# 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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475 views

### Why not use the convolution theorem for explicit timestepping?

Consider the advection equation $$\frac{\partial C}{\partial t} + u\frac{\partial C}{\partial x} + v\frac{\partial C}{\partial y} = 0$$ I want to do a forward time, center ...
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1 vote
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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. ...
103 views

### 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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1 vote
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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 ...
100 views

### 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 ...
168 views

### 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 ...
68 views

### 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 ...
• 379
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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 ...
• 41
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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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1 vote
38 views

### 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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1 vote
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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; ...
143 views

### 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 ...
429 views

### 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 ...
292 views

### 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: $$\frac{\partial c}{\partial t} = \nabla^2\left(c^3 - c - \kappa\nabla^2c\right)$$ ...
100 views

### 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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1 vote
106 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 ...
149 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 ...
1 vote
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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 ...
1 vote
483 views

### 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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1 vote
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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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210 views

### 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 ...