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We study theoretically and numerically spatial distribution and collision rate of droplets that sediment in homogeneous isotropic Navier-Stokes turbulence. It is assumed that typical turbulent accelerations of fluid particles are much…

Fluid Dynamics · Physics 2022-05-17 Itzhak Fouxon , Seulgi Lee , Changhoon Lee

We consider the long-standing problem of Rayleigh-Taylor instability with variable acceleration, and focus on the early-time dynamics of an interface separating incompressible ideal fluids of different densities subject to an acceleration…

Plasma Physics · Physics 2019-06-25 Des L. Hill , Aklant K. Bhowmick , Snezhana I. Abarzhi

{\bf Direct} transition from low Reynolds number "weak" Gaussian turbulence to fully developed "strong" turbulence at a critical Reynolds number $R^{tr}_{\lambda}\approx 8.91$ has recently been theoretically predicted and tested in high…

Fluid Dynamics · Physics 2019-07-01 victor Yakhot

If a fluid flow is driven by a weak Gaussian random force, the nonlinearity in the Navier-Stokes equations is negligibly small and the resulting velocity field obeys Gaussian statistics. Nonlinear effects become important as the driving…

Fluid Dynamics · Physics 2018-10-01 Jörg Schumacher , Ambrish Pandey , Victor Yakhot , Katepalli R. Sreenivasan

We demonstrate that special correlations in the initial conditions of freely evolving, homogeneous magnetohydrodynamic (MHD) turbulence can lead to the formation of enormous current sheets. These coherent structures are observed at the peak…

Fluid Dynamics · Physics 2015-06-18 Vassilios Dallas , Alexandros Alexakis

The multiplicity of routes from deterministic chaos to turbulence caused by the spontaneous breaking of the local reflectional symmetry in the flows induced by Rayleigh-Taylor instability has been studied using the notion of distributed…

Fluid Dynamics · Physics 2023-02-23 A. Bershadskii

A wide variety of astrophysical phenomena involve the flow of turbulent magnetized gas with relativistic velocity or energy density. Examples include gamma-ray bursts, active galactic nuclei, pulsars, magnetars, micro-quasars, merging…

High Energy Astrophysical Phenomena · Physics 2015-05-30 Jonathan Zrake , Andrew MacFadyen

The distribution functions of field fluctuations of the turbulent mixing layer produced by a Rayleigh-Taylor instability (RTI) have long been hypothesized to involve bimodal effects. The present work reviews existing quantitative and…

Fluid Dynamics · Physics 2024-11-26 R. Watteaux , J. A. Redford , A. Llor

We evaluate the effects of preequilibrium dynamics on observables in ultrarelativistic heavy-ion collisions. We simulate the initial nonequilibrium phase within A MultiPhase Transport (AMPT) model, while the subsequent near-equilibrium…

We consider the process of convective dissolution in homogeneous and isotropic porous media. The flow is unstable due to the presence of a solute that induces a density difference responsible for driving the flow. The mixing dynamics is…

Fluid Dynamics · Physics 2024-08-02 Marco De Paoli , Christopher J. Howland , Roberto Verzicco , Detlef Lohse

Turbulent characteristics within shear layer have been studied, recently, within vegetative canopy, buildings, dunes. Kevin-Helmholtz instability triggered hairpin vortex shedding has been widely concluded as the "signature" of mixing layer…

Fluid Dynamics · Physics 2020-03-16 Chao Wang , Ching Cheng

We first develop a new mathematical model for two-fluid interface motion, subjected to the Rayleigh-Taylor (RT) instability in two-dimensional fluid flow, which in its simplest form, is given by $ h_{tt}(\alpha,t) = A g\, \Lambda h -…

Analysis of PDEs · Mathematics 2016-07-06 Rafael Granero-Belinchón , Steve Shkoller

A wide range of natural and engineered fluid flows exhibit spatial or temporal viscosity variations, spanning scales from microbial locomotion to planetary mantle convection. These variations introduce qualitatively new physical mechanisms…

Fluid Dynamics · Physics 2025-08-01 Arjun Sharma , Ritabrata Thakur , Sharath Jose , Rama Govindarajan

The Richtmyer-Meshkov instability (RMI) occurs when a shock wave passes through an interface between fluids of different densities, a phenomenon prevalent in a variety of scenarios including supersonic combustion, supernovae, and inertial…

Fluid Dynamics · Physics 2024-04-15 Usman Rana , Thomas Abadie , David Chapman , Nathan Joiner , Omar Matar

The partially-averaged Navier-Stokes (PANS) equations are used to predict the variable-density Rayleigh-Taylor (RT) flow at Atwood number 0.5 and maximum Reynolds number $500$. This is a prototypical problem of material mixing featuring…

We study the large-scale helical vortex shedding regime in the wake of an axisymmetric body with a blunt trailing edge at high Reynolds numbers, both experimentally and by means of local, linear, spatiotemporal stability analysis. In the…

Fluid Dynamics · Physics 2019-12-17 Alejandro Sevilla , Carlos Martínez-Bazán

Results of direct numerical simulations and laboratory experiments have been used in order to show that the buoyancy driven bubbly flows at high gas volume fraction are mixed by deterministic chaos with typical exponential spectrum of the…

Fluid Dynamics · Physics 2022-04-29 A. Bershadskii

We present a numerical study of emulsions in homogeneous and isotropic turbulence at $Re_\lambda=137$. The problem is addressed via Direct Numerical Simulations (DNS), where the Volume of Fluid (VOF) is used to represent the complex…

Fluid Dynamics · Physics 2023-01-09 Marco Crialesi-Esposito , Marco Edoardo Rosti , Sergio Chibbaro , Luca Brandt

The Rayleigh-Taylor Instability (RTI) under multi-mode perturbation in compressible flow is probed via the Discrete Boltzmann Modeling (DBM) with tracers. The distribution of tracers provides clear boundaries between light and heavy fluids…

Fluid Dynamics · Physics 2022-10-28 Hanwei Li , Aiguo Xu , Ge Zhang , Yiming Shan

The effect of kinetic helicity (velocity--vorticity correlation) on turbulent momentum transport is investigated. The turbulent kinetic helicity (pseudoscalar) enters the Reynolds stress (mirrorsymmetric tensor) expression in the form of a…

Fluid Dynamics · Physics 2016-04-06 Nobumitsu Yokoi , Axel Brandenburg