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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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How to add damped constraint force to constrained dynamics simulation?

I have implemented a constraint dynamics physics simulation as proposed by Andrew Witkin et al 1990, but I cannot get the initial constraint "snapping" correctly. I implemented $$ JWJ^{T} \...
EmmanuelMess's user avatar
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Advanced computing on FPGA

I am an absolute beginner in the FPGA topic (so far I have only implemented a couple of simple logic gates in Verilog and simulated them in ModelSim). I studied digital electronics, logic elements, ...
ayr's user avatar
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Why is Magnetic Susceptibility not showing the expected transition in 2D&3D Ising Model?

I'm trying to code the Ising Model with the metropolis algorithm to study the ferromagnetic-paramagnetic transitions. The code seems to work ; the equilibration happens. While equilibrating, the ...
SSsaha's user avatar
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Would a Co-simulation orchestrator work when a model uses a variable step size integrator

In every paper i was able to find, detailling the process of writing a co-simulation orchestrator (either Jacobi or Gauss-siedel), the paper assumed that both models were to compute their outputs on ...
J.M's user avatar
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Synchronous integration vs asynchronous integration in simulations with complex problems

Lets say i want to create a detailed simulation of a complex system. For instance a drone. This simulation will have to contain a few models, each one with it's own requirements, for instance A 6Dof ...
J.M's user avatar
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Calculating a 2D Ewald sum for a multipolar expansion

I am attempting to calculate the potential of a particle at the center of an infinite two-dimensional lattice as per the following reference: Reference: Lambin, PH & Senet, P. Ewald Summation of ...
JasonC's user avatar
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How can I compute the longest relaxation time?

Cross-posted on Stats.SE and on MMSE. In the case of Monte Carlo simulations: Autocorrelation Time ($\tau_{\text{int}}$): A measure of how many steps are needed for the correlations in the chain to ...
user366312's user avatar
2 votes
1 answer
418 views

How to leverage the GPU for parallel 3-body problem computations

I have a 3-body simulation which must run millions of times. As far as I know, the GPU shines when it gets to preform simple operations on huge matrices/arrays. Currently I'm debugging and running my ...
Remeraze's user avatar
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102 views

Can I reduce my simulation error with a staggered grid, postprocessing and compatibility equation feedback?

What I did Using the finite difference method, I solved with a certain amount of error the following system of hyperbolic partial differential equations in cylindrical coordinates (the problem is ...
FriendlyNeighborhoodEngineer's user avatar
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2nd-order backward difference approximation for temporal terms of Euler–Bernoulli beam

I am trying to solve the Euler–Bernoulli beam numerically in structural dynamics analysis: $$\frac{\partial^2w(x,t)}{\partial t^2}= \frac {q(x,t)}{\mu(x)}-\frac {1}{\mu(x)}\frac {\partial^2}{\partial ...
Chaozhi Qiu's user avatar
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Determining Stainless Steel Pipe Length for Heat Transfer to Reach 1000°C

I'm working on a Uni project where I need to determine the length of a stainless steel pipe that is required to heat a fluid up to 1000°C. The pipe will be placed in an oven that can reach up to 1400°...
Apo's user avatar
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How do we calculate solvent accessible surface area (SASA) for a system simulated with annealing protocols in Gromacs?

I calculated SASA for 4 systems using the following command. The trajectory file (run.xtc) is not treated with gmx trjconv option. In my MD simulation, I followed two annealing cycles in each 50 ns ...
Ema 's user avatar
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Simulating a dataset from model output when model includes multiple binary deviation-coded variables

I am trying to simulate data using parameters from a glmer() model output. The model, which comes from a published paper, is as follows: DV ~ 1 + group* sex *verb type + trial number + (1 |participant)...
HungryHippo's user avatar
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Softening vs Smoothing Length... Is There a Difference?

I have a simple questions on terminology. Is there a difference between softening length and smoothing length? I have been using the 2 terms interchangeably as the minimum distance between particles ...
dcro's user avatar
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1 answer
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Why does a two-body simulation result in no change of the y-component?

I've been attempting to create a model of a heliocentric orbit based on Newton's law of gravitation: $$ \frac{d^2 \vec r}{dt^2} = -\frac{GM}{|r|^2} \hat r $$ This is what I have so far: ...
JS4137's user avatar
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Calculating Madelung constant via Ewald summation

I am attempting to calculate the Madelung constant for NaCl using an Ewald sum derived by Nijboer. There are other methods and published codes to do this, but I am specifically interested in working ...
JasonC's user avatar
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2 answers
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Starting configuration for Molecular Dynamics

I have to build a bilayer using a structure obtained in a previous MD simulation. In the structure, some chains of the molecules cross the simulation box as shown below. I added water layers to the ...
Ema 's user avatar
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2 votes
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In electromagnetic simulation, how much does the feed model impact an antenna's directivity performance and E-field phase readings?

Question: How much would a simplified feed model in an EM simulation alter an antenna's directivity and the E-field phase reading when compared to using a more complicated/realistic feed model? I am ...
Xingda Chen's user avatar
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1 answer
91 views

Modeling Homeostatic Regulation with Python: How to Simulate Dynamic Systems

Hello Computational Science community, I am working on modeling a dynamic system that involves homeostatic regulation in Python and I could use some guidance on how to implement it. Here's a brief ...
tanya singhal's user avatar
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155 views

Damping not working in Verlet simulation with absolute constraint

I'm trying to build a simple physic simulation with Verlet intergration, which I'm currently implementing as such: ...
silverfox's user avatar
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1 answer
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Deformation matrix, Math hack for stability on large simulation steps?

So there is a numeric technique for updating a deformation gradient in MPM that goes as: $$F_{n+1} = (I + \nabla \vec v \Delta t)F_n$$ This works for small time steps but for large time steps ...
Makogan's user avatar
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1 vote
1 answer
92 views

Improved euler on hybrid methods where both time and space are discretized?

I am trying to understand how to use the improved euler method on MPM simulations. In the kind of MPM simulation I am doing with forward euler the order of operations is as follows: Write particle ...
Makogan's user avatar
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3 votes
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112 views

Verlet integration on grids or how to get better stability in hyperelastic simulation

I am using MLS-MPM to simulate both solid and fluids. It works, but the amount of time steps I must do for hyperelastic solids is absurd. To give you some perspective, I am able to simulate just the ...
Makogan's user avatar
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Professional orbital simulation software methods, accuracy, runtime

I'm working on an orbital body simulation as a personal project. I understand that it's not going to be as good as professional software, but I'm wondering what contemporary, general purpose, ...
Indrada's user avatar
2 votes
0 answers
114 views

How to calculate the change in water level height after each step in a water displacement simulation?

I'm trying to write a very simple simulation of volume/water displacement. Every timestep a sphere gets lowered a bit further into a cylindrical container filled with water. While the physics behind ...
Johann Gruber's user avatar
1 vote
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49 views

Monte Carlo simulation of classical Heisenberg model doesn't represent Curie curve

I've created a JavaScript file to execute and log average energy and magnetization values of 2D lattice classical Heisenberg model. I run the simulation with parameters, ...
M. Çağlar TUFAN's user avatar
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I encountered some issues simulating the shape transition of silicon clusters using LAMMPS

== I have been trying to write an input file for lammps to simulate the shape transition of a nanoparticle of silicon using multiple potentials to obtain the best structure, which I will compare with ...
Hadjmohammad Abderahmane's user avatar
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Energy potential involvign pressure and viscoscity?

Making a really long explanation short. I am looking for an energy density function for an incompressible isotropic fluid that involves both viscoscity and pressure. The reason is, there is a way to ...
Makogan's user avatar
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0 answers
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Solving a minimization problem without flattening inputs?

I am reading this paper on improving time steps for solving simulation problems: https://www.math.ucla.edu/~jteran/papers/GSSJT15.pdf The authors developed this energy function: $$E(x) = \frac{1}{2\...
Makogan's user avatar
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3 votes
1 answer
203 views

Projection (or fractional-step) methods Vs coupled method for incompressible Navier-Stokes

My question is in the context of the finite element method. Incompressible Navier-Stokes equations can be solved using the coupled method or projection/fractional step methods. Each method has its ...
Chenna K's user avatar
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2 votes
0 answers
175 views

Poisson equation solution in a semiconductor structure

I am trying to solve the $\textbf{1-D}$ Poisson equation for a semiconductor structure at equilibrium (There is no external bias applied). $\textbf{Background}$ \begin{equation} \frac{d^2V}{dx^2} = -\...
0-0's user avatar
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0 votes
1 answer
113 views

Is FDTD A Method for Simulating Quantum Field Theory for Photons?

I have been reading a bit about Quantum Field Theory and Photons, I read that the equation(s) for spin 1 massless particles (photons) in Quantum Field Theory are just Maxwell's Equations described in ...
cgbsu's user avatar
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0 answers
136 views

2D wave equation is numerically unstable using Finite Difference Method

I'm working with simulating both the heat and wave equation in 2D in a Python code. When simulating the heat equation, I learned about the CFL which I used to get a numerical stable solution. I found ...
Tanamas's user avatar
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1 vote
0 answers
35 views

Normalisation in tensor networks

I am trying to implement the iTEBD algorithm for the $PXP$ model, i.e, the hamiltonian is $$H = \sum_iP_{i-1}X_iP_{i+1}.$$ Here $P$ is the projector onto the ground state and $X$ is the usual pauli x ...
Souroy's user avatar
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Geant4, simulate photon emitted into lead

I have just learned Geant4 and recently I tried to simulate photons emitted into lead. After I collected the data and figured out the transmission of photons. I found my data is bigger than the ...
SHZ's user avatar
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2 votes
1 answer
93 views

How to correct for collision in $N$-dimensional bounded motion of a particle?

I want to numerically simulate the motion of a point particle (unit mass) in $N$-dimensional space according to the force $f(\vec{x}, t)$ and bounded by a set of linear constraints (equalities as well ...
haoyu's user avatar
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-1 votes
3 answers
195 views

What evidence exists to suggest that computational science produces more information than studying real phenomena as they are?

What evidence exists to suggest that computational science produces more information than studying real phenomena as they are? I think about this topic often, because I think synthetic knowledge is a ...
mavavilj's user avatar
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4 votes
0 answers
88 views

How to do a parametric study of arbitrary 2D surface?

I need to do a parametric study of the performance of a room heater on different rooms by simulating the temperature distribution in there. The problem here is that the rooms are not simple rectangles ...
Ken Grimes's user avatar
2 votes
1 answer
302 views

Using velocity verlet algorithm for nbody simulation results in planet leaving orbit

I'm new to computational physics and attempting an n-Body simulator in java but for some reason the planet in orbit leaves the orbit when it reaches the fastest accelaration aka the closest point to ...
ght007's user avatar
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1 vote
2 answers
263 views

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 ...
oliverjones's user avatar
4 votes
3 answers
533 views

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 ...
nalzok's user avatar
  • 181
2 votes
1 answer
329 views

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. ...
wosker4yan's user avatar
0 votes
0 answers
179 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 ...
Tepa's user avatar
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1 vote
0 answers
40 views

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 ...
Mandrake_The_Magician's user avatar
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0 answers
238 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 ...
user42169's user avatar
3 votes
1 answer
1k 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 ...
kruemelkeksfan's user avatar
0 votes
1 answer
77 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 ...
mavavilj's user avatar
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0 votes
0 answers
24 views

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 ...
mavavilj's user avatar
  • 427
4 votes
0 answers
105 views

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. ...
mavavilj's user avatar
  • 427
3 votes
2 answers
119 views

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 ...
FourierFlux's user avatar

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