Questions tagged [simulation]
Simulation is the process of mimicking the behaviour of a real physical process or system using a representative model.
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Simulate Jump-Diffusion $dX_t = \mu(X_t)dt + \sigma(X_t)dW(t) + \int_{\{|c| <1 \}}g(X_t,c)\tilde{N}(dt,dc) + \int_{\{|c| \ge 1 \}}h(X_t,c)N(dt,dc)$
I would like to be able to model an SDE having the form
$$dX_t = \mu(X_t)dt + \sigma(X_t)dW(t) + \int_{\{|c| <1 \}}g(X_t,c)\tilde{N}(dt,dc) + \int_{\{|c| \ge 1 \}}h(X_t,c)N(dt,dc).$$
where $W$ is a ...
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Why not use the convolution theorem for explicit timestepping?
Consider the advection equation
\begin{equation}
\frac{\partial C}{\partial t} + u\frac{\partial C}{\partial x} + v\frac{\partial C}{\partial y} = 0
\end{equation}
I want to do a forward time, center ...
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Beam propogation method for a waveguide. How to get single mode?
I am simulating a waveguide using diffractio python library (https://diffractio.readthedocs.io/en/latest/readme.html). The idea is to create a single mode waveguide using wave propogation method.
...
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How to implement large rotations in total lagrangian formulation (nonlinear FEM)?
I have developed an Octave script to solve the nonlinear Euler-Bernoulli beam equations with linearized von Karman-strains, i.e. higher-order terms are dropped. The simulation results agree with ...
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Can I build an electrostatic simulation of conductive objects using just the method of images?
I wish to build a simulation of self-assembling wires. Think lots of ball bearings in a 20KV electric field and they form emergent structures.
If I use the method of images to figure out what the ...
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Is a 2021 MacBook Air sufficient for modeling and simulations research in fluid dynamics?
I code mostly in Matlab, simulating various simple fluid dynamics models.
One particular simulation has the potential to become sort of complex, though I believe the set of coupled equations will ...
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Solving Kepler's Equation with Newton-Raphson Method
Note (2022/03/07): This question is solved. Unfortunately, I'm not able to accept the correct answer by Lutz Lehmann, because I screwed up my registration and the account which posted this question is ...
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What's the relationship of machine learning and mechanical simulation?
What's the relationship of machine learning and mechanical simulation?
Particularly, machine learning is about learning from a large sample and predicting based on filters tuned on that.
Mechanical ...
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Feasibility of synthetic, simulated predictions w/o matching against empirical physical measurement?
Feasibility of synthetic, simulated predictions w/o matching against empirical physical measurement?
This has puzzled me lately.
So, while it's sometimes common to approach modelling and model ...
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Any literature that extensively discusses the ability to strongly inter-/extrapolate computationally on little empirical data?
Any literature that extensively discusses the ability to strongly inter-/extrapolate computationally on little empirical data?
This topic has fascinated me, but I find that it seems a bit novel.
...
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How are consistency constraints maintained in Circuit Simulation?
I have always taken for granted circuit simulators and I didn't spend time understanding now. I wish to understand better now.
Normally when you forward simulate ODE systems there is a single dynamic ...
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FEM : energy minimization VS PDE solving
Engineering FEM
When I studied engineering, I learned the traditional approach for finite elements for elasticity. The point was to solve the PDE $-div(\sigma)=f$ as:
Multiply your PDE with a test ...
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Type of computer used for computation
In some scientific papers I see that authors provide what type of simulation tool and what type of computer was used for computation. For example:
The computations were performed using MATLAB in ...
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Identifying an unknown P.D.E. from solution data
I have a black-box simulation that produces the time evolution of a probability density function p(x, t) in 1 dimension from arbitrary initial conditions p(x, 0). The underlying simulation occurs on a ...
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Can someone help or point me out to C++ source code for a two body orbit simulation using symplectic integration?
I've professional experience with physics simulations and C++ programming, although
I don't have specific experience with astrophysics simulations.
I'm trying to build a two-body evolving system ...
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Procedure to convert continuous equations of motion to discrete version
Let's take a mobile robot and suppose we know its continuous equations of motion, for example this car-like simple model.
Now if I am simulating this robot in a continuous 2D plane, then coding the ...
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Reproducing a paper's result for Topological Insulators
For the past weeks I have been trying to reproduce Agarwala's results but I've been unsuccessful. From this paper I am trying to reproduce the first and last columns of Fig.2, by implementing eq.2; ...
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In a random walk simulation, how do I get the mean and standard deviation of how many times the walk returns to the origin?
So I'm simulating a 1-dimensional random walk, with 1000 walks that each take 1000 steps.
How do I calculate the average number of times that a walker returns to the origin and then the standard ...
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How to reduce computational time in DDE simulation on Matlab
I need to simulate a network of nodes. The weights of the edges are being given in a matrix . Due to the non-zero distances between the nodes, we consider time-delays, which are computed given the ...
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N-body problem with differents solvers (RK2, RK4, Euler symplectic, Stormer-Verlet) : planets drift to infinity
I'm trying to write an integrator for the 2 and 3-body problem. I choose to start from a generalisation to N-body problem so I can just pass my bodies to the same integrator in the two cases.
I'm ...
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Solving Cahn-Hilliard equation using semi-implicit Fourier spectral methods
So, I have written both a C and python code to solve the 2D Cahn-Hilliard equation:
\begin{equation}
\frac{\partial c}{\partial t} = \nabla^2\left(c^3 - c - \kappa\nabla^2c\right)
\end{equation}
...
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Large scale nonsymmetric eigenvalue problems in practical applications
I am trying to determine need for solving large scale nonsymmetric eigenvalue problems in both industry and academia.
I am interested in any kind of problem where we cannot assume that matrices are ...
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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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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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How to make a time-parametrization slower around a point but not too slow?
For animation purposes (see below) I need to use a parametrization which 'slows down' near a specific value;
More precisely, I am looking for a 'nice' monotonically increasing function $r:[0,1] \to [...
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Finite element analysis software for acoustic and electrostatic
I need to do a simulation for my thesis project involving some piezoelectric nanoparticles in a fluid beamed with ultrasounds. I'm looking for a software for such simulation and for now it seems me ...
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588
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Projectile Motion Simulation with Aerodynamics using Euler's Method
I'm trying to simulate the motion of a projectile taking into account aerodynamic drag. The code works perfectly if the aerodynamic drag is zero. However, if the drag coefficient or velocity is too ...
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Numerical stability of taking the `mean` of outputs from the simulation of a discrete stochastic dynamical system
I am writing a simulation for a discrete stochastic dynamical system. Since the simulation is stochastic, I need to run the simulation multiple times and then average the values of each timestep. I ...
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Why is perfect sampling not used in large-scale lattice model simulations?
The statistical physics literature is replete with papers describing simulations of lattice models, such as the Ising model. Typically, these are done through Monte Carlo methods, such as the ...
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Conserve energy by message passing?
There are $N$ particles with positions $x_i(t)$ and velocities $v_i(t)$ and mass 1. There is a potential function $U_{i,j}(x_i, x_j)$ between each pair of particles, which is $0$ unless the particles ...
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Choosing an appropriate time step for a discrete & continuous dynamics simulation
I have inherited of a flight dynamics simulation in C++ which represents a small drone with it's autopilot, actuator dynamics and a solid state IMU.
Hence, it is composed of a few models, some ...
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computing time scale and steady state concentration in microfluidic channels
I have been performing convection-diffusion transport studies on microfluidic channels like the following
The inlet concentration is specific and I obtain the time-dependent concentration profiles of ...
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Problems with simulation of a spatial filter 4f setup (Python)
I have a question about my code which computes numerically the output field of a 4f setup with a pinhole in the middle which works as a spatial filter.
My setup consists of two lenses with 50mm focal ...
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Extracting data from VTK simulations using C++
I have been given a few numerical simulations regarding fluid mixing and have been asked to extract a few parameters from them using C++. Altogether there are about 1000 VTK files per simulation, and ...
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Is the Immersed Boundary (IB) method a Direct Numerical Simulation?
Is the Immersed Boundary (IB) method considered a Direct Numerical Simulation?
A DNS code is the most detailed type of simulation and the most accurate but computationally expensive, right?
What makes ...
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Discretization formula for a system of two differential equations. "Solution to one of these is the initial condition of the other". In which sense?
Consider the following stochastic differential equation
\begin{equation}
dy=\left(A-\left(A+B\right)y\right)dt+C\sqrt{y\left(1-y\right)}dW\tag{1}
\end{equation}
where $A$, $B$ and $C$ are parameters ...
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Reading VTK file into C++ for analysis
I apologize in advance if this post is at all ignorant or elementary, I am a pure mathematician who is newly getting into the world of scientific computing.
For my research, my advisor would like me ...
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Artificial Intelligence, Modeling and Simulation
Artificial Intelligence (AI) and its subsets i.e. Deep Learning (DL), Machine Learning (ML) etc. are becoming more and more ubiquitous in engineering, technology and science. Modeling and Simulation (...
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What kind of a researcher am I?
So far, I've worked a bit in modeling, simulations and simple lab experiments, and I've really enjoyed all three research methods to approach a single research question. I can write tricky (in terms ...
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How to visualize the vorticity / flow for a rigid body moving through a fluid?
How can I write down two-dimensional Navier-Stokes equations for a simple rigid object immersed in a flow and freely falling due to gravity? I'm trying to view the vorticity that's induced by the ...
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Tackling multiscale problem in numerical simulation
In a dusty plasma system there are more than one component with different masses, i.e, electrons, ions,neutrals and dust grains. Accordingly, there are more than one temporal and spatial scales ...
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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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How to get free energy surface of a 3d Ising Spin system using Monte Carlo simulation?
I am doing a Monte Carlo Simulation of the properties of a 3D Ising Spin system. I want to get the free energy surface of the spin system from the simulation. It is a magnetization vs free energy ...
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Stress during unloading in FEM simulation of an elasto-plastic truss element
I am simulating the behaviour of a single bar composed of two node points by fixing one point and applying a force on the oder node with $F_x = 1$ and fixing $u_y=0$. I am assuming the material to ...
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Decoupling of the fluid viscosity and incompressibility constraint in a partitioned scheme
I am new here and this is my very first question: I hope I respect all the criteria and rules.
I am just getting started with partitioned approaches for solving FSI problems. I am interested in a ...
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What are the alternatives for ABAQUS in generating an *.inp file from a CAD model
ABAQUS gives a .inp file (in pre-processing stage) where the information with regard to the preprocessed model is defined, information such as geometry, mesh type, number of elements, boundary ...
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How to simulate over 1 billion particles?
I want to simulate human erythrocytes in capillaries. I calculated, that for a 1 meter long and 1 mm in diameter capillary there are about 3 billion blood cells.
Erythrocytes are actually discs, but ...
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Can one publish a new model and simulation without physical experiments?
When I read strong papers from, say, the Journal of Fluid Mechanics, a simple model, simulations and physical experimental results are given, showing good agreement.
Can one publish a new model and ...
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Conserving Energy in Physics Simulation with imperfect Numerical Solver
I am creating a C++ Physics Simulation where I need to move an rigid body through an acting force field.
Problem: simulation does not conserve energy.
Quesiton: abstractly, how is conservation of ...
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Processing time steps in chunks with Fortran [closed]
My PDE simulation program written in Fortran has to make about 2 million variable time steps. But with each time step it slows down more and more, so that if it initially makes 1000 time steps per ...
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