warning: low minimum element quality
hi everyone, i keep getting a warning that says that the minimum element quality is low ... my sim runs but i get a crappy diffusion profile .. what to do and does this minimum element quality IS what...
View Articleprob plot of dependant variables Rtol and Atol ?
hi, for time-dependent study, fully coupled solver, is it possible to plot (similar to convergence plot) the relative tolerance and the absolute tolerance for each one of the used (simulated) dependent...
View ArticleFailed to find consistent initial values
Dear COMSOL users! I am trying to model wormhole formation during the acid injection in the reservoir. It is two scale model: Darcy scale and pore scale. I am using 3 physics: Darcy law, transport of...
View Articleerror
I try to do as photodiode 3D simulation model is two-dimensional. But I encounter the following error: Undefined value found. - Detail: Undefined value found in the equation residual vector. There are...
View Articlesolution results and iterations number
Hi, I am running time-dependent model fully copuled with termination techniques set to iteration and tolerance. I see under progress that the nonlinear solver reaches ~100% with the last iteration...
View ArticleCompute study for only the 2D cross section of a 3D geometry?
Hi all, I have made a 3D model in COMSOL vs 5.2a of a microfluidics channel and am attempting to model the DEP response of cells in the channel to the presence of an electric field created by...
View ArticleHow to define the boundary conditions for oscillatory flow in COMSOL?
Hi I want to model an oscillatory flow passing fins inside a resonator. I need to define both of the velocity and pressure boundary conditions at the inlet (x1) and the outlet (x2) of the computational...
View ArticleModules
Hi, New to using COMSOL, basically I want to develop a PEMFC but do not have the batteries and fuel cell module. Is there anyway the user can manually put in equations etc? Also for analysis I want to...
View Articleweak constraint or pointwise constraint
Hello, I would like to have ur opinion for this situation: I wish to constraint the (fluctuating) pressure to an average value of 20 [constraint expression: aveop1(p)-20] at the inlet boundary while...
View ArticleFloating conductors with fixed potential difference
Hi, I'm trying to model a conductive instrument placed in an electric field (I'm interested in the electric field flux through a few boundaries of the instrument). To model this conductor, I've applied...
View ArticleTime-discrete solver
Using the Weak-Form PDE interface and the time discrete solver, I am trying to implement a pressure-correction scheme for the Stokes Problem. Since this requires three previous solutions (time steps) I...
View Articleheat transfer with solid mechanics problem
I build a model with heat transfer in solids and solid mechanics, heating from the bottom of the model by adding a high temperature. There's a boundary load set on the top side. To simplify the...
View ArticleFinding Photonic Bandgap Curve
Hi, I am trying to model a photonic crystal fiber to exihibit photonic bandgap. But i don't know how to get the PBG curve. Can anyone help me plz? I also want to know how to operate multiple wavelength...
View ArticleSmall time step & slow solving process
Hi I'm building a 2D, time dependent model relating to Solid Mechanics/Heat Transfer in Solids/Coefficient Form PDE. They are coupled by the thermal expansion and swelling of the solid. The creep...
View Articlelog and failure
hi Everyone, i'm simulating a diffusion through a mask and my simulation does not fail (although the convergence keeps going up and down in a strange fashion) BUT i have the NFail in the log rising, it...
View ArticleIntegral over a disk in different positions
Hi! I have computed a magnetic field in a region of space and have defined a disk inside that region. I would like to compute the energy in the disk, which involves integrating the magnetic field, for...
View ArticleWhat is "Maximum Element growth rate" and "curvature factor" in the Mesh...
Under "Mesh" node and then under "size" , I see a section named "Element size parameters". Inside it there is this "Maximum Element growth rate" and "curvature factor" that Comsol always automotically...
View ArticleLong wire simulation
Hello, I'm very new to COMSOL Multiphysics 5.2a I would like to create long (5 m) and thin ( d = 30 micrometers) tungsten wire sagging in the gravitational field, having electric potential 1800 V with...
View ArticleUnit syntax error, not sure why
This is likely something very obvious but I can't figure it out. I'm trying to define a variable: omega0 = e_const*hbar_const*sqrt(fermienergy/W) fermienergy has units joules and W has units of...
View Articlemodifyin mesh didn't modify my results
Hi, I have modified my mesh in order to choose the appropriate one for my next simulations, however i have got the same result for extremely fine as for normal mesh. I'm looking for different values of...
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