ; University of California, Irvine
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Simulation of steam condensation in tubes using two-phase flow field
I have seen some cases of phase change on COMSOL website, but they are all about evaporation and liquid-solid phase change. I have not seen condensation simulation. How to use multiphase flow to simulate steam condensation in tube?
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How can I monitor the Level-Set's boundary in time?
How can I monitor the Level-Set's boundary in time? To simulate the droplet impact on the wall. The Level-Set's boundary means the line when the ls.Vf2=0.5. when using integration operator, The result is not necessarily accurate (slightly smaller). when using maximum operator, The result will be fluctuating. I don't konw how to upload a picture, it's like, now it's 1mm, next timestep suddenly changes to 0 or 1e-3(grid size), and next timestep changes back to a normal variation, and so on.
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I'd like to simulate thermal deformation of a thin glass due to a laser heating with extra pressure.
Hello,
I just attached the concept file that shows what I want to simulate. I'd like to estimate how a thin glass is deformed when it is heated upto the softening temperature by a laser beam under extra pressure.
Is there a good example or tutorial that I could try?
Thank you.
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Electrical Double Layer Simulation
Hi There,
I am having problem while simulating the 3D electricl double layer problem. The specific errors will ocur during solving multiphysics problem. I am attaching the .mph file for you consideration.
Thanks
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Issue regarding coupling piezoelectric and Fluid surface interaction
Hello,
I am trying to simulate piezo actuated valve. I am having some problems with couplaing piezo and fluid surface interaction. I have used moving mesh for fluid domain however, the fluid domain does not seem to move according to the structural deformation (caused by piezo). I have used fully coupled along with iterative solver. However, I seem to get this error.
- Feature: Stationary Solver 1 (sol6/s1)
Undefined value found.
- Detail: Undefined value found in the equation residual vector. There are 218 degrees of freedom giving NaN/Inf in the vector for the variable comp1.spatial.u. at coordinates: (-0.00045691,-0.0002), (-0.000503455,-0.0002), (-0.000410365,-0.0002), (-0.000496554,-0.000191171), (-0.000451259,-0.000190817), ...
There are 218 degrees of freedom giving NaN/Inf in the vector for the variable comp1.spatial.v. at coordinates: (-0.00045691,-0.0002), (-0.000503455,-0.0002), (-0.000410365,-0.0002), (-0.000496554,-0.000191171), (-0.000451259,-0.000190817), ...
Can someone please let me know what could be the problem?
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Calculation of dielectrophoretic force on a line
Hi,
I am performing a 2-d simulation in COMSOL 5.5 in which a microfluidc device separates different cells using dielectrophoresis. I want to compute the dielectrophoretic force acting on different particles on a vertical line. I have tried the built-in expressions from COMSOL, but they do not work out (maybe I do not know how to do such an action). Does anyone know how could I do that?
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Draw point graph for difference between two points
I have 2D time dependent simulation of cooling. I have created two "Cut Point 2D" in the Results/Data Sets. I can draw line graph for boths points using "1D Plot Group" and two "Point Graph" inside. The result graph is the change of temperature with time in boths points.
But I need to draw the difference of temperature in these two points as function of time. Any hints?
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question about small imaginary part for eigenfrequency
Hello all,
I am running a study for acoustic in a hard wall cylindrical tank. The problem can be easily solved by separation of variables. Theoretically, the eigenfrequencies are all real. But why the eigenfrequencies solved in comsol included imaginary part, such as 1847.9832949527051+8.535829728636379E-12i. All imaginary parts are very small which are compared with real parts. How and why does this imaginary part exist? I am really confused about this part.
Regards.
Margaret
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geometry updating from matlab through comsol livelink
how do i update the values in comsol for matlab and matlab for comsol?
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Electrical currents in porous media
Hello!
I am doing simulation of saturated by water sand rock (porosity 0.35). No flow of water, but on the side borders I am applying eleсtric potential difference. Electrical current pathing through water accumulate temperature raising in the rock.
However I can not combine two modules: Electrical current and Heat transfer in Porous media. Comsol requires heat transfer parameters for rock and water, but electrical parameters - only for rock, without water. It can not do both.
How to solve this problem? Am I using wrong modules?
Thank you!
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Simulation of 2D and 3D optical fiber for frequency domain for mode analysis and boundary mode analysis using comsol 5.5.
I want to know how to simulate 2D & 3D optical fiber. (Actually I simulated 2D already). I am facing problems in 3D. Just guide me regarding boundary conditions ie condition for scattering at entry and exit. Should I apply scattering condition at core or cladding or at both.? Conditions at Port. whether single port is enough or need to apply port at both ends. Should I apply port at core or cladding or both.? What is role of polarisation in boundary mode analysis.? How to apply it.? You can suggest some model or references and simulated desigh as well. Also sometimes it gets out of memory during meshing and computation. any critical information regarding meshing. Tell me something about limitation of system. I am using 32 gb RAM. Anything relating to domains of geometry limiting the outcome. Thanks in advance.
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Dynamically create export data file name
Hello, I want to export data after simulation. I would like to include the variables I defined in the Component 1 > Definitions > Variables section into my output file name. For example, if I use T = 300K, bias voltage = 1V, dopant concentration (N_D) = 10 um^-3, I want the output file name to be something like that T_300K_V_bias_1V_ND_10um^-3. I don't want to input the filename manually because it is cumbersome. Is there a way to export the file automatically?
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Optical microscope image simulation
i am trying to simulate an optical microscope image of a 4 micron diameter sized particle which is placed between an analyzer and a polarizer under 400-700 nm white light.
Particle has internal ordering of small platelets which gives rise to maltese cross pattern much like liquid crystals. I have tried using the RF module to simulate the scattered field in plane polarized light. Do you think Enorm^2 would be what i am seeing as my optical microscope image? or the far field is being projected on the camera in optical microsocpe? any help or guidance will be greatly appreciated.
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Meshing 2D Material
Hello!
I am new at using COMSOL Multiphysics, and I am currently learning how to use it in order to simulate the heat flux across a 2D Material that is deposited between a heater bar and a sensor bar. I am currently struggling to mesh the model because the aspect ratio of the thin film is so high (I made my thin film as a block of dimensions 0.2um, 10um, and 6A). I was wondering if there was a way to possibly maybe make seperate meshes for the rest of the model and the deposited material, or if there was another work around for this issue.
Thank you, Annalies Tipton
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Bulk temperature
Hello I am simulating annular flow in 3D. I want to write the expression to calculate bulk temperature in 3D but every time I faild. Can COMSOL experts can help me to write this expression
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Instant decrease of the temperature after the voltage pulse
Hello, dear colleagues!
I am pretty new to COMSOL and nowadays I am making a model with the Heat Transfer in Solids module. I am applying voltage pulses to my structure and looking at the change of the temperature, that happens due to joule heating. The temperature distribution looks great if I apply nanosecond pulses. But as I start working with millisecond voltage pulses the temperature after the end of the pulse instantly decreases, the model has no gradual relaxation of the temperature at this time scale (even if the pulse heated the structure very much). Same thing happens with heating, the heating happens almost instantly. I have already tried to change all of the parameters, but it didn't work. What am I missing?
Thank you in advance and I wish you luck with your models!
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Modeling Anisotropically Expanding Domain
Hi,
I am attempting to model a 2D reaction-diffusion system in which the overall domain size increases as a function of local concentration. I've done this using a deforming mesh and prescribed mesh velocity. However, I also need the mesh to expand from inwards in the case of a concentration peak inside the domain but zero concentration at the boundary, e.g., cell division. Is there a straightforward way of achieving this?
Thank you!
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How to use a cylindrical coordinate in solution？
I want to extract the rotaion angle of the model from the results, but I don’t know how to use the cylindrical coordinate system in post-processing. Help me please. In addition, I want to know why the deformations u, v, w in Comsol contain plural information. What does this mean?
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