A new and very general technique for simulating solid-fluid suspensions is described; its most important feature is that the computational cost scales linearly with the number of particles. The method combines Newtonian dynamics of the solid particles with a discretized Boltzmann equation for the fluid phase; the many-body hydrodynamic interactions are fully accounted for, both in the creeping-...

A shear-improved Smagorinsky model is introduced based on recent results concerning shear effects in wall-bounded turbulence by Toschi et al. (2000). The Smagorinsky eddyviscosity is modified as νT = (Cs∆) (|S|−|〈S〉|): the magnitude of the mean shear |〈S〉| is subtracted to the magnitude of the instantaneous resolved strain-rate tensor |S|; here CS is the standard Smagorinsky constant and ∆ deno...

Turbulence is inherently a three-dimensional and time dependent flow phenomenon (Pope, 2001). Because of the ubiquitous existence turbulent flows in nature, accurate characterization flows, either through experimental measurements or direct numerical simulations, paramount importance for modeling turbulence (Liu Katz, 2018). Since its inception 1984 (Adrian, 1984), Particle Image Velocimetry (P...

A review of existing basic turbulence modeling approaches reveals the need for the development of unified turbulence models which can be used continuously as filter density function (FDF) or probability density function (PDF) methods, large eddy simulation (LES) or Reynolds-averaged Navier–Stokes (RANS) methods. It is then shown that such unified stochastic and deterministic turbulence models c...

Aims. We study the dependence of turbulent transport coefficients, such as α effect and turbulent magnetic diffusivity, on shear and magnetic Reynolds number in the presence of helical forcing. Methods. We use three-dimensional direct numerical simulations with periodic boundary conditions and measure turbulent transport coefficients using the kinematic test field method. In all cases the magne...

A direct numerical simulation database of bubbly channel flows at friction Reynolds number 180 and with three different global void fractions has been used to perform a multiscale analysis the anisotropy stress tensor, dissipation subgrid-scale (SGS) tensor in order characterize turbulence for wide range scales down smallest structures occurring flow. Based on hypothesis Kolmogorov, non-linear ...

PURPOSE This study aims to present flow control over the backward-facing step with specially designed right-angle-shaped plasma actuator and analyzed the influence of various scales of flow structures on the Reynolds stress through snapshot proper orthogonal decomposition (POD). METHODS 2D particle image velocimetry measurements were conducted on region (x/h = 0-2.25) and reattachment zone in...

Flat plate skin friction calculations over a range of Mach numbers from 0.4 to 3.5 at Reynolds numbers from 16 million to 492 million using a Navier Stokes method with advanced turbulence modeling are compared with incompressible skin friction coefficient correlations. The semi-empirical correlation theories of van Driest; Cope; Winkler and Cha; and Sommer and Short T’ are used to transform the...

We investigate the nonlinear dynamics of turbulent shear flows, with and without rotation, in the context of a simple but physically motivated closure of the equation governing the evolution of the Reynolds stress tensor. We show that the model naturally accounts for some familiar phenomena in parallel shear flows, such as the subcritical transition to turbulence at a finite Reynolds number and...

Reynolds-averaged Navier–Stokes (RANS) models are known to be inaccurate in complex flows, for instance, laminar-turbulent transition, and RANS uncertainty quantification (UQ) is essential estimate the their predictions. In this study, a recent physics-based UQ framework that introduces eigenvalue, eigenvector, turbulence kinetic energy perturbations modeled Reynolds stress tensor has been used...