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Questions tagged [electromagnetism]

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For questions about modeling phenomena related to electromagnetic fields.

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2D axisymmetric Magnetostatics Finite Element Method solver

I am new to the field of magnetostatics. I wish to write a 2D finite element code for obtaining the magnetic field inside a solenoid coil. I have started with a 2D code and have followed the method as ...
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40 views

Digital beamforming: how payload manipulation can change beam direction without manipulating the carrier?

I'm interested in how digital beamforming works and I can not find an answer for a lot of time. I googled, asked teammates, and couldn't get it. Let me describe my question. From my understanding, the ...
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33 views

Biot-savart numerical integration

I have a mesh structure of tetrahedrals and I know the current density on each node. I want to evaluate the magnetic flux density. Therefore, I use Gaussian quadrature. However, I do not know how to ...
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43 views

Plotting the motion of a positive charge in a cylindrically symmetric magnetic field

I want to plot the motion of a positive charge in a cylindrically symmetric magnetic field. I am assuming a cylinder around the z-axis, with the magnetic field going in clockwise direction. The B-...
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1answer
65 views

How to Calculate magnetic and electric field in 2D Magnetotelluric using Edge based Finite Element

I calculate 2D Model of Magnetotelluric responses which are apparent resistivity and phase. I do the calculation for Transverse Electric (TE) mode. Then I used edge based finite element with ...
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1answer
166 views

Using ODE to plot particle-motion with scipy.integrate.solve_ivp

My Problem: A positively charged particle (mass = 2 * 10-27 kg) is moving along the x-axis. It is travelling in a homogenous magnetic field such that the field axis in z-direction. The energy of the ...
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1answer
162 views

Weak Formulation of Poisson's Equation for Electrostatics with Surface Charge

I am currently attempting to use FEnICS to solve an electrostatic problem with two materials of different permittivity $\varepsilon_1$ and $\varepsilon_2$ forming an interface: Consider a domain $\...
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2answers
168 views

How to create a good preconditioner for a system of linear equations that is created with FEM applied on the time harming Maxwell eqution?

I set out to solve the time harmonic Maxwell equation numerically which was discritzed using FEM and with the use of Nedelec elements as basis and test functions. The equation reads: $$ \nabla \times \...
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23 views

Why does this Non-Standard FDTD implementation lead to infinite increase in the magnitude of an EM pulse?

I have been working on a Particle-In-Cell Framework in Python and have noticed an issue where the magnitude of a EM pulse increasing infinitely as the simulation updates. Currently, I am using the Non-...
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74 views

FEM port Boundary definition for electromagnetics and wave guides

We are currently in the process of implementing ports in our EM FEM simulation SW. We have come across the definition of boundary conditions for the ports, and we do not understand the equation for ...
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1answer
156 views

Finite element method for high-frequency electromagnetics

I am writing a project about the Finite element method for use in high-frequency solutions of Maxwell's equations. This could be for use in antenna design and similar. I have some trouble ...
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44 views

Results blow up when number of intervals is increases (Yee algorithm FDTD, dielectric sphere)

I have been trying to write a program that analyses EM wave scattering by a dielectric sphere for a project. The reference is Sadiku's book Numerical Methods in electromagnetics Edition 3. Now the ...
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38 views

Calculating magnetic flux density

I have a geometry where current density distribution is constant. I can calculate the $z$ component of magnetic flux density according to Biot-Savart law as following: $$B_z(x,y,z) = \int\limits_x\int\...
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85 views

Numerical dispersion in FDTD

I was reading the book "Computational Electrodynamics: The FDTD method" by Taflove and Hagness, probably the most cited book when it comes to the FDTD method in Electromagnetics. In the ...
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1answer
78 views

Electrostatic Force - Simulate Trajectory of Test Particle using Runge Kutta - Force always Repels

In the center of a 2D-Plane a positive static charge Q is placed with position r_prime. This charge creates a static electrical Field E. Now i want to place a test particle with charge Q and position ...
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105 views

Numerical simulation of magnetic dipole in a inhomogeneous magnetic field

Goal: I want to use Python to illustrate how a magnetic dipole with magnetic moment m2 moves in a non-homogeneous magnetic field in a 2D-Plane. This field is generated by another magnetic dipole with ...
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104 views

Why does FDTD and FIT disregard Gauss's law?

This is a reformulation of a question I asked a couple of days ago. I'm posting it again because I believe the previous post was very unclear, I will probably delete the previous question. My question ...
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1answer
95 views

plotting $F=K \frac{q_1 q_2}{r^3}$ in python

I tryin to plot the position of electron in the hidrogen atom by Coulomb's law, $F=K \frac{q_1 q_2}{r^3}$ This is mi code ...
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104 views

A Question About a Claim from 1991 Computational EM paper about the Cancellation of certain Boundary Terms

Please let me know if this is not the appropriate site for this question. I found questions regarding EFIE/MFIE/CFIE on this site, so I thought my question might fit. I am studying the paper by Putnam ...
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1answer
148 views

Help with modified bessel functions

I'm trying to parse the following expression (Eq. 35 in The Magnetic Field in the Vicinity of Parallel and Twisted Three-Wire Cable Carrying Balanced Three-Phased Current) in Python and calculate its ...
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58 views

How can I improve the accuracy of the calculation of the magnetic field in Gmsh/GetDP?

I need to calculate the magnetic field along a straight line in proximity of an array of 6 magnets. I used the tutorial files "magnets" included in Gmsh and I slightly modified the file in ...
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107 views

How to use FEniCS to calculate the electric field of an isolated charged sphere

Initially I thought that this is the kind of question which ought to have already been answered in the form of an example online, but so far I haven't found one. I will admit that I am very new to ...
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73 views

How to calculate the interior value of triangular element in edge (vector) finite element?

I was using an edge (vector) finite element to solve electromagnetic diffusion (two-dimensional cases). The element that I used was a triangular element. I have got the result of the finite element in ...
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237 views

More efficient way to calculate magnetic field using Biot-Savart

I am writing a program in python that is supposed to calculate the magnetic field along a conducting coil that is made up of a bunch of points, and the magnetic field is generated by other conducting ...
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1answer
83 views

Simple reference problems for time harmonic Maxwell equations

For Navier-Stokes problems we can often choose a relatively simple verification problem such as the lid driven cavity, flow over a cylinder, or flow over a backward facing step to verify our ...
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76 views

Numerical scheme to calculate the normal mode of a set of hyperbolic PDEs?

I would like to solve the linearised, ideal, MHD equations, where the gas pressure is zero. $$\frac{\partial u_x}{\partial t}=v_A^2(x,z)\left[\nabla_{||}b_x - \frac{\partial b_{||}}{\partial x}\right],...
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1answer
1k views

Finite difference methods in cylindrical and spherical co-ordinate systems

I am quite familiar with finite difference schemes in cartesian coordinates. The key point here is that every point in the cartesian grid is treated equally as the spacing between consecutive points ...
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80 views

COMSOL Circularl polarization

I'm having some problems trying to implement circularly polarized light in COMSOL Muliphysics. For a isotropic homogenous media, I've obtained without problems the TE and TM reflectance curves. ...
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2answers
627 views

Kronecker product representation of the finite difference laplacian

The laplacian equation when discretized gives a system of linear equations that can then be solved. See the answer to this question: https://math.stackexchange.com/questions/3120948/discretization-...
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47 views

Discretisation by FVM with triangulare mesh

I work on electromagnetic modeling, and I use the finite volume method as a tool, so I want to develop code by the modified finite volume method (with triangular mesh), my problem studied is in a ...
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1answer
339 views

Simple particle-in-cell examples

I am studying about the 1D EM-PIC (Electro Magnetics using particle-in-cell) simulation. I want to have a simultaneous time-integration of the electric/magnetic fields plus the motion of free charges ...
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61 views

Spectral solver on em-pic

I'm recently studying for the spectral solver to implement EM-PIC code. I read an article and have some questions. Many PIC codes uses spectral solver to overcome numerical artifacts on FDTD. In the ...
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3answers
541 views

Minimum number of elements (mesh size) for electromagnetic simulation

Does someone have a reference for the minimum number of elements (or maximum mesh size) for electromagnetic simulations where a mathematical or numerical explanation is given? I have found several ...
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277 views

Parallel plate capacitor as simple superposition of Coulomb-fields

I am trying to calculate and visualize the electric field inside and outside of a parallel plate capacitor by assuming a uniform distribution of point charges on each plate and by adding up the ...
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1answer
228 views

MATLAB's ode45 not dealing with initial conditions well [RESOLVED]

*Concern highlighted in yellow *Solution at bottom I have a differential equation to solve for the motion of an electron: $$ \frac{d^2v}{dt^2} = \frac{1}{\gamma^6}\left( \frac{eE}{\tau m} - \left( \...
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1answer
60 views

Is there any method to incorporate minor changes into solved meshes to speed convergence in particle-in-cell solvers?

Apologies for the terrible title. I'm trying to perform a 10^6 timestep electrostatic particle-in-cell simulation on a rather large mesh, with very limited computational resources (a single GPU). ...
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0answers
98 views

FEniCS implementation of Maxwell equations for a dipole antenna

someone knows where I can find a FEniCS implementation of Maxwell equations for a dipole or other type of antenna? I mean a dipole antenna with an arbitrary geometry of every 'leg' in the dipole.
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41 views

Multipole expansion for magneticfield intesity (magnetization)

I'm using the Barnes Hut method to calculate the magnetic vector potential induced by an applied current. Given as: $\begin{equation} A(r) = \frac{\mu_0}{4\pi} \int_V\frac{\bf{J(r')}}{|r-r'|}dV(r') \...
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2answers
1k views

Electromagnetism FEM (FEniCS) interpolation - leakage effect

As for the background of what is going on: I'm using FEniCS that is dedicated FEM solver The problem I'm solving is magnetostatic problem where the governing PDE is $$ \bf{\nabla} \times \frac{1}{\mu}...
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2answers
1k views

Graphing electric potential of a ring of charge using MATLAB help

Here is a summary of what I am trying to do: Use MATLAB to compute the potential $V$ at any point $(x, y, z)$ in space due to a uniform ring of charge. Use a Riemann sum to compute the integral ...
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1answer
92 views

Demagnetizing field using scalar potential method

I want to calculate the stray magnetic field from a ferromagnet using the scalar potential method (1). The problem consists of a ferromagnetic cuboid divided into small cuboidal cells in which the ...
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1answer
69 views

Simulating magnetic particles in a field free point generated by two opposing magnets

This is probably a long shot with such a short time, but I've been trying to get theoretical data for a project I'm working on. The project involves using a very simplified version of magnetic ...
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1answer
303 views

TMZ TME modes, clarification

I'm refering here to Taflove's "computational electrodynamcis, 3rd ed." He says Let us assume that the structure being modeled extends to infinity in the z-direction with no change in the shape ...
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0answers
46 views

Open source multiphysics software that can model the interaction of two insulators with a user-specified electrical force law?

Given two solid bodies of masses $m_1$ and $m_2$ with invariable charge distributions $\rho_1(\mathbf{r_1})$ and $\rho_2(\mathbf{r_2})$ in them,* respectively, I would like to model the electrical ...
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1answer
174 views

Average value divergence in spectral method for Poisson equation

I'd like to know how to deal with a divergence when trying to solve the Poisson equation for electrostatics with a simple spectral method. I'm not sure how to best state my problem, so I'll explain ...
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0answers
111 views

Solving electrostatics Poisson equation with Intel MKL routines

I am trying to solve the 3D Poisson equation $$\nabla\cdot(\epsilon(\mathbf{r})\nabla) u(\mathbf{r}) = f(\mathbf{r})$$ I notice intel advertises routines that appear to solve $$\nabla^2u(\mathbf{r}...
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1answer
722 views

Poincare map for Arnold-Beltrami-Childress Magnetic Field in Python

I want to plot the Poincare map for Arnold-Beltrami-Childress magnetic field for parameters $A=1, B=0.816, C=0.5773$ in Python for the Poincare section $z=0$. Also, I am not able to understand what ...
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1answer
144 views

Magnetization Vector from XY Model for an AntiFerromagnetic System

I am working on an XY model and I'm trying to calculate the magnetization and direction for an anti-ferromagnetic (AF) system. So I have a collection of spins in the $XY$ plane represented as vectors ...
2
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1answer
141 views

Calculation of the EFIE integral

I need help computing the following integral: $$ \int_{}\frac{(1+jk|\vec{r}-\vec{r}^\prime|)e^{-jk|\vec{r}-\vec{r}^\prime|}}{|\vec{r}-\vec{r}^\prime|}d\vec{r}^\prime $$ in this integral $\vec{r}$ ...
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59 views

Magnetostatic modelling Radia: Increasing distance between magnets a produces positive force until a certain point, beyond which force goes haywire

I have two sets of magnets. One set consists of two electromagnets (Shown below: Blue) and the other set consists of two NdFeB N40 permanent magnets. Both sets of magnets lie on the same plane. I want ...

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