# Tagged Questions

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

7 views

### RCWA for Non-Periodic Structure?

I have a quick question regarding Rigorous Coupled Wave Analysis (RCWA) for numerically solving problems (in optics). I am trying to simulate a device which is non-periodic in x, y directions (but is ...
31 views

### Error in MD simulation with Lennard-Jones potential in C, resulting in a lack of conservation of energy

I'm working on a MD simulation using the Lennard-Jones potential and the Velocity Verlet algorithm. The code compiles and runs, but the energy for each time step is not conserved; it decreases ...
30 views

### How to optimize interaction of flexible 3D shapes in space/what is this technique called

I am not sure what terminology I should use here or even what field this is. That information itself would be incredibly helpful, this is new territory for me. I'm trying to figure out how to solve ...
52 views

### How does Multi Body Dynamics software work for flexible joints?

I need to model a "fishing rod" in 2 dimensions by joining several "rigid sticks" by flexible/elastic joints. The joints act as plate/torsion springs with different spring constants. The "fishing rod" ...
24 views

### Rogallo Procedure

can anybody please give an explanation on how Rogallo's procedure is carried out exactly to build up initial conditions for DNS simulations for Homogeneous Isotropic Turbulence ?
18 views

### Simulation of Parabolic Cylinder Function $U(a,x)$ for complex arguments

According to Wolfram Mathworld $U(a,x) = D_{-a-1/2} (x),$ and $D_v(z) = 2^{v/2}e^{-z^2/4}U(-\frac{1}{2}v, \frac{1}{2}, \frac{1}{2}z^2)$, Using the GNU Scientific Library (GSL) it seems possible ...
133 views

### Three body problem in C++

I am in a begginers programming course and we got a little project. I chose to simulate the three body problem using the Euler method. Even though the system is chaotic there are some special cases ...
105 views

### Initial conditions of nbody problem

Note: I have edited the original question to try to be clearer. I'm trying to simulate a gravitational nbody problem with a Barnes-Hut algorithm, in which the bodies start in a homogeneous sphere ...
42 views

### Convergence Criteria for Two Fluid Flow Solver

Which one of the following is suitable for judging convergence in Two-Fluid Flow Solver? 1) Absolute Residual (L^2-Norm). 2) Relative Residual. 3) Fraction Change in Velocity, Pressure and Volume ...
51 views

### Mobile robot path following using model predictive control (MPC)

I'am trying to implement a path following algorithm based on MPC (Model Predictive Control), found in this paper : Path Following Mobile Robot in the Presence of Velocity Constraints Principle: ...
45 views

### Rotation of acceleration data into earth frame using quaternions [closed]

I am working on a project to find displacement using accelerometer and gyroscope. The problem I am facing is, when I rotate the acceleration data measured in body frame to the earth or initial frame ...
72 views

### CFD implementation in software [closed]

I've been learning CFD theory for 4 months (which includes FEA, FDM AND FVM) and now I want to start running simulations. As a novice to CFD software, I would appreciate some advice on where to start, ...
18 views

### Methods for discriminate model characteristics

Reading this recent trend, I was wondering if there are available methods to detect the qualitative features of experimental data, in order to get some clue about how to model those data. For instance,...
132 views

### Methods for solving $x'=Ax+b$ for small, sparse, singular $A$

I am in the process of building a robotics physics engine. I have been using the Linear ODE $x' = Ax + b$ for the core of my physics integration, but have never found a really good solution method for ...
172 views

### Simple Simulation Examples in Computational Fluid Dynamics

I would like to incorporate a CFD topic in a project I currently have. The deadline is a little less than a month from now. Basically, what I would like to do is solve some equations and simulate ...
55 views

### Help understanding and implementing fast multipole method for N-body

I've been trying to understand the Fast Multipole Method but not really getting anywhere. It seems like the fastest mainstream N-body simulation algorithm, and I would like to implement it in an ...
80 views

### $(1+x^M)^{1/M}$ need to be able to calculate any order derivatives vs. $x$ and $M$ for $x\ge 0$ and $M\gt 2$

cannot delete my own question, so I try to overwrite it instead...
46 views

17 views

### Converting events with irregular arrival times into a continous signal (1st, 2nd and 3rd order)

I got events coming in at irregular intervals. From these I need to emit the number of events arrived and the expected first and second derivative over some specified measurement period P. So ...
85 views

### Simple java gravity simulation

I'm trying to write a class that uses Newton's law of Gravitation to work out the field of a planet. I've tested my code by inputting values for Earth, for purely vertical motion, so I should get g = -...
82 views

### How to model the mixing of two fluids in a container?

In the context of a research project of mine, I am faced with the difficult task of modeling the mixing of two fluids in a container. I would like to achieve the following: Given a container (...