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Initial conditions for (Newtonian) cosmological N-body simulations are usually set by re-scaling the present-day power spectrum obtained from linear (relativistic) Boltzmann codes to the desired initial redshift of the simulation. This…

Cosmology and Nongalactic Astrophysics · Physics 2017-06-28 Christian Fidler , Thomas Tram , Cornelius Rampf , Robert Crittenden , Kazuya Koyama , David Wands

We develop randomized quantum algorithms to simulate quantum collision models, also known as repeated interaction schemes, which provide a rich framework to model various open-system dynamics. The underlying technique involves composing…

Quantum Physics · Physics 2025-08-20 Kushagra Garg , Zeeshan Ahmed , Subhadip Mitra , Shantanav Chakraborty

The dynamical justifications which lie at the basis of an effective Statistical Mechanics for self gravitating systems are formulated, analyzing some among the well known obstacles thought to prevent a rigorous Statistical treatment. It is…

Astrophysics · Physics 2009-11-06 Piero Cipriani , Marco Pettini

Many exoplanetary systems are multiplanet configurations whose long-term dynamics are governed by N-body gravitational interactions. Consequently, their detection signatures cannot be adequately described by Keplerian orbits. Accurately…

Earth and Planetary Astrophysics · Physics 2026-04-13 Hong-Fei Jia , Sheng Jin , Dong-Hong Wu , Shang-Fei Liu

A new algorithm for numerical integration of the rigid-body equations of motion is proposed. The algorithm uses the leapfrog scheme and the quantities involved are angular velocities and orientational variables which can be expressed in…

Computational Physics · Physics 2016-09-08 Igor P. Omelyan

Topology optimization is concerned with the identification of optimal shapes of deformable bodies with respect to given target functionals. The focus of this paper is on a topology optimization problem for a time-evolving elastoplastic…

Analysis of PDEs · Mathematics 2021-06-21 Stefano Almi , Ulisse Stefanelli

We investigate a local incremental stationary scheme for the numerical solution of rate-independent systems. Such systems are characterized by a (possibly) non-convex energy and a dissipation potential, which is positively homogeneous of…

Numerical Analysis · Mathematics 2022-04-13 Merlin Andreia , Christian Meyer

We present a new time integrator for articulated body dynamics. We formulate the governing equations of the dynamics using only the position variables and recast the position-based articulated dynamics as an optimization problem. Our…

Robotics · Computer Science 2018-07-24 Zherong Pan , Dinesh Manocha

Symplectic integrators are a foundation to the study of dynamical $N$-body phenomena, at scales ranging from from planetary to cosmological. These integrators preserve the Poincar\'e invariants of Hamiltonian dynamics. The $N$-body…

Earth and Planetary Astrophysics · Physics 2019-10-09 David M. Hernandez

In a previous paper we introduced a new method for simulating collisional gravitational $N$-body systems with linear time scaling on $N$, based on the Multi-Particle Collision (MPC) approach. This allows us to simulate globular clusters…

Astrophysics of Galaxies · Physics 2022-03-04 Pierfrancesco Di Cintio , Mario Pasquato , Alicia Simon-Petit , Suk-Jin Yoon

This work proposes a novel variational approximation of partial differential equations on moving geometries determined by explicit boundary representations. The benefits of the proposed formulation are the ability to handle large…

Computational Engineering, Finance, and Science · Computer Science 2024-06-04 Santiago Badia , Pere A. Martorell , Francesc Verdugo

At early times dark matter has a thermal velocity dispersion of unknown amplitude which, for warm dark matter models, can influence the formation of nonlinear structure on observable scales. We propose a new scheme to simulate cosmologies…

Cosmology and Nongalactic Astrophysics · Physics 2020-06-10 Jens Stücker , Oliver Hahn , Raul E. Angulo , Simon D. M. White

We introduce and demonstrate the power of a method to speed up current iterative techniques for N-body modified gravity simulations. Our method is based on the observation that the accuracy of the final result is not compromised if the…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-12 Alexandre Barreira , Sownak Bose , Baojiu Li

Within this paper, we introduce partially and fully decoupled time stepping schemes for linear thermo-poroelasticity. This means that the mechanics, heat, and flow equations can be solved sequentially. We provide sufficient conditions on…

Numerical Analysis · Mathematics 2026-03-17 R. Altmann , R. Maier , J. Schmeck

We investigate the possibility of generating initial conditions for cosmological N-body simulations by simulating a system whose correlations at thermal equilibrium approximate well those of cosmological density perturbations. The system is…

Astrophysics · Physics 2009-11-10 M. Joyce , D. Levesque , B. Marcos

We report an accessible and robust tool for evaluating the effects of Coulomb collisions on a test particle in a plasma that obeys Maxwell-J\"uttner statistics. The implementation is based on the Beliaev-Budker collision integral which…

Plasma Physics · Physics 2018-01-17 Konsta Särkimäki , Eero Hirvijoki , Juuso Terävä

The body of work presented here revolves around the investigation of the existence and nature of extra-solar planetary systems. The fitting of stellar radial velocity time series data is attempted by constructing a model to quantify the…

Astrophysics · Physics 2017-02-13 Gur Windmiller , Don Short , Jerome Orosz

Calculating the long term solution of ordinary differential equations, such as those of the $N$-body problem, is central to understanding a wide range of dynamics in astrophysics, from galaxy formation to planetary chaos. Because generally…

Instrumentation and Methods for Astrophysics · Physics 2018-01-23 David M. Hernandez , Edmund Bertschinger

A time optimal attitude control problem is studied for the dynamics of a rigid body. The objective is to minimize the time to rotate the rigid body to a desired attitude and angular velocity while subject to constraints on the control…

Optimization and Control · Mathematics 2007-09-19 Taeyoung Lee , Melvin Leok , N. Harris McClamroch

The Euler equations associated with diffeomorphism groups have received much recent study because of their links with fluid dynamics, computer vision, and mechanics. In this paper, we consider the dynamics of $N$ point particles or `blobs'…

Chaotic Dynamics · Physics 2007-05-23 Robert I McLachlan , Stephen Marsland