I’m new to COMSOL, and I was hoping someone here would be able to help me. I am trying to model fluid displacement in a pipe. I could use the two-phase flow module, but I don’t need that level of precision for my application and it seems to greatly increase computation time. I really just need a perfectly sharp interface, and even assuming plug flow would be sufficient for now. Is there a way to implement this? Thanks!
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Sharp Fluid-Fluid Interface
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Colors For 2D Plots
Hello,
I have a parametric Sweep for 10 data point. Then I need to plot them in a 2D Plot with a legend. I have done that but some colors recycle, so it can be hard to distinguish them. Is there a way to add more colors to the table or get a different style of line, like dashed??
I have a parametric Sweep for 10 data point. Then I need to plot them in a 2D Plot with a legend. I have done that but some colors recycle, so it can be hard to distinguish them. Is there a way to add more colors to the table or get a different style of line, like dashed??
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Show parameteric value on plot
I've made a model of a hi-pot test setup to visualize how the electric field changes at a discontinuity as the conductivity changes (fixed potential).
I'ts working great, but now I want to make an animation of the results. I can create the series of 2D plots without a problem, but I don't know how to show the value for the conductivity on the plot, making it difficult to distinguish between them.
I'ts working great, but now I want to make an animation of the results. I can create the series of 2D plots without a problem, but I don't know how to show the value for the conductivity on the plot, making it difficult to distinguish between them.
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Hyperelastic anisotropic material modeling problem
I have a hyperelastic anisotropic modeling problem. There is a swelling for the the body. That is to say, the determinant of the deformation gradient equals a fixed constant other than 1. Does anyone knows how to impose such constraint in Comsol? Thanks for your answers.
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Easy way to convert a complex solid model to shell model
I am working with a complex structure with formed sheet metal and tubes. Wall thickness of ~.030" with linear dimensions on the scale of 8 to 15". Definitely a problem that would benifit from a shell model.
However, there seems to be no easy way to collapse the solid forms down to shells/boundaries.
And with over a 1000 boundaries, manually selecting the outer or inner surface of the solids seems to be a very tedious task that will be prone to errors.
Is this the only way in comsol to set up a shell model?
I rememeber 10 years back using Pro/Mechanica being able to pick a thin walled part and collapse it's boundaries down to either a midplane, inner or outer boundary.
Comsol does not have anything like this?
However, there seems to be no easy way to collapse the solid forms down to shells/boundaries.
And with over a 1000 boundaries, manually selecting the outer or inner surface of the solids seems to be a very tedious task that will be prone to errors.
Is this the only way in comsol to set up a shell model?
I rememeber 10 years back using Pro/Mechanica being able to pick a thin walled part and collapse it's boundaries down to either a midplane, inner or outer boundary.
Comsol does not have anything like this?
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charged particle tracing help needed
hello, i have a simple box with relative permittivity and electric conductivity = 1.
with the mef module i created a magnetic field along the x axis with 10 A/m.
i used a working plane inside the box to create a circlular plain as the inlet surface for the particles.
in the cpt module i gave the particles a starting velocity of 50 m/s along the z axis.
i also added a magnetic force to the cpt module that uses the field created from the mef module.
the stationary study creates the solution for the magnetic field, as expected.
in the time dependent study i excluded the calculation of the mef module as shown in the magnetic lens video
www.comsol.com/video/209
my problem is that i dont get any resulting particle trajectories. the particles just sit on the inletsurface. i just want to see them fly a curve through the magnetic field due to lorentz force.
i attached the file to exclude any misunderstandings, thanks for help
with the mef module i created a magnetic field along the x axis with 10 A/m.
i used a working plane inside the box to create a circlular plain as the inlet surface for the particles.
in the cpt module i gave the particles a starting velocity of 50 m/s along the z axis.
i also added a magnetic force to the cpt module that uses the field created from the mef module.
the stationary study creates the solution for the magnetic field, as expected.
in the time dependent study i excluded the calculation of the mef module as shown in the magnetic lens video
www.comsol.com/video/209
my problem is that i dont get any resulting particle trajectories. the particles just sit on the inletsurface. i just want to see them fly a curve through the magnetic field due to lorentz force.
i attached the file to exclude any misunderstandings, thanks for help
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try/catch in matlab for COMSOL
I am doing a parametric sweep in COMSOL with the geometry. The problem is, it is a large parameter space and a few combinations which would be unreasonable to check give an error. It is a stationary solver and what I need is something in COMSOL matlab code to tell me if there is inverted geometry or too many iterations such that I can skip that set of parametric values. I get the error:
For example, can I have COMSOL output the iterations as it solves such that if it hits a certain amount, I can quickly tell if I need to skip that set of parameters. This is inside a huge FOR loop as I need to sweep over a very large parametric space.
"??? Java exception occurred:
Exception:
com.comsol.util.exceptions.FlException: Failed to
find a solution for the initial parameter
(rethrown as
com.comsol.util.exceptions.FlException)
(rethrown as
com.comsol.util.exceptions.FlException)
Messages:
The following feature has encountered a problem
The following feature has encountered a problem
Failed to find a solution for the initial
parameter
Maximum number of Newton iterations reached
Returned solution is not converged
- Feature: Stationary Solver 1 (sol1/s1)
- Error: Failed to find a solution for the
initial parameter."
For example, can I have COMSOL output the iterations as it solves such that if it hits a certain amount, I can quickly tell if I need to skip that set of parameters. This is inside a huge FOR loop as I need to sweep over a very large parametric space.
"??? Java exception occurred:
Exception:
com.comsol.util.exceptions.FlException: Failed to
find a solution for the initial parameter
(rethrown as
com.comsol.util.exceptions.FlException)
(rethrown as
com.comsol.util.exceptions.FlException)
Messages:
The following feature has encountered a problem
The following feature has encountered a problem
Failed to find a solution for the initial
parameter
Maximum number of Newton iterations reached
Returned solution is not converged
- Feature: Stationary Solver 1 (sol1/s1)
- Error: Failed to find a solution for the
initial parameter."
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Can I use COMSOL to solve integral equations?
Dear all,
I have some integral equation to solve. Can I do that with COMSOL or I always need to change it to PDE?
Thanks a lot!
I have some integral equation to solve. Can I do that with COMSOL or I always need to change it to PDE?
Thanks a lot!
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give specific values for every mesh point of a boundary as boundary condition
hey everybody,
is it possibly to give different values for all points of the mesh on the boundary, respectively?
for example, just a vector containing as many values as i have boundary mesh points, or something including the coordinates/mesh point coefficients -- specifically, i want to use a solution of another study at one boundary as new boundary condition for another study, both at the same geometry+mesh. should be possible, no? (in fact, i want to use the old solution, but add to every value a time-dependent term, but this should work then as well.)
please let me know if you know anything helpful, thanks alot.
kind regards and all best,
sabine
is it possibly to give different values for all points of the mesh on the boundary, respectively?
for example, just a vector containing as many values as i have boundary mesh points, or something including the coordinates/mesh point coefficients -- specifically, i want to use a solution of another study at one boundary as new boundary condition for another study, both at the same geometry+mesh. should be possible, no? (in fact, i want to use the old solution, but add to every value a time-dependent term, but this should work then as well.)
please let me know if you know anything helpful, thanks alot.
kind regards and all best,
sabine
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Please send me tutorial for ultrasonic wave propogation through liquid
I need tutorial on Ultrasonic wave propogation through liquid.
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Adaptive meshing
How do I implement adaptive meshing in a 2D mode in COMSOL 4.3a.?
--
MKSharma
--
MKSharma
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Adaptive meshing
How do I implement adaptive meshing in a 2D mode in COMSOL 4.3a.?
--
MKSharma
--
MKSharma
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Hydraulic Conductivity in Reacting flow in porous media
Hello,
Does anyone know if the hydraulic conductivity is still measured in the Reacting Flow in Porous Media node in COMSOL 4.3a? In a similar node in version 4.3, I could measure the hydraulic conductivity for a model, but now I can't find it anywhere! I suppose I could just use the permeability input, but I would prefer to alter the conductivity.
Thanks,
Kelley
Does anyone know if the hydraulic conductivity is still measured in the Reacting Flow in Porous Media node in COMSOL 4.3a? In a similar node in version 4.3, I could measure the hydraulic conductivity for a model, but now I can't find it anywhere! I suppose I could just use the permeability input, but I would prefer to alter the conductivity.
Thanks,
Kelley
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What Physics I need for a liquid cooling problem with phase change
Dear everyone,
I am totally new to COMSOL. Now I am working on simulation of a cooling system. It is a melted material thrown to another liquid (e.g. water). This may cause phase change of water from liquid to gas. In the meanwhile, crystallization process goes on for the melted material. I was wondering what the physics I need for this simulation. I know I need heat conduction and CFD. Could anyone tell me some more detail? Your help is highly appreciated.
Ming
I am totally new to COMSOL. Now I am working on simulation of a cooling system. It is a melted material thrown to another liquid (e.g. water). This may cause phase change of water from liquid to gas. In the meanwhile, crystallization process goes on for the melted material. I was wondering what the physics I need for this simulation. I know I need heat conduction and CFD. Could anyone tell me some more detail? Your help is highly appreciated.
Ming
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Ejection step in injection molding
Hi,
I am trying to simulating the ejection step of injection molding process using Comsol.
After filling plastic into mold cavity, and packing stage, the solidified plastic part is ejected out of mold.
Before the plastic part is ejected out of mold, the plastic part is constrained in the mold. The residual stress accumulated during the filling and packing stage(solidification) will be released when the part is ejected out of mold.
Can anybody give me suggestions about how to model the ejection of plastic? I know the boundary conditions should be set to ambient conditions,i.e. the fixed constraints is removed and set to 0. But It doesn't work in comsol.
Thanks.
Eric
I am trying to simulating the ejection step of injection molding process using Comsol.
After filling plastic into mold cavity, and packing stage, the solidified plastic part is ejected out of mold.
Before the plastic part is ejected out of mold, the plastic part is constrained in the mold. The residual stress accumulated during the filling and packing stage(solidification) will be released when the part is ejected out of mold.
Can anybody give me suggestions about how to model the ejection of plastic? I know the boundary conditions should be set to ambient conditions,i.e. the fixed constraints is removed and set to 0. But It doesn't work in comsol.
Thanks.
Eric
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study computation
hi,
suppose if i use 3 different studies for three physics in my model do i need to compute each study one by one or 3rd one directly..
suppose if i use 3 different studies for three physics in my model do i need to compute each study one by one or 3rd one directly..
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FEM error
Hello every one.
i am new to this COMSOL and with the help some tutorial i learned how to use. i am much familiour with Matlab.
i want to ask 1 question, which i am facing in my most of the models.
let me excplain you how i make model and use. may be i am doing some mistake there.
1) i made my model in MATLAB using COMSOL functions .
2) Then i load it COMSOL using file -> import -> Geometry objects. assign sub domain and boundary conditions. choose solver if required and save the model in (.m) MATLAB file.
using this Matlab code i assign different conductivity and permitivity with other same boundary conditions.
till here its working fine,
now when i made one big cylinder C1 with the radius of 0.5 cm and cylinder C2 with the radius of 0.05 cm. apply step (2).
now in the MATLAB code if i change the radius of C2 0.1 cm i gives me error
??? Error using ==> fem2jxfem at 60
Errors found in FEM structure.
Error in ==> multiphysics at 81
jxfem=fem2jxfem(fem,femname(inputname(1),fem),{'lib'},false,false);
i checked the no of boundary, subdomain are same for both cases.
can anyone help me how to solve this error
i am new to this COMSOL and with the help some tutorial i learned how to use. i am much familiour with Matlab.
i want to ask 1 question, which i am facing in my most of the models.
let me excplain you how i make model and use. may be i am doing some mistake there.
1) i made my model in MATLAB using COMSOL functions .
2) Then i load it COMSOL using file -> import -> Geometry objects. assign sub domain and boundary conditions. choose solver if required and save the model in (.m) MATLAB file.
using this Matlab code i assign different conductivity and permitivity with other same boundary conditions.
till here its working fine,
now when i made one big cylinder C1 with the radius of 0.5 cm and cylinder C2 with the radius of 0.05 cm. apply step (2).
now in the MATLAB code if i change the radius of C2 0.1 cm i gives me error
??? Error using ==> fem2jxfem at 60
Errors found in FEM structure.
Error in ==> multiphysics at 81
jxfem=fem2jxfem(fem,femname(inputname(1),fem),{'lib'},false,false);
i checked the no of boundary, subdomain are same for both cases.
can anyone help me how to solve this error
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Modifying the Fluid Flow Equation System
Hi everybody,
Is it possible to change the fluid flow equation system in order to fit a logarithmic function in the derivative? I am currently using the earth science module to model a dual porosity fluid flow system. However, my numerical model requires me to have the derivative of a logarithmic function of pressure as opposed to just a pressure time dertivative. In other words I have
d(ln(p))/dt instead of d(p)/dt
where p is pressure and t is time. As far as I know, it is possible to change all terms of the equation system except for the derivative term. Any advice?
Thanks and Best Regards,
Andres Bracho.
Is it possible to change the fluid flow equation system in order to fit a logarithmic function in the derivative? I am currently using the earth science module to model a dual porosity fluid flow system. However, my numerical model requires me to have the derivative of a logarithmic function of pressure as opposed to just a pressure time dertivative. In other words I have
d(ln(p))/dt instead of d(p)/dt
where p is pressure and t is time. As far as I know, it is possible to change all terms of the equation system except for the derivative term. Any advice?
Thanks and Best Regards,
Andres Bracho.
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heat source setting
HI;I have a question that when I using heat transfer in solid and lamina flow model to simulate heating a crucible in a silicon furnace, when I setting the heat souce desity equal:6000W/m^3, the simulation is coveraged, The mamxium temperature is 1400K, but when the value is 20000W/m^3, the simumation divergenced. pls help me! How can I solve this question.Thanks.
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Indetity pairs should be fixed?
hello
I am running a static structural mechanics problem on comsol multiphysics 3.5 . I have a building and i want to see the effect of a seismic load on my structure ..
My problem is that the building is an assembly of masonry walls and wooden floors , so i have to set identity pairs between them .... I want to ask , when we create identity pairs , we should set that these pairs are fixed?
I am running a static structural mechanics problem on comsol multiphysics 3.5 . I have a building and i want to see the effect of a seismic load on my structure ..
My problem is that the building is an assembly of masonry walls and wooden floors , so i have to set identity pairs between them .... I want to ask , when we create identity pairs , we should set that these pairs are fixed?
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