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Questions tagged [simulations]

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What are some good physics engines for computations? [on hold]

I am interested in knowing what kind of physics engines for academics exists in the industry. Whether one is working on cosmology to electromagnetism to quantum mechanics, are there any general ...
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0answers
9 views

Lens simulator with geometrical optics [duplicate]

I'm looking for a lens simulator to see rays from geometrical optics, possibly easy to use. For now I'm playing with OpticalRayTracer that works perfectly for a preliminary simulation. I would like a ...
2
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2answers
62 views

Simulation software to solve high school level mechanics problems

I'm a physics teacher and I would like to find a simulation software that could be used to give exact numerical answers to high school level problems in Newtonian mechanics. I want the students to ...
2
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0answers
29 views

Amount of particle collisions depending on entropy

I'm doing a very simple simulation of random particles. Simple mechanics, elastic collisions. (The simulation is based on a next-event time progression.) When I count the number of particle particle ...
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0answers
25 views

Metropolis method under the Gand Canonical Ensemble

I am writing code to simulate Langmuir adsorption using Metropolis method under the Gand Canoninal Ensemble. Aided by the Wikipedia Article, I derived the corresponding equation, proposed a sample ...
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0answers
29 views

Davis formula application

So I stumbled upon the Davis formula for trains while doing some researches about my project but I don't know how to apply it (programmatically) : Let's say for example this variant : $$R'=1.3+\frac{...
3
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1answer
94 views

Train Physics Simulation

It's my first time asking here so bear with me. I'm a computer scientist, and I'm working on a train simulator project. I'm having quite a difficult time understanding all the physics and formulas ...
2
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1answer
19 views

Magnetic susceptibility error by binning Monte Carlo

I am studying the 2D Ising model using Monte Carlo simulations and I have learned the binning (or batching) method for the error statistical analysis. Following this discussion https://books.google.it/...
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1answer
25 views

What would be a correct/natural approximation for the curve of bended materials?

Would it be a cubic/quadratic Bezier curve? Or perhaps (part of an) ellipse? I am a computer science student who is working on a physics engine using realistic materials, meaning I would like for ...
2
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1answer
60 views

Simple heater (radiation) model for PID constants tuning

I've searched around a lot and maybe I just don't know what exactly to search (and even ask here) for, but I'd like to create a simple model/function of a heater dissipating heat to surrounding air, ...
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0answers
32 views

How to measure a Bell inequality violation in IBM Q? (Or analytically)

I made some circuit to prepare a 2 qubit state, but I am having trouble understanding how to measure Bell's inequality. I know the inequality is of the form $$|E(a,b)-E(a,b')+E(a',b)+E(a',b')| \leq 2$...
1
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1answer
32 views

Monte Carlo error propagation

I want to assign an error to the standard deviation computed with a Monte Carlo error propagation method. Now, I explain better. If we have a random variable $x$, with mean value $x_0$ and standard ...
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0answers
7 views

Simulation in Simion

I am facing some problems in Simulating linear rf trap in Simion. I made four cylindrical rods. and made TOF spectrometer with the einzel lens, defined some particles originating from the center of ...
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0answers
20 views

Simulating torque between axially magnetized cylinders

Consider the following system of cylinders with axial magnetization (shown in red): Let cylinder 1 be the top cylinder and cylinder 2 the bottom one. The origin of the system is placed at the point ...
1
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1answer
62 views

Analytic Solutions to Magnetic Fields of Circular Current Loop

I came across an interesting problem and am wondering if there is a quick answer to it from someone who's done this before before I whip out the books of integral tables. Analytic expressions from ...
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0answers
32 views

How to determine two elastic tensors are similar?

A elastic tensor is a 3*3 symmetric matrix that determines some material property. I have a elastic tensor A and I want to find the most similar elastic tensor B from a collection of elastic tensors {...
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2answers
25 views

Which force do I use for work done by an engine

I'm busy writing a train simulator. I need to calculate the fuel consumption of the locomotive. I know that Work = Force x distance. From that, I can easily use energy density and work out how many kg ...
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0answers
22 views

Visual simulation of gravitational lensing

Is there a way to generate an accurate visual computer simulation of gravitational lensing?
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0answers
136 views

$N$-body gravity simulator: why does energy conservation break down when introducing an adaptive timestep?

I am playing with an N-body gravity simulator using the velocity-verlet algorithm. In the actual simulation I normalize everything so that it is nicely behaved numerically, but I'll express things in ...
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0answers
38 views

Error in histogram measurements

I ran into the following statement here and here but I believe it's more general. Let's suppose we're running a simulation of a system and we are interested in the distribution of a quantity (say $M$...
1
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1answer
44 views

Cross sections in Geant4 [closed]

Does anyone know where I can find the information about cross sections in Geant4? I would like to use my own file with cross section (exported from another code to MC simulations), but I cannot find ...
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0answers
19 views

Numerical simulation of electromagnetism force from random wire

I want to learn numerical simulation and as my first project I would like to simulate electromagnetic field derived from DC flowing in random shaped wire. Are Maxwell equations enough to calculate 3D ...
0
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1answer
30 views

Potential Flow integration (no-voice and very beginner!)

Let's say I managed to compute a velocity field that is divergence-free. How do I integrate it over time? meaning, I created a potential function, set v to be curl of potential function, so I have now ...
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0answers
16 views

Gauge fixing in Ginzburg-Landau simulation

I am developing a computer simulation of the Ginzburg-Landau model of superconductivity. In a few words, I have discretized the domain with finite differences and I am using Nonlinear Conjugate ...
4
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1answer
104 views

Assumptions for 2d simplification of Navier-Stokes flow

There are many cases where Navier-Stokes flow is simplified to a two-dimensional problem to reduce the costs for a numerical simulation, e.g., flow around an airfoil, channel flow or pipe flow. To ...
2
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2answers
94 views

Wave simulation without reflection on the boundaries [duplicate]

I would like to numerically simulate a wave (let's say in a string) with different boundary conditions: Fixed endpoints Periodic Boundless $\varphi(x, t)$ is the value of the wave (vertical ...
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0answers
16 views

Heat transfer in Steady vs Oscillating flow through a Matrix material (Conceptual Input needed)

I have been trying to model heat transfer and pressure drop for oscillatory flows inside a closed channel flowing past a matrix material. My intuition and experimental results (in journal papers) tend ...
1
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1answer
38 views

The actual mass of a particle in coarse-grained molecular dynamics

If I use Lennard-Jones unit with the fix langevin command, and set both the mass and damping parameter as 1, does it mean the actual mass of a particle in this ...
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1answer
44 views

How to deal with constants on computer simulations? [closed]

I'm beggining learning about natural simulations on my courses and I had a few questions about time, and especially with the game "Universe Sandox²". I know about the basic Newton's formulas about ...
2
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0answers
32 views

Geant 4, simulate Tc-99m decay

I have a setup of Monte Carlo simulations in Geant4, and I'm able to simulate radioactive events from isotopes such as I-131 and F-18, which are defined in the RadioactiveDecayData5.2 files. Tc-99m ...
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0answers
40 views

Time units in simulation

I am hoping that someone could give me some insight about my problem. Currently I want to simulate the evolution of a gaussian wavepacket in a time-dependent potential using the Crank-Nicolson scheme. ...
2
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1answer
70 views

Doubt while simulating electric circuits

Today, I was simulating DC electric circuits just for knowledge and fun using PhET interactive simulations. But I'm having trouble understanding these circuits which I made. I think that both these ...
2
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2answers
37 views

How can I determine a planet's mass based only off of information about its orbit and its parent star?

I'm coding a video game with procedurally generated planetary systems and I want some and I want to make sure I'm at least somewhat scientifically correct. I've reached the part in my code where I ...
0
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0answers
12 views

Determine Field of View from Given Simulation Box Size

I want to determine the field of view as would be seen by a telescope corresponding to a simulation box size(comoving) of, say 100^3 Mpc^3.As I understand the box size for simulation is a rough ...
2
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0answers
20 views

How to set the number of fermions in the whole system in fermionic-DMRG program?

In infinite DMRG (density matrix re-normalization group) algorithm, we increase size of super-block by two sites in each iteration. How do we set number of fermions in the system? Let's say we want to ...
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2answers
58 views

In Wang Landau method, how can I avoid large entropy difference?

Summary: In Wang Landau method, you have to calculate the probability $\exp (- \Delta S)$ but $\Delta S$ is generally large when the size of the system is not small. How can I make $\Delta S$ small? ...
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0answers
88 views

How to deal with fermionic operators in density matrix renormalization group (DMRG)?

Let we have 1D Hubbard model with spinless fermions $$H = -t\sum_i^{L-1} \big(c_i^\dagger c_{i+1}+c_{i+1}^\dagger c_i\big) +V\sum_i^{L-1} n_i n_{i+1}$$ Though this model can be mapped onto XXZ ...
2
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0answers
34 views

Stability criterion for leapfrog in relativistic physics

I am doing a 2D MD simulations of charge carriers in graphene using the Leapfrog algorithm. I am trying to prove that, in some specific cases (when distance between particles is small), the method is ...
2
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1answer
40 views

What is this secondary transition in the simulation of the Ising model?

Here, the horizontal axis is the strength of the ambient magnetic field. The Hamiltonian I used is $$H = -h\sum_i \sigma_i - J\sum_{\langle i \, j \rangle}\sigma_i\sigma_j.$$ The horizontal axis is $h$...
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0answers
76 views

Wolff cluster update in Monte Carlo simulation - at critical temperature [closed]

A general question to the Monte Carlo experts. When I use Wolff algorithm for global updates, say for Ising 2d, I always flip at least one spin (the initial random spin in the cluster). So, near the ...
0
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0answers
26 views

Is there a mass spectrometer software that can measure the mass of a hydrogen atom [duplicate]

For a school project I need to measure the mass of a hydrogen atom either as a lab experiment or with a computer simulation. Since I don't have the appropriate equipment for the experiment, does ...
0
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0answers
47 views

Is there a mass spectrometer software that can measure the mass of a proton

I spent a lot of hours looking for mass spectrometer software (or Cathode-ray simulator) that can measure the mass of a proton or any sub atomic particle. Until now I only found software that work on ...
10
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2answers
392 views

How can one obtain the metric tensor numerically?

I am self-studying General Relativity. Is there a method for obtaining the metric tensor exterior to a specified mass distribution numerically? In the simplest case of a spherical mass this should ...
0
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0answers
36 views

Resonant frequency of Split Ring Resonator (SRR)

I am working on circular and square split ring resonator design as part of my thesis. I wrote a Matlab code to calculate SRR resonant frequency but I am not getting the same answer of any published ...
0
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1answer
73 views

Screening of a coulomb-like potential

Imagine that we have a potential in the form of: $U(r) \propto \frac{1}{r^n}$ in a 2D system, with the high concentration of particles interacting with the above potential. How do you find the ...
0
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1answer
53 views

Ising magnetization in metropolis

I am working on the Metropolis-Montercarlo algorithm for the square lattice ising 2D. Im running the simulations for a given lattice size, running from low temperature to high temperature, and ...
0
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0answers
28 views

Entropy in the Klimontovich Picture of Kinetic Theory

In the Klimontovich picture of kinetic theory, a classical $N$-body system is fully specified by the phase-space distribution $$ \rho(\vec X,t) = \sum_{i=1}^N\delta[\vec X-\vec X_i(t)] , $$ where $\...
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0answers
54 views

Negative Eigenvalues of the Hessian

I am calculating the eigenvalues of the Hessian for a ferromagnetic system. My energy has the zeeman term, a nearest neighbor exchange term, and a dipole-dipole term. I create the hessian where my ...
1
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1answer
78 views

Metropolis Monte Carlo Phase Transition for small systems

Metropolis Monte Carlo simulation for the argon liquid fails to reproduce correctly the pressure-temperature isotherm from the point of liquid-vapour coexistence: Why such a phenomenon appears ? The ...
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4answers
153 views

Is it possible to draw a potential landscape for this system?

Attention: The question was modified for numerical solution. (see Update 2) I have the following system of differential equations: \begin{align} \dot x & = -x+F(a\,y+b),\\ \dot y & = -y +F(...