Simulation is the process of mimicking the behaviour of a real physical process or system using a representative model.

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152 views

Efficient Gravitational Field Implementation

I asked a similar question on physics.stackexchange, being ignorant about this website. I am basically looking for an efficient way to implement gravitational fields. I have a huge 2D space, with ...
3
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0answers
35 views

Discretizing boundary conditions for vortex methods

I am working on a fluid simulation using vortex methods. For this I must compute the vortex sheet on my boundaries given as: $$ \gamma(\mathbf{x}) - \frac{1}{\pi}\int_S ...
3
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1answer
79 views

Euler's equations for a tube with varying cross-section

$\def\pd{\partial}$ $\def\l{\left}\def\r{\right}$ $\def\mdot{{\dot{m}}}$ $\def\eps{\varepsilon}$ Consider a tube with longitudinal coordinate $x$ from $0$ to $l$ and varying cross-section $A(x)$. ...
3
votes
3answers
76 views

Monte Carlo estimation of Pi with Buffon's needle

Is there a way of estimating Pi with the Buffon's method without assuming Pi known? To be more precise: in a Monte Carlo simulation of the experiment invented by Buffon I would (ideally) generate 2 ...
1
vote
1answer
102 views

Celestial mechanics simulation software? The 'N-Body Problem'

What software or sites might simulate an N-body gravitational problem? Application is related to Klemperer Rosette or Iridium Satellites. Bias for C, C++, PHP, or Java. Nice visuals a big plus. ...
4
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0answers
60 views

Tracking for two meshes

I'm dealing with physical simulation (position based dynamic). Now I'm trying to realize tracking for two meshes. In order to explain what does it mean, let's assume that we have two similar meshes: ...
0
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0answers
40 views

Numerical strategy to detect the point of detachment over the wall of cylinder in the simulation of unsteady flow over circular cylinder

I am working on unsteady simulation of flow over circular cylinder where we get Kármán vortex street. Kármán vortex street is a repeating pattern of swirling vortices caused by the unsteady separation ...
3
votes
1answer
82 views

Increasing thread number degrades performance

I have a problem with parallelization and the brownian dynamics (molecular dynamics) code that I am using. We have our own home-grown framework at the university, and recently we've made the change ...
4
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2answers
78 views

Solving system of differential equations with interconnected boundary conditions

I am trying to solve the following system of differential equations numerically over the domain $x=0$ to $x=D$. The main difficulty is that the boundary conditions are interconnected and depend on the ...
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0answers
23 views

Generating magnetic turbulence spectrum

I am trying to code up a model of magnetostatic turbulence and am having issues with the build. The paper that I am referring to is titled "Anomalous diffusion and Lévy random walk of magnetic field ...
0
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0answers
43 views

Sorting eigenvalues by the dominant contribution

[Edited to simplify the question] I am trying to associate the eigenvalues $E$ of a matrix $H$ to the original rows of the matrix. Moreover, it would be trivial to sort the eigenvalues in ascending ...
6
votes
2answers
102 views

Simulating advection over a network of 1D pipes

I am trying to create a simulation to help visualize how different chemical components flow through a network of pipes with associated valves, pumps, and chemical inputs. In this simulation, the pipes ...
0
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0answers
37 views

Calculating the number of molecules diffusing out of a volume

I have a system of reactions that are governed by differential equations. They are reacting inside of a volume with known dimensions i.e l*b*h. I don't have any other information on their position ...
1
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1answer
221 views

Particle Tracking Code - MATLAB vs. C++

First some background, I am a mathematician by training with very little formal training in programming. I am most comfortable in MATLAB and have been working with it for a long time. My second choice ...
0
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0answers
99 views

Problem with initial/boundary conditions for 1D flow simulation

I am trying to simulate numerically the flow between the atmospher and a pipe in Matlab, where the initial condition within the pipe is ...
2
votes
1answer
78 views

Detect rigid body motions in a cloud of points

This question popped up today in our group meeting. Suppose you are given a cloud of N points in 2D and each is associated with a velocity vector. These points are associated with particles on a 2D ...
3
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0answers
73 views

N-body simulation for particles

I would like use N-body simulation for measure a torque on an object in a liquid (helium). It's a 2D study. On the site : http://www.browndeertechnology.com/docs/BDT_OpenCL_Tutorial_NBody-rev3.html I ...
3
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0answers
97 views

Sound Waves Simulation in 3D Environment

I want to do a simulation of sound waves including wave propagation, absorption, and reflection in 3D space. I did some research and I found this question in stackoverflow but it talks about ...
0
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0answers
196 views

Magnetostatic and magnetodynamic problems in freefem++

I would have liked to use freefem++ for implementing some simulations as in the title but I didn't find anything about it. I know it does implement Nedelec elements but I don't know for example how to ...
1
vote
4answers
228 views

Best PARALLEL numerical solver of first order differential equation

I have a system of 256 differential equations that I want to solve numerically. The system represents the Liouville equation, which is a first order, linear differential equation with complex numbers. ...
6
votes
2answers
178 views

Feasibility and software for acoustic simulation

I'm looking at doing a finite-element simulation of air flow essentially for the purposes of approximating the response to an external audio impulse of a smallish (~10-30 cm scale), stationary ...
0
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0answers
36 views

How can i find the coordination number with voro++?

Could anybody please help with voro++ cause i am new to this software?My problem is how can i find the coordination number of an atom ,cause i checked it for a bcc lattice and it gave me 24 for all ...
0
votes
1answer
81 views

Non-deterministic/probabilistic molecular dynamics simulations

I'm looking for a piece of software for performing molecular dynamics simulations with the following specifications: required: well published (as in there are papers citing it in one or more ...
3
votes
1answer
78 views

numerical inaccuracy ellipsoid-ellipsoid collision

I am trying to implement ellipsoid-ellipsoid collision in my C++ code. Briefly this task can described as next: Let's assume that we have two arbitrarily oriented ellipses in the in space and this ...
2
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0answers
71 views

What are the governing equations solved in coupled atmosphere-ocean models?

In (hydrostatic) atmospheric general circulation models, for example the so-calle Primitive Equations, consisting of the horizontal momentum equation, the hydrostatic balance, the continuity equation, ...
4
votes
3answers
140 views

Is Discrete Exterior Calculus currently a focusing point in numerial computing world or simulation in industry,

I am just wondering if Discrete Exterior Calculus, as a new numerical method , is good at numericall solving problems in elasticity, fluids or other physical/real area.
0
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1answer
92 views

Simulating the motion of a elastic body under gravity [closed]

I am doing a numerical simulation of a elasticity problem. It is very simple. A cuboid elastic body with the right end fixed on the wall, under the gravity(but here I set it to be 1 along the z-axis ...
0
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0answers
168 views

Any note on Immersed boundary finite difference method?

For parts of a talk, I need a note on "Immersed boundary finite difference method", mainly about the reason of appearing this branch in the finite difference methods, considering mathematical ...
3
votes
4answers
131 views

Finding a molecular dynamics visualization library for C

I asked this question over at stackoverflow, and got blasted for it. I am currently working with legacy MD code written in C that my university uses, and haven't moved to a more modern library like ...
1
vote
1answer
97 views

Simulate aerodynamics of a general shape object

I'm trying to code a simple physics simulator in C++ but I'm stuck on the air resistance issue. Surfing the Internet I only find a drag coefficient for very basical area shapes when the air is ...
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0answers
32 views

Spectra of the energy flux VS transfer spectra?

In direct numerical simulation of turbulence what is the advantage to look at the spectra of the energy flux rather than the transfer spectra? The transfer spectra corresponds to the triple-velocity ...
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0answers
63 views

References on the topic of DEM and XDEM

DEM: discrete element method. XDEM: extended discrete element method. For my current project of furnace simulation with granular materials, I am interested in the methods mentioned above. I have not ...
0
votes
1answer
92 views

What is the time_step and how many iterations required for convergence purpose in fluids simulation [closed]

My question seems elementary: I use a new numerical method to do fluids dynamics simulation. I use t=0.001s as the time step. But I don´t know how many iterations I need to achieve velocity ...
3
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0answers
95 views

How to estimate if a velocity field is statistically homogeneous?

For a 3D velocity field $\mathbf{u}$ obtained by direct numerical simulation. Assuming that the field is defined on a periodic domain $\mathcal{P}$ of periodicity $L_x$ in the $x$ direction, $L_y$ ...
6
votes
3answers
208 views

Finite-size effects in molecular dynamics simulation

I will be blunt: this is an old exam question of a course that covers Molecular Dynamics (MD) and Monte Carlo (MC) simulations. Explain how to determine the severity of finite-size effects. My ...
3
votes
1answer
90 views

Use of random numbers in the Metropolis algorithm

In the Metropolis algorithm, we accept or reject based on following criterion in the $NVT$ ensemble: $$ e^ {(E_{\text{new}} - E_{\text{old}})\,/ \,kT } \ge \text{random}(0,1). $$ Why does the ...
0
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0answers
39 views

Powerspectre and autocorrelation

The following is related to this question. I have some "wind" I have computed with a script in matlab. I.e. a vector, where each component corresponds to the wind speed in some point, measured in ...
1
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0answers
43 views

Energy anomolies in many body simulation

I am trying to simulate the gravitational interaction between many bodies. I am using a direct PP force calculation and a 4th order symplectic integrator with a variable step size. The energy of ...
1
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1answer
48 views

Counting valency of atoms, in a molecule with python

The documentation for the indigo module can be found here http://ggasoftware.com/opensource/indigo/api#inputoutput So for instance if I have a molecule object for some SMILES string, e.g. ...
0
votes
1answer
121 views

Modelling the properties of a cord/wire/string [closed]

I am trying to simulate the physical properties of a real-world cord/wire, with finite diameter, length and mass. I would like to come up with a computational model of the properties of elasticity, ...
5
votes
1answer
132 views

Stabilization of solution to one-dimensional system of PDE

I am trying to solve numerically next PDE system: $$\frac{\partial c}{\partial t}=\epsilon\frac{\partial}{\partial x}(\frac{\partial c}{\partial x}+\rho\frac{\partial \varphi}{\partial ...
3
votes
1answer
633 views

How to do co-simulation with two FMU models

I have two FMU developed with different simulation tools. I would like to connect them through some variables and run a co-simulation with an open source tool as OpenModelica. This co-simulation has ...
3
votes
4answers
240 views

Finding the correct Molecular Dynamics library

I just started working on some Biophysics research, and I was looking around for a good MD library to use. There is one right now at the university set up in C, with openMC parallelization, but the ...
1
vote
1answer
68 views

Simulating evolution of comet

I have to present a working 3D simulation of an arbitrary comet in a close proximity to the Sun or to the Jupiter. In specific, I want to simulate comets D/1993 F2 and C/2011 W3, using the theoretical ...
3
votes
1answer
88 views

Is using Monte Carlo method a good approach for solving Boltzmann equation?

I'm trying to solve for electron and hole distribution function using Boltzmann equation with various scattering mechanisms. Since I land up with an integro-differential equation, analytical solution ...
2
votes
1answer
131 views

Simulating laminar fluid flow in microfluidics device

I just started working in a lab that is trying to design microfluidics devices to trap and manipulate colonies of E. coli cells. Given a 3D model of such a device created in Autodesk Inventor (or a ...
3
votes
1answer
132 views

Verlet Leap-frog Method of approximating orbits

I found the following simulation of an orbit given the semi-major axis of the ellipse, eccentricity, initial velocity, the mass of the object being orbited, and initial position of the orbiting ...
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votes
1answer
50 views

How to evaluate 1st and 2nd order reactions, with rate constants and fluxes?

I want to implement differential equations in C# from Open Cell cellml file. The mathematical model is described in this article. I have parsed xml, and calculate operations, but can't correctly ...
8
votes
4answers
477 views

Is CFD used in animations / movies / art?

This is not a technical question, and is asked just out of curiosity. Are CFD simulations used in animation movies? (something like shallow water equations, explosion problem etc.) In other words, ...
0
votes
1answer
96 views

Spring damper model does not work very well

I'm trying to model a spring damper system from a tutorial that I've found on this site. If I use the exact same parameters as the ones in the tutorial the system is not stable. I've downloaded the ...