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The ultimate goal of a sound theory of turbulence in fluids is to close in a rational way the Reynolds equations, namely to express the tensor of turbulent stress as a function of the time average of the velocity field. Based on the idea…

Fluid Dynamics · Physics 2021-07-14 Yves Pomeau , Martine Le Berre

The theory of turbulent diffusion of chemically reacting gaseous admixtures developed previously (Phys. Rev. E {\bf 90}, 053001, 2014) is generalized for large yet finite Reynolds numbers, and the dependence of turbulent diffusion…

Fluid Dynamics · Physics 2018-05-24 T. Elperin , N. Kleeorin , M. Liberman , A. Lipatnikov , I. Rogachevskii , R. Yu

The role of polymers additives on the turbulent convective flow of a Rayleigh--Taylor system is investigated by means of direct numerical simulations (DNS) of Oldroyd-B viscoelastic model. The dynamics of polymers elongation follow…

Chaotic Dynamics · Physics 2015-05-27 G. Boffetta , A. Mazzino , S. Musacchio

The Rayleigh number $Ra$ dependence of the Nusselt number $Nu$ in turbulent Rayleigh--B\'enard convection is numerically investigated for a moderate and low Prandtl number, $Pr=0.7$ and $0.021$, respectively. Here we specifically address…

Fluid Dynamics · Physics 2019-06-18 Marten Klein , Heiko Schmidt

The effects of compressibility on Rayleigh-Taylor instability (RTI) are investigated by inspecting the interplay between thermodynamic and hydrodynamic non-equilibrium phenomena (TNE, HNE, respectively) via a discrete Boltzmann model (DBM).…

Soft Condensed Matter · Physics 2016-02-26 Huilin Lai , Aiguo Xu , Guangcai Zhang , Yanbiao Gan , Yangjun Ying , Sauro Succi

We study turbulent flows in planar channels with unstable thermal stratification, using direct numerical simulations in a wide range of Reynolds and Rayleigh numbers and reaching flow conditions which are representative of asymptotic…

Fluid Dynamics · Physics 2017-06-28 Sergio Pirozzoli , Matteo Bernardini , Roberto Verzicco , Paolo Orlandi

Rayleigh-Taylor instability (RTI) occurs at the interface of two media when the heavier fluid is accelerated into the lighter fluid and is a prototypical hydrodynamic event present in many physical events. In high energy physics, this…

Fluid Dynamics · Physics 2022-03-03 Prasannabalaji Sundaram , Aditi Sengupta , Tapan K. Sengupta

We consider the evolution of two incompressible fluids with homogeneous densities $\rho_-<\rho_+$ subject to gravity described by the inviscid Boussinesq equations and provide the explicit relaxation of the associated differential…

Analysis of PDEs · Mathematics 2022-01-24 Björn Gebhard , József J. Kolumbán

We assess experimentally the scaling laws that characterize the mixing region produced by the Rayleigh-Taylor instability in a confined porous medium. In particular, we wish to assess experimentally the existence of a superlinear scaling…

Fluid Dynamics · Physics 2024-08-02 Marco De Paoli , Diego Perissutti , Cristian Marchioli , Alfredo Soldati

Rayleigh-Taylor instabilities (RTI) play an important role in the evolution of inertial confinement fusion (ICF) processes, while analytical prediction of the RTI growth rate often fails to reach an agreement with the experimental and…

Plasma Physics · Physics 2024-08-21 Y. Guo , D. Wu , J. Zhang

We present results from numerical simulations of Rayleigh-Taylor turbulence, performed using a recently proposed lattice Boltzmann method able to describe consistently a thermal compressible flow subject to an external forcing. The method…

Fluid Dynamics · Physics 2015-05-20 A. Scagliarini , L. Biferale , M. Sbragaglia , K. Sugiyama , F. Toschi

This study explores heat and turbulent modulation in three-dimensional multiphase Rayleigh-B\'enard convection using direct numerical simulations. Two immiscible fluids with identical reference density undergo systematic variations in…

Fluid Dynamics · Physics 2024-08-26 Abbas Moradi Bilondi , Nicolò Scapin , Luca Brandt , Parisa Mirbod

The effects of different initial density distributions on the evolution of buoyancy-driven homogeneous variable-density turbulence (HVDT) at low (0.05) and high (0.75) Atwood numbers are studied by using high-resolution direct numerical…

Fluid Dynamics · Physics 2020-04-06 Denis Aslangil , Daniel Livescu , Arindam Banerjee

Fluid turbulence is characterized by strong coupling across a broad range of scales. Furthermore, besides the usual local cascades, such coupling may extend to interactions that are non-local in scale-space. As such the computational…

The Eulerian advection-dispersion-reaction equation (ADRE) suffers the well-known scale-effect of reduced apparent reaction rates between chemically dissimilar fluids at larger scales (or dimensional averaging). The dispersion tensor in the…

Fluid Dynamics · Physics 2018-12-05 David A. Benson , Diogo Bolster , Stephen Pankavich

In this work, we first develop a general mesoscopic multiple-relaxation-time lattice Boltzmann (MRT-LB) model for the two-dimensional diffusion equation with the constant diffusion coefficient and source term, where the D2Q5 (five discrete…

Numerical Analysis · Mathematics 2023-08-11 Ying Chen , Zhenhua Chai , Baochang Shi

Rayleigh-Taylor-instability(RTI) induced flow and mixing are of great importance in both nature and engineering scenarios. To capture the underpinning physics, tracers are introduced to make a supplement to discrete Boltzmann simulation of…

Fluid Dynamics · Physics 2022-03-24 Ge Zhang , Aiguo Xu , Dejia Zhang , Yingjun Li , Huilin Lai , Xiaomian Hu

The Rayleigh--Taylor (RT) turbulence is investigated by means of high resolution numerical simulations. The main question addressed here is on whether RT phenomenology can be considered as a manifestation of universality of Navier--Stokes…

Chaotic Dynamics · Physics 2015-05-13 G. Boffetta , A. Mazzino , S. Musacchio , L. Vozella

Small-scale effects of turbulent mixing are numerically investigated by applying the map-based, stochastic, one-dimensional turbulence (ODT) model to confined planar jets. The model validation is carried out for the momentum transport by…

Fluid Dynamics · Physics 2019-04-19 Marten Klein , Christian Zenker , Heiko Schmidt

We study turbulent diffusion of chemically reacting gaseous admixtures in a developed turbulence. In our previous study [Phys. Rev. Lett. {\bf 80}, 69 (1998)] using a path-integral approach for a delta-correlated in time random velocity…

Fluid Dynamics · Physics 2014-11-19 Tov Elperin , Nathan Kleeorin , Michael Liberman , Igor Rogachevskii