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An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids

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Implicit atomistic viscosities in smoothed particle hydrodynamics.

Marco Ellero¹, Pep Español, Nikolaus A Adams

¹Lehrstuhl für Aerodynamik, Technische Universität München, 85747 Garching, Germany.

Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics

|January 15, 2011

Summary

This summary is machine-generated.

This study reveals that microscopic stress contributions significantly impact smoothed particle hydrodynamics (SPH) viscosity, especially in low-flow conditions. These atomistic effects, including kinetic and potential terms, are crucial for accurate simulations.

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Area of Science:

Computational physics
Fluid dynamics
Nonequilibrium statistical mechanics

Background:

Smoothed particle hydrodynamics (SPH) is a mesh-free Lagrangian method used for simulating fluid flow.
Standard analysis of transport coefficients in nonequilibrium molecular dynamics (NEMD) is well-established.
Previous work by Posch (1995) suggested nonzero microscopic contributions to stress in SPH.

Purpose of the Study:

To apply microscopic analysis of transport coefficients to SPH under steady-shear flow.
To investigate the contributions of kinetic and potential stress to the total stress tensor in SPH.
To understand the origin and impact of atomistic viscosities in SPH simulations.

Main Methods:

Microscopic analysis of transport coefficients.
Application to smoothed particle hydrodynamics (SPH) method.
Simulation under steady-shear flow conditions.

Main Results:

Observed nonzero microscopic (kinetic and potential) contributions to the total stress tensor in SPH.
Dissipative part of shear stress yields output viscosity matching input parameter.
Atomistic viscosities significantly contribute to the overall output viscosity, with kinetic part dominating at low viscous flows.

Conclusions:

Microscopic stress contributions are essential for accurate SPH viscosity calculations.
The kinetic stress contribution, acting as a Reynolds-like stress, is dominant in low-flow regimes.
SPH particle acceleration distributions show good agreement with experimental non-Gaussian statistics in the kinetic regime.