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We provide introductory explanations and illustrations of the $N$-body hydrodynamics code Charm N-body GrAvity solver (ChaNGa). ChaNGa simulates the gravitational motion and gas dynamics of matter in space, with the goal of modeling…

Instrumentation and Methods for Astrophysics · Physics 2023-06-07 J. W. Powell , L. Caudill , O. Young

This work discusses the correct modeling of the fully nonlinear free surface boundary conditions to be prescribed in water waves flow simulations based on potential flow theory. The main goal of such a discussion is that of identifying a…

Numerical Analysis · Mathematics 2023-06-06 Andrea Mola , Nicola Giuliani , Óscar Crego , Gianluigi Rozza

Multifluid simulations of plasma sheaths are increasingly used to model a wide variety of problems in plasma physics ranging from global magnetospheric flows around celestial bodies to plasma-wall interactions in thrusters and fusion…

Plasma Physics · Physics 2021-02-03 Petr Cagas , Ammar Hakim , Bhuvana Srinivasan

We discuss the relationship between the boundary conditions of the Schwinger-Dyson equations and the phase diagram of a bosonic field theory or matrix model. In the thermodynamic limit, many boundary conditions lead to the same solution,…

High Energy Physics - Theory · Physics 2007-05-23 Zachary Guralnik

We present a computational method to solve the magnetohydrodynamic equations in spherical geometry. The technique is fully nonlinear and wholly spectral, and uses an expansion basis that is adapted to the geometry: Chandrasekhar-Kendall…

Fluid Dynamics · Physics 2009-11-11 P. D. Mininni , D. C. Montgomery

We show how to use boundary conditions to drive the evolution on a Quantum Mechanical system. We will see how this problem can be expressed in terms of a time-dependent Schr\"{o}dinger equation. In particular we will need the theory of…

Quantum Physics · Physics 2015-10-28 J. M. Pérez-Pardo , M. Barbero-Liñán , A. Ibort

We propose a new Nitsche-type approach for weak enforcement of normal velocity boundary conditions for a Lagrangian discretization of the compressible shock-hydrodynamics equations using high-order finite elements on curved boundaries.…

Numerical Analysis · Mathematics 2023-09-06 Nabil M. Atallah , Vladimir Z. Tomov , Guglielmo Scovazzi

In the present study, a characteristic-based boundary condition scheme is developed for the compressible magnetohydrodynamic (MHD) equations in the general curvilinear coordinate system, which is an extension of the characteristic boundary…

Computational Physics · Physics 2023-10-24 P. Makaremi-Esfarjani , A. Najafi-Yazdi

Three-dimensional hydrodynamic simulations are commonly used to study the evolution of the gaseous content in isolated galaxies, besides its connection with galactic star formation histories. Stellar winds, supernova blasts, and black hole…

Astrophysics of Galaxies · Physics 2023-02-10 Anderson Caproni , Gustavo A. Lanfranchi , Amâncio C. S. Friaça , Jennifer F. Soares

In this article we develop a theoretical framework to study the hydrodynamic interactions in the presence of a non-flat and no-slip boundary. We calculate the influence of a small amplitude and sinusoidal deformations of a boundary wall in…

Soft Condensed Matter · Physics 2015-05-20 Somaye Hosseini Rad , Ali najafi

We analyze the role of boundary geometry in viscous electronic hydrodynamics. We address the twin questions of how boundary geometry impacts flow profiles, and how one can engineer boundary conditions -- in particular the effective slip…

Mesoscale and Nanoscale Physics · Physics 2019-11-11 Roderich Moessner , Nicolás Morales--Durán , Piotr Surówka , Piotr Witkowski

Immersed boundary methods are extensively used for simulations of dynamic solid objects interacting with fluids due to their computational efficiency and modelling flexibility compared to body-fitted grid methods. However, thin geometries,…

Fluid Dynamics · Physics 2022-03-14 Marin Lauber , Gabriel D. Weymouth , Georges Limbert

We present a new approach to Eulerian computational fluid dynamics that is designed to work at high Mach numbers encountered in astrophysical hydrodynamic simulations. The Eulerian fluid conservation equations are solved in an adaptive…

Astrophysics · Physics 2009-11-10 Hy Trac , Ue-Li Pen

Boundary conditions dictate how fluids, including liquid crystals, flow when pumped through a channel. Can boundary conditions also be used to control internally driven active fluids that generate flows spontaneously? By using numerical…

Soft Condensed Matter · Physics 2022-09-13 Paarth Gulati , Suraj Shankar , M. Cristina Marchetti

Multiscale modelling aims to systematically construct macroscale models of materials with fine microscale structure. However, macroscale boundary conditions are typically not systematically derived, but rely on heuristic arguments,…

Dynamical Systems · Mathematics 2019-11-18 Chen Chen , A. J. Roberts , J. E. Bunder

Motivated by recent theoretical work on tidal disruption events and other peculiar transients, we present moving-mesh radiation-hydrodynamic simulations of radiative luminosity emitted by a central source being reprocessed by a wind-like…

Solar and Stellar Astrophysics · Physics 2021-08-11 Diego Calderón , Ondřej Pejcha , Paul C. Duffell

We study the pattern dynamics in a reaction diffusion model of the activator--inhibitor type in the oscillatory regime. We consider finite systems with partially absorptive boundary conditions analizing examples in different geometries in…

Statistical Mechanics · Physics 2007-05-23 S. Bouzat , H. S. Wio

In this paper we argue that boundary condition may run with energy scale. As an illustrative example, we consider one-dimensional quantum mechanics for a spinless particle that freely propagates in the bulk yet interacts only at the origin.…

High Energy Physics - Theory · Physics 2013-01-29 Satoshi Ohya , Makoto Sakamoto , Motoi Tachibana

We undertake a general study of the boundary (or edge) modes that arise in gauge and gravitational theories defined on a space with boundary, either asymptotic or at finite distance, focusing on efficient techniques for computing the…

High Energy Physics - Theory · Physics 2023-05-17 Seolhwa Kim , Per Kraus , Richard M. Myers

Many micro-swimmers propel themselves by rotating micro-cylindrical organelles such as flagella or cilia. These cylindrical organelles almost never live in free space, yet their motions in a confining geometry can be counter-intuitive. For…

Fluid Dynamics · Physics 2023-12-25 Hanliang Guo , Yi Man , Hai Zhu