# Questions tagged [simulations]

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44 views

### Trying to find constant of motion formula

I have a ball that oscillates around a point. The ball have an origin and a destination (the point where the screen is touched). This destination is the equilibrium. One operator gave me this equation ...
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### Can we simulate hydrogen atom formation?

Is it possible to simulate the formation of a hydrogen atom from a single free electron and a free proton? The Hamiltonian for the Schrodinger equation of a free electron and free proton is the same ...
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### How can I reproduce this mass-spring effect? [closed]

I am trying to reproduce the multiball object of this app (you can download it to see by yourself). Press 'e' if you want to emulate the object on your computer (this is a tablet program). Here is a ...
32 views

### Golf Putt Equation - Rolling ball accross an inclined plan with friction [closed]

I want to find the equation, which for any given Golf Putt will give the initial speed and angle at which the putt need to start in order to go into the hole. So this case can be simplify as a ball ...
13 views

### Magnetism Simulator For 3D Models

NOTE: I don't know where to ask this type of question so if this is not the right place, please let me know and I will move it to the place you recommend. I have a 3D model designed in Fusion 360, and ...
112 views

### Can I say two physical systems are isomorphic?

I wonder if it makes sense to say two physical systems are isomorphic to each other. Say if I have a system of electron spins in a magnetic field, and another system with an ammonia molecule. Since ...
54 views

### How can mass diffuse out of a lagrangian control volume when it always tracks the same mass?

I am trying to understand how mass conservation in fluid flow works and how it relates to lagrangian and eulerian control volumes. The way I understand eulerian control volumes is that they are ...
27 views

### What is the thermal conductance of a typical gaz-solid interface?

I'm trying to numerically compute the macroscopic heat exchange in a simple system: a solid body surrounded in gas, initially at different temperatures. I, unfortunately, could not find any reference ...
28 views

### Spin glass observables in Monte Carlo simulations

I am currently simulating an Edwards-Anderson spin glass using standard Metropolis Monte Carlo techniques. The spins are placed on a 3D cubic lattice with periodic boundaries and take on Ising values (...
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### Relationship between extinction coefficient and the imaginary refraction index

I'm trying to add an ITO glass material made by SPI to an FDTD Lumerical simulation. For that I need the real and imaginary parts of the refractive index. In their website though, they give the real ...
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### Relationships between G magnitude, Johnson V magnitude, and spectral type of stars?

I'm simulating a population of binary stars for a summer research project. I'm adding uncertainties to my simulated observables such as angular position and radial (line of sight) velocity. I'm using ...
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### Recovering data from LAMMPS MD simulation

I'm simulating a Lenard Jones fluid with LAMMPS. I already have the simulation but I have the problem of recovering data. I'm interested in pressure vs time, pressure vs position, temperature vs time, ...
31 views

### Negative diffusion, or force that changes particle velocity distribution

Here is my problem: I am studying the dynamics of particles with a 1D "random" force. This "random" force is expressed as a Fourier series (sum of cosines) with a random initial ...
35 views

### Canonical partition function, simple model of 2D polymer

I am trying to simulate using monte-carlo method the behavior of a simple of polymer. The model - The polymer is made of N bars with length a , each bar can be placed in +a or -a relative to the end ...
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### In non-equilibrium energy calculations, how do you handle negative formation enthalpies?

I'm working on some simulation software at the moment which deals with high speed flows in chemical non-equilibrium (including plasma states). When the code initially calculates total energy, it uses ...
24 views

### Find an optimal shape analytically

This is better described with an example: Imagine we posses our current understanding of physics, but we do not know how to make an airplane because we do not know about airfoils. To make this more ...
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### How is Smoothed Particle Hydrodynamics different from Peridynamics considering both have a concept of horizon or smoothing length?

I've been working with Smoothed-Particle Hydrodynamics (SPH) to simulate a ballistic impact problem. While looking into other meshless methods, I came across Peridynamics. It seems the fundamental ...
22 views

### $T$-dependence of magnetic susceptibility for the 2D Heisenberg model

As part of a numerical study of the 2D classical ferromagnetic Heisenberg model, I was asked to plot $\ln(\chi)$ vs $T^{-1}$ and determine the $T$-dependence of the magnetic susceptibility in the low-...
57 views

### Problems with Sun-Earth-Moon simulations in vPython

I'm trying to simulate the Sun-Earth-Moon system using the Verlet algorithm with vpython. I'm using natural units and a cartesian coordinate system, and am having trouble working out the physics. I ...
18 views

### Symmetry breaking in the compressed column buckling

When a compressed slender column buckles, how does the symmetry break and the beams chooses a specific plane to buckle; The differential eq. solution only describes the mode (shape ) of the buckle but ...
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### Literature on predicting overall device behaviour using component-wise simulations on superconducting quantum devices

I am looking for literature on combining electromagnetic analysis of individual superconducting quantum devices to predict overall device behaviour, for instance using tools such as HFSS
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### Could an external being predict quantum uncertainty given all the information of our Universe? [duplicate]

I'll elaborate and be more specific. I understand that this is almost a metaphysical question but nonetheless I want to give it a try. Could an external being outside our Universe create 10 ...
17 views

### How to use Bennett Acceptance Ratio (BAR) method to calculate chemical potential?

In Understanding the Bennett Acceptance Ratio (BAR) method the BAR method is explained. I do not understand how to use it to compute chemical potential (I don't know what $U_0$ or $U_1$ is). I think ...
43 views

### Calculating linear acceleration from torque in a car [closed]

For fun, I'm trying to play with really simple simulation of a Tesla Model 3. Modeling its acceleration and such. But I've hit a roadblock early on despite validating my math several times. What I ...
16 views

### Looking for input to a simple transformative Ab initio molecular dynamics (AIMD) trajectory simulation

I'm looking for a simple Ab initio molecular dynamics (AIMD) simulation of some small molecular system that I can run myself on a desktop computer. I want a molecular system that actually changes ...
41 views

### Developing FEM/FDTD for Computational Electromagnetics

I am looking to create my own code/model for modeling electromagnetic problems via Finite Element Method and Finite Difference Time Domain method. I have been reading through the literature and ...
20 views

### How can FDTD be divergence free when approximating co-located points of E and H on the Yee cell?

I am using this source as a means to produce a 3D FDTD code which can handle anisotropic material. Because tensors are used, all components of the $E$ and $H$ fields must be used when calculating the ...
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### Is $\phi^4$ theory unstable?

I tried to write a simulation of a $\phi^4$ theory for 2+1 dimensions. But whatever values I gave for the coupling constant it always seems to blow up. i.e. a wave-like equation with a mass and ...
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### Sampling anharmonic oscillator paths with path integral monte carlo

I was wondering if I'm justified in trying to use an MCMC sampler to generate positions $q$ which are distributed as $P(q) \sim \langle{q}|{e^{-\beta \hat{H}}}|{q}\rangle$ (where $H$ is the ...
27 views

### No sign problem in quantum Monte carlo simulations of 1D systems?

I've heard many times people saying that there is no sign problem in the quantum Monte Carlo simulations of 1D locally interacting quantum systems. I think this means, for any 1D locally-interacting ...
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### How do I add a refractory period in neuronal spikes generated via Poisson process?

Spikes can be generated via MATLAB code as below ...
44 views

### Deformation of a sphere

I am currently building a computational model for a simulation of a rover landing on the surface of mars. As part of the assignment I need to model airbags being used to cushion the fall. (Assuming ...
121 views

### How do I simulate 2 atom interaction? [closed]

I want to build a rough atom interaction simulator, where is push 2 (or more) atom towards each other and they should behave some have physically correct - attract, bond or repel with some force. So ...
15 views

### Compression of airbags

I am currently creating a simulation of a rover landing on mars. Part of the landing would include the rover being dropped to surface of mars whilst surrounded by airbags. I understand that using ...
29 views

### 2D Incompressible Fluid Simulation solving / diffusion factor

I've been reading about fluid simulations - specifically, incompressible fluid dynamics using the incompressible Navier-Stokes equations. Every resource I've looked at has two key components that I ...
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### Simulation of open quantum system

I want to build a simulation of the dynamics of an exciton in the FMO complex (i.e. protein), is there any platform this can be used in this case? or any helpful idea?
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### Algorithm for Grand Canonical Monte Carlo (GCMC) Molecular Simulation - Initialization

I am trying to make sense of the GCMC algorithm in Frenkel and Smit. I do not understand the conditional statement if a particle is to be displaced or exchanged(removed or added) in a Monte Carlo ...
50 views

### Determining final conditions of boiling water in closed system

I am attempting to develop a simulation of the boiler of a steam locomotive for a video game. Assume we begin with a rigid vessel of volume $V$ entirely filled with known masses of liquid water $m_l$ ...
38 views

### Ripple tank simulation for simulating light waves?

Can anyone help shedding some light on how ripple tanks are programmed? example I'm looking to simulate light waves, to perform theoretical calculations, as opposed to for just visual effect. The ones ...
112 views

### Analytical solution of the thermal conductivity equation [closed]

What is the exact analytical solution of a 1D thermal conductivity PDE: $\dfrac{\partial T}{\partial t} = \alpha\cdot \dfrac{\partial^2 T}{\partial x^2}$, where $T$ = temperature, $\alpha$ = thermal ...
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### Trying to code Kepler's law as a function of Time (has work-around) [closed]

NOTE: This problem has an acceptable workaround. It's a (fun?) question for mathematicians, but since performance is not a huge issue here, there's no major necessity for the problem to be solved. I'm ...
152 views

### Decorrelation times for a 2D Ising Model over a range of temperatures

So, I'm trying to simulate the Ising Model on a 2D square lattice of spins. When exploring the auto correlation of the magnetisation: Where the auto covariance: A(T) = \langle(M(t)\ - \langle M\...
174 views

### Energy conservation in systems with discrete time

Numerical simulations of classical particle dynamics usually break energy conservation due to discretization of time. Is there any explicit numerical scheme that does not break energy conservation (...
I'm solving the Schwarzschild geodesics numerically, and I'm wondering if the result I'm getting makes physical sense. The parameter of the path $x^{\mu}=(t,r,\theta,\phi)$ is the proper time $\tau$, ...