A WKB method was recently used to extend rapid distortion theory (RDT) to initially inhomogeneous turbulence strained by irrotational mean flows [S.V. Nazarenko, N. Kevlahan, B. Dubrulle, J. Fluid Mech. 390 (1999) 325]. This theory takes into account the feedback of turbulence on the mean flow, and it was used by Nazarenko et al. to explain the effect of strain reduction caused by turbulence ob...

The swirling motion of fluids that occurs irregularly in space and time is called turbulence. However, this randomness, apparent from a casual observation, is not without some order. Turbulent flows are as abundant in nature as life itself, and are pervasive in technology. They are a paradigm for spatially extended nonlinear dissipative systems in which many length scales are excited simultaneo...

When fluid flows through a channel, pipe, or duct, there are two basic forms of motion: smooth laminar motion and complex turbulent motion. The discontinuous transition between these states is a fundamental problem that has been studied for more than 100 yr. What has received far less attention is the large-scale nature of the turbulent flows near transition once they are established. We have c...

Purpose – The purpose of this paper is to investigate the geometric effects and pulsatile characteristics during the stenotic flows in tapering arteries. Design/methodology/approach – The low Reynolds number k ! turbulence model is applied to describe the stenotic flows in the tapering arteries in this paper. The results are divided into two sections. The first section characterizes the geometr...

A computational analysis of an annular converging-diverging (CD) and an altitude adaptive expansion-deflection (ED) nozzle is presented. Numerical results were generated using a 2D axisymmetric, pressure-coupled solver in conjunction with the Spalart-Allmaras turbulence closure model and second order spatial discretisation schemes. Results were recorded over a theoretical altitude range and com...

Our understanding of the dynamics of the Earth’s core can be advanced by a combination of observation, experiments, and simulations. A crucial aspect of the core is the interplay between the flow of the conducting liquid and themagnetic field this flow sustains via dynamo action. This non-linear interaction, and the presence of turbulence in the flow, precludes direct numerical simulation of th...

In nearly every area of fluid mechanics, our understanding is limited by the onset or presence of turbulence. Although recent years have seen a great increase in our physical understanding, a predictive theory of turbulent flow has not yet been established. Aside from certain results that can be derived through dimensional reasoning, it is still not possible to solve from first principles the s...

In an electrically conducting fluid two types of turbulence with a preferred direction are distinguished: planar turbulence, in which every velocity of the turbulent ensemble of flows has no component in the given direction; and two-dimensional turbulence, in which every velocity in the turbulent ensemble is invariant under translation in the preferred direction. Under the additional assumption...

A numerical simulation has been performed of the disturbed flow through and over a twodimensional array of rectangular buildings immersed in a neutrally stratified deep roughwalled turbulent boundary-layer flow. The model used for the simulation was the steady-state Reynolds-averaged Navier-Stokes equations with linear and non-linear eddy viscosity formulations for the Reynolds stresses. The ed...