All Questions
Tagged with computational-physics numerical-modelling
28
questions
1
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2
answers
142
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Numerical code to solve LLG is not preserving norm
I am new to this thread. I am trying to do a simple exercise on solving the LLG equation. The equation reads:
$\frac{d\vec{m}}{dt} = -\gamma(\vec{m} \times\vec{H})$.
Given a normalized input state ($...
- 11
1
vote
1
answer
584
views
RK4 integration of the three-bodies problem with C++
first of all thank you for all the answers you gave me yesterday for the integration via Symplectic Euler's method of the three-body problem.
We managed to implement both Euler's and Runge Kutta 4's ...
- 171
2
votes
1
answer
274
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Modelling a spring interpolation
I have parameters $T$ for tension, $b$ for bounciness and $P_t$ for target value that should be approached as t goes to infinity.
Currently I have written an equation like so:
$\ddot{f}(t)=\frac{T(P_t-...
- 23
3
votes
0
answers
71
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Looking for non-trivial examples of solutions to 3D wave equations?
We have developed a (new) numerical scheme to solve the classical wave equation in 3 dimensions and we aim to publish the results.
We can read in the aim and scope of the journal of computational and ...
- 151
2
votes
1
answer
152
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Numerical diagonalization of Hamiltonian
Framework
I am trying to diagonalize the Bogoliubov-de Gennes Hamiltonian. The problem is that the Hamiltonian contains a Laplacian. This could be solved by using a discretized Laplacian.
How I tried ...
- 21
0
votes
1
answer
677
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Can I use periodic boundary conditions for `U` but not for `p`?
Cross-posted from Stack Overflow. (https://stackoverflow.com/questions/70686368/can-i-use-periodic-boundary-conditions-for-u-but-not-for-p)
I am trying to numerically compute the drag force around a ...
- 51
1
vote
1
answer
171
views
Does the leap-frog algorithm conserve energy for n-body problems?
The leap-frog algorithm is able to conserve to a certain extent the energy of a system, which flucutates as a cosine around a stable value. Is this true if we apply the algorithm to a n-body ...
0
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0
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80
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How to distinguish primary hosts (stars) and orbiting satellites (planets) and tertiary bodies (moons) by their mass and trajectory?
I posted this question in the astronomy stackexchange. There are no responses, and it was suggested that I pose the question here. The "too long, didn't read" was taken from a comment, and ...
- 11
2
votes
2
answers
468
views
Generating particles from a distribution function using Monte Carlo
I have been given a 4D ($x, y, v_x, v_y$) distribution function, $f(x,y,v_x, v_y)$, generated by an external code. I want to generate a set of particles from this distribution function, say 10k ...
user38535
0
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1
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99
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Acoustic Simulation, how are boundaries handled?
I don't have a background in numerical modeling so this question is rather broad.
What I am interested in is modeling the propagation of an ultrasonic acoustic wave in 3d space. The basic 3d wave ...
- 133
0
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0
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54
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Unsteady Stokes equations in ALE framework
I'm trying to solve Unsteady Stokes equations on a moving domain, using an ALE formulation, that is
$$\frac{\partial \mathbf{u}}{\partial t} - \mathbf{w}\cdot \nabla\mathbf{u} = \nu\Delta\mathbf{u} - \...
- 11
1
vote
1
answer
75
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How long should the hyperelastic equations be solved before updating the mesh?
How long should the hyperelastic equations be solved before updating the mesh? To be specific, I'm interested in the hyperelastic model with a neo-Hookean solid:
$$
\nabla\cdot\sigma + f = \rho\ddot{...
- 767
3
votes
3
answers
406
views
What numerical methods are used to model deformations in elastic physics?
What numerical methods are used to model deformations in elastic physics? For example, here's an example of a hyperelastic deformation in Ansys:
Perhaps more simply than hyperelasticity, for linear ...
- 767
1
vote
2
answers
444
views
How to simulate over 1 billion particles?
I want to simulate human erythrocytes in capillaries. I calculated, that for a 1 meter long and 1 mm in diameter capillary there are about 3 billion blood cells.
Erythrocytes are actually discs, but ...
- 117
4
votes
2
answers
376
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Computational cost comparison of DNS and SPH
I may be incorrect, but it seems like commercial graphics codes typically use smoothed particle hydrodynamics (SPH) to produce stunning simulations and not continuum based methods. Why is this? Is SPH ...
