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Standard formulations of smoothed particle hydrodynamics (SPH) are unable to resolve mixing at fluid boundaries. We use an error and stability analysis of the generalised SPH equations of motion to prove that this is due to two distinct…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 J. I. Read , T. Hayfield , O. Agertz

Varieties of energy-stable numerical methods have been developed for incompressible two-phase flows based on the Navier-Stokes-Cahn-Hilliard (NSCH) model in the Eulerian framework, while few investigations have been made in the Lagrangian…

Fluid Dynamics · Physics 2023-03-22 Xiaoyu Feng , Zhonghua Qiao , Shuyu Sun , Xiuping Wang

Smoothed Particle Hydrodynamics (SPH) is a frequently applied tool in computational astrophysics to solve the fluid dynamics equations governing the systems under study. For some problems, for example when involving asteroids and asteroid…

Instrumentation and Methods for Astrophysics · Physics 2023-11-20 Irina Sagert , Oleg Korobkin , Ingo Tews , Bing-Jyun Tsao , Hyun Lim , Michael J. Falato , Julien Loiseau

By comparing the response to external strains in metallic glasses and in Lenard-Jones glasses we find a quantitative universality of the fundamental plastic instabilities in the athermal, quasistatic limit. Microscopically these two types…

Soft Condensed Matter · Physics 2015-06-03 Ratul Dasgupta , Smarajit Karmakar , Itamar Procaccia

Non-spherical particles transported by an anisotropic turbulent flow preferentially align with the mean shear and intermittently tumble when the local strain fluctuates. Such an intricate behaviour is here studied for inertialess,…

Soft Condensed Matter · Physics 2022-12-27 Lorenzo Campana , Mireille Bossy , Jeremie Bec

Particle shifting techniques (PST) have been used to improve the accuracy of the Smoothed Particle Hydrodynamics (SPH) method. Shifting ensures that the particles are distributed homogeneously in space. This may be performed by moving the…

Fluid Dynamics · Physics 2022-03-15 Dinesh Adepu , Prabhu Ramachandran

In this paper we present results from a series of hydrodynamical tests aimed at validating the performance of a smoothed particle hydrodynamics (SPH) formulation in which gradients are derived from an integral approach. We specifically…

Instrumentation and Methods for Astrophysics · Physics 2016-11-09 R. Valdarnini

We formulate a perturbative approximation to gravitational instability, based on Lagrangian hydrodynamics in Newtonian cosmology. We take account of `pressure' effect of fluid, which is kinematically caused by velocity dispersion, to aim…

Astrophysics · Physics 2009-11-07 Masaaki Morita , Takayuki Tatekawa

Shear transformations (i.e., localised rearrangements of particles resulting in the shear deformation of a small region of the sample) are the building blocks of mesoscale models for the flow of disordered solids. In order to compute the…

Soft Condensed Matter · Physics 2015-06-24 Alexandre Nicolas , Francesco Puosi , Hideyuki Mizuno , Jean-Louis Barrat

The accuracy of Lagrangian point-particle models for simulation of particle-laden flows may degrade when the particle and fluid momentum equations are two-way coupled. In these cases the fluid velocity at the location of the particle, which…

Fluid Dynamics · Physics 2018-10-17 Mahdi Esmaily , Jeremy Horwitz

We present the smoothed-particle hydrodynamics implementation SPHGal, which combines some recently proposed improvements in GADGET. This includes a pressure-entropy formulation with a Wendland kernel, a higher order estimate of velocity…

Cosmology and Nongalactic Astrophysics · Physics 2014-07-30 Chia-Yu Hu , Thorsten Naab , Stefanie Walch , Benjamin P. Moster , Ludwig Oser

Adjoint-based shape optimization most often relies on Eulerian flow field formulations. However, since Lagrangian particle methods are the natural choice for solving sedimentation problems in oceanography, extensions to the Lagrangian…

Fluid Dynamics · Physics 2022-09-07 Luka Schlegel , Volker Schulz

The purpose of this paper is to examine the Lagrangian stochastic modeling of the fluid velocity seen by inertial particles in a nonhomogeneous turbulent flow. A new Langevin-type model, compatible with the transport equation of the drift…

Fluid Dynamics · Physics 2009-07-01 Boris Arcen , Anne Tanière

To simulate the dynamics of fluid with polydisperse particles on macroscale level, one has to solve hydrodynamic equations with several relaxation terms, representing momentum transfer from fluid to particles and vice versa. For small…

Most approaches in Lagrangian fluid dynamics simulations proceed from the definition of particle volumes, from which discrete versions of the spatial differential operators are derived. Recently, Gallou\"et and M\'erigot [1] simultaneously…

Fluid Dynamics · Physics 2023-01-25 Daniel Duque

There has been interest in recent years to assess the ability of astrophysical hydrodynamics codes to correctly model the Kelvin-Helmholtz instability. Smoothed particle hydrodynamics (SPH), in particular, has received significant…

Instrumentation and Methods for Astrophysics · Physics 2019-09-10 Terrence S. Tricco

In this book chapter we describe the {\em Lagrangian} numerical relativity code \sphi. This code evolves spacetimes in full General Relativity by integrating the BSSN equations on structured meshes with a simple dynamical mesh refinement…

General Relativity and Quantum Cosmology · Physics 2024-05-22 S. Rosswog , P. Diener

We present approaches for the study of fluid-structure interactions subject to thermal fluctuations. A mixed mechanical description is utilized combining Eulerian and Lagrangian reference frames. We establish general conditions for…

Soft Condensed Matter · Physics 2023-02-28 Paul J. Atzberger

We investigate through numerical simulations the hydrodynamic interactions between two rigid spherical particles suspended on the axis of a cylindrical tube filled with an elastoviscoplastic fluid subjected to pressure-driven flow. The…

Propagation of elastic waves in damaged media (concrete, rocks) is studied theoretically and numerically. Such materials exhibit a nonlinear behavior, with long-time softening and recovery processes (slow dynamics). A constitutive model…

Classical Physics · Physics 2021-04-26 Harold Berjamin , Bruno Lombard , Guillaume Chiavassa , Nicolas Favrie