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6
votes
1answer
179 views

How can I simulate a model electronic hole?

Suppose I can solve time-dependent Schrödinger equation for several 1D particles (currently 3). I'd like to see, what an electronic hole is and how it behaves — in a series of numerical experiments. ...
5
votes
1answer
209 views

Smoothed particle hydrodynamics in cosmological N-body simulations

What is the role of smoothed particle hydrodynamics (SPH) in cosmological N-body simulations like the Millenium Run (performed with Gadget-2)?
9
votes
2answers
220 views

In a Monte Carlo NVT simulation How do I determine equilibration

I'm running an NVT (constant number of particles, volume and temperature) Monte Carlo simulation (Metropolis algorithm) of particles in two dimensions interacting via Lennard-Jonse potential ($U = ...
2
votes
1answer
261 views

Boltzmann Distribution of Electrons in Confining Potential

I have a particle simulation wherein many non-interacting electrons are trapped in a electric potential well. I would expect, and therefore I initialize according to this, that the electrons would ...
5
votes
2answers
136 views

Why do liquids exist? [on hold]

This post asks why matter exists in three phases. Most of its answers explain the existence of liquids with some variant of the following: liquids happen when thermodynamic conditions, temperature ...
1
vote
2answers
42 views

Calculate gravity between two points

I am trying to build a simulation of gravity in LibGDX using Bullet physics. To simplify it, I just want to apply a force on some body towered a (0,0,0) point. I got my body mass and it's location ...
2
votes
0answers
27 views

What is the meaning of the Fourier Transform of the electric field of a well guided mode in a dielectric waveguide?

I have been studying waveguiding in dielectrics for a while now; however, I cannot understand the meaning of the Fourier transformed electric field. I will first give some background information. ...
0
votes
0answers
37 views

What would be the long-term effects of stopping the Sun?

TL;DR: In an orbital simulation, what are the effects of pinning the major body to the origin, and how could these effects, if any, be mitigated? Consider an orbital motion simulator; your basic ...
-5
votes
0answers
32 views

If we are living in a simulated world, doesn´t there has to be a first real world? [closed]

There are people who think we are living in a world that´s a simulation in a computer. But if that is the case, doesn´t there have to be a world where a first simulation started? Wich is to say, a ...
1
vote
2answers
53 views

Model/formula for bouncing ball

I'm programming an animation of a bouncing ball, and I want it to be as realistic as possible. I fully understand the physics while the ball is rising and falling: It accelerates downward at 9.8 ...
5
votes
1answer
39 views

Identify binary stars in nbody simulation

I'm doing a nbody simulation, and I'm interested in the formation of binary systems in the temporal evolution. I can identify them by eye, but I don't know an algoritmic criteria that can say me if ...
0
votes
1answer
16 views

Calculating true anomaly of a hyperbolic trajectory from time

I'm creating a simulation for orbiting bodies with my primary challenge being calculating the true anomaly of a trajectory with respect to time. I have figured out circular, elliptical, and parabolic ...
4
votes
1answer
332 views

Boundary conditions on current carrying wire

I'm trying to simulate by finite elements method Maxwell equations for a current carrying wire. My 3d geometry consists of a cylinder and a box containing it. I will use a mixed formulation and ...
0
votes
0answers
23 views

Two axis non linear Inverted Pendulum

I am Electronic Engineering student. Sorry for my english, I am very rusted. I am modeling the inverted pendulum for a Class Project and I wondering if any could answer one question. In this web ...
-3
votes
1answer
71 views

Need motion equations for falling ball for simulating [closed]

I am currently M.S student in artificial intelligence(A.I) and working on my thesis on reinforcement learning, which robot should learn by itself how to control a quadcopter. Long story short, I have ...
0
votes
1answer
41 views

Notation of a vector containing equation in a paper

I'm trying to implement Coulomb long range interactions into a molecular simulation program using a particle-particle/particle-mesh Ewald solver. The following equation from the paper "How to mesh up ...
0
votes
0answers
26 views

Keplerian orbits and radial velocities: problem with true anomalies

I am writing a pure Python code to calculate radial velocities of stars with massive objects orbiting them. I am following the formalism from Murray & Correia (2011) (hereafter MC11). In a given ...
4
votes
1answer
22 views

How would I find the velocity of an object after it doesn't fully enter the gravitational pull of a planet and is kind sling shot out of its gravity?

Obviously that question doesn't have a lot of jargon having to do with math and physics. I am not a physicist, I'm not a mathematician, I'm trying to make a game and simulate some physics found in ...
0
votes
1answer
284 views

Kinematics of a differential drive robot

(I am reposting here a question I asked on stack overflow, since it actually sits right in between programming (modeling of 2D physics) and physics proper (kinematics). I think I have the physics part ...
0
votes
0answers
18 views

2-D Ising model temperature of equilibrium [duplicate]

I have simulated 2-D Ising model in C#, but my scatter plot for magnetization versus temperature is an decreasing line (you know that the correct plot decreases quickly in a temperature near 2.3). ...
0
votes
1answer
118 views

How to simulate pendulum movement with high amplitude

I need to make a C# simulator for a simple pendulum. I have been searching the web for 3 days and I am stuck. The problem is I have found many equations that would give the angle position as a ...
0
votes
0answers
24 views

Why is more difficult for a DFT to converge with non-periodic conditions?

I am simulating a cubic amorphous silica system. When all boundaries are periodic the SCF iteration converges rapidly. However, when the boundary is not periodic in the $x$ direction, the SCF ...
1
vote
0answers
49 views

How do I model the motion of a particle changing acceleration vector (2D)?

I want to model a particle with an arbitrary initial velocity, and estimate the time it takes to reach a final point given a constant magnitude of acceleration. It should take the quickest path to the ...
2
votes
1answer
259 views

Heuristic equation for Friction force between materials

I'm programming a game where different types of objects will be sliding over different types of terrains (Top-down in two dimensions). At my current level of physics education we are given the ...
2
votes
0answers
19 views

Derivation of generation of time between two subsequent particle enters into computational domain

I have problem with understanding derivation of one equation in following problem. You have 1D computational domain (it is not 1D but because it is symmetrical and we are watching only radial ...
1
vote
1answer
294 views

Determing Velocity of Moons

I have a question that I believe is relatively easy to answer, I am working on an $N$-body simulation of a fictional star system and am having trouble finding the velocity of moons so that they will ...
1
vote
1answer
283 views

Simple QFT simulation - how to do it

I would like to write a simple QFT simulation for a free scalar field with a cubic interaction term. However, I got stuck a bit. I will try to describe what I think I understand. I want to have a ...
0
votes
0answers
10 views

Parameters for modelling 4 level 2 electron gain medium for laser

I have an EM simulator that can model laser gain medium by a 4 level 2 electron system. However the model requires pumping wavelength, lasing wavelength, pumping linewidth, lasing linewidth, decay ...
3
votes
1answer
193 views

What equation predicts at what point a stretched object comes apart?

I am creating a simulation and am interested in pulling stretchy things and when they break, like taffy. I imagine this is a bit tougher then a simple equation like gravity, but I have no idea. Is ...
4
votes
1answer
787 views

Moment of inertia of rotating particles in center of mass frame?

I am trying to simulate a collision between two molecules. I know the energy for every position/orientation, from which I can calculate the forces. The treatment is classical and the molecules are ...
1
vote
1answer
135 views

How does the Lennard Jones Potential changes for interaction between particles of different sizes?

I am interested in incorporating a Lennard-Jones potential in a simulation. When the interaction only involves the same type of particle, with same characteristics, we can use reduced units, scaling ...
4
votes
1answer
67 views

How to conserve momentum when numerically-integrating the path of a charged particle through a magnetic field

I have the python script attached below, which is intended to track the trajectory of a charged particle in a static, uniform magnetic field. It is very simple to calculate the instantaneous force ...
0
votes
0answers
24 views

use FEMM to simulate electric field for a magnet inside a coil

I'm trying to simulate a magnet inside of a coil of wire, with and without current running through the wire. I'm using the free FEMM software to try to simulate this, but I don't think i'm setting ...
4
votes
1answer
72 views

Can I re-wind gravity?

Suppose I perform an arbitrary simulation where I integrate the motions of a collection of particles which interact only gravitationally. Suppose I use a time reversible integrator (to be specific, ...
0
votes
0answers
12 views

Why does SCF convergence on DFT worsens for a parallelepiped domain?

I am currently simulating parallelepiped domains of amorphous polyethylene with DFT. I would like to know the reason why the convergence of SCF worsens when the domain is not cubic. Does the k-point ...
0
votes
1answer
35 views

How to simulate an accelerometer in code

I want to write a simulation of an accelerometer (with a fixed X and Y axis in this case but with respect to a world coordinate frame) on a stick, rotating in a circle around a fixed point. From that ...
3
votes
2answers
60 views

Does inelastic collision say the ball bounces back to you when thrown at an angle on ground?

I created a bounce simulation using exactly the formula from Wikipedia. The behavior I observe is not what I would expect in two cases: When two balls hit off-centre, they act the same as if the ...
5
votes
1answer
66 views

Methods for handling close approaches in $N$-body simulations

In direct gravitational $N$-body simulations, what are the preferred methods for handling close approaches between bodies in order to preserve the accuracy of the evolution of the system?
0
votes
0answers
35 views

How to calculate the forces that create precessing motion of a spinning top?

I'm trying to create a a spinning top simulation, and I have a problem with simulating the precession. I read the Wiki article about precession, which have the formula for angular velocity of ...
1
vote
0answers
50 views

Simulating TE011 mode in cylindrical cavity, Comsol [closed]

I have been trying to simulate TE011 mode in a cylindrical cavity by modifying the example given in Comsol ...
1
vote
1answer
56 views

Model of a heating system in an industrial hall

I want to model a heating system in an industrial hall. The system consists of: a heating plant, a pump, 2 pipes (each pipe is 500meters long) and a machine tool. The required heat for the ...
0
votes
1answer
47 views

Cavity resonator modelling and simulation of em fields inside the cavity

I want to model a cylindrical cavity resonator and study the different modes of em fields inside it using MATLAB/COMSOL. Please refer me books/articles or other resources so that I can achieve my ...
0
votes
0answers
20 views

How to find positions in the equilibrium state of mass-spring system?

I've simulated 3D mass-spring system (mesh/network). First the system was in equilibrium state of it own (called state {A}). If I moved some of the masses in the system to the new positions, the ...
1
vote
1answer
44 views

Force of Gravity of a stationary object acting on another object moving through space

Story: I have x and y positions of a spaceship as it moves through space to some goal location at [1000, 700]. A record of its movement is given by: ...
0
votes
1answer
72 views

Newtonian Gravity Simulator?

Could anyone suggest me a good (and possibly free) Newtonian Gravity Simulator software available on the web, where it might be possible to simulate the Solar System dynamics and playing with it, by ...
3
votes
2answers
202 views

Why is my Lyapunov exponent similar for single and double pendulum?

This is my first question here on stackexchange. I hope that I can be understood. If not, tell me and I will reformulate and fill in with details. I have simulated a single pendulum and a double ...
6
votes
6answers
27k views

Free Optics Simulation Programs

I'm having an extremely difficult time finding an optics program that is easy to use and offers accurate physics simulations. I'm not asking for much, I just want to be able to simulate a laser going ...
2
votes
1answer
60 views

What does the solid phase in a two-dimensional system with Lennard-Jones potential look like?

Consider a system of two dimensional particles interacting via Lennard-Jones pair potential: $$u(r) = 4[(\frac{1}{r^{12}})-(\frac{1}{r^{6}})]$$ where r is the distance between two particles. What does ...
3
votes
2answers
56 views

Can I identify phase (solid, liquid, gas) just from a snapshot of molecule positions?

Suppose I have a simulation of a bunch of nitrogen molecules (N_2). Just by looking at the positions of a bunch of the molecules in a volume of space, how can I tell whether the picture is showing a ...
1
vote
1answer
132 views

Scalable tool (engine) for simulating the universe

Does there exist a large scale scalable tool (engine) for simulating the universe that incorporates both quantum mechanics and cosmology, i.e. micro & macro scales? (It would be best if this tool ...