Modelling the transitional boundary layer

Recent developments in the modelling of the transition zone in the boundary layer are reviewed (the zone being defined as extending from the station where intermittency begins to depart from zero to that where it is nearly unity). The value of using a new non-dimensional spot formation rate parameter, and the importance of allowing for so-called subtransitions within the transition zone, are both stressed. Models do reasonably well in constant pressure 2-dimensional flows, but in the presence of strong pressure gradients further improvements are needed. The linear combination approach works surprisingly well in most cases, but would not be so successful in situations where a purely laminar boundary layer would separate but a transitional one would not. Intermittency-weighted eddy viscosity methods do not predict peak surface parameters well without the introduction of an overshooting transition function whose connection with the spot theory of transition is obscure. Suggestions are made for further work that now appears necessary for developing improved models of the transition zone

Theoretical and Experimental Aspects of the Shock Structure Problem

Flow of rarefied gases - Shock wave structure proble

Manifest Criminality, Criminal Intent, and the Metamorphosis of Lloyd Weinreb

My colleague has had a revelation. Professor Lloyd Weinreb\u27s views about larceny have undergone a striking transformation in the last six months. As recently as May 1980, when he completed the preface to the third edition of his criminal law casebook, he held one set of views about The Carrier\u27s Case and The King v. Pear. In the article published in this issue, he advances a different set of views about the two cases he regards as so important. He gives us no hint about how or why he underwent his change of heart. His transformation warrants our attention, for by examining his conflicting positions, we shall come to appreciate another set of discontinuities – those that, despite Professor Weinreb\u27s views, in fact shape the history of larcen

Minimal composite equations and the stability of non-parallel flows

The stability of a laminar boundary layer has classically been analysed in terms of the solutions of the Orr-Sommerfeld equation, which assumes that the flow is parallel. The purpose of this paper is to summarize the principles underlying the work done by the authors on non-parallel flows. This work adopts an asymptotic approach that involves the formulation of what we shall call 'minimal composite equations' in the limit of large Reynolds numbers. These equations include every term that is important somewhere, and none that is important nowhere, 'importance' being defined in terms of errors to some prescribed order in the local Reynolds number. This approach leads to a hierarchy of stability equations of successively increasing accuracy, including, in the lowest order, an ordinary differential equation for similarity flows, a low-order parabolic partial differential equation in the next order, and finally a 'full nonparallel' equation which is equivalent to the parabolized stability (partial differential) equations of Bertolotti et al.1. The o.d.e., written here in similarity variables, is similar to but not identical with the Orr-Sommerfeld. Typical results from the present approach are given to illustrate the nature of the stability 'surface' derived from the present theory, and the accuracy of the computed amplitude distributions

Indian summer monsoon experiments

Eight major field experiments have been carried out so far addressing the Indian summer monsoon. While these experiments were international and the impetus was external till 1980, India's own monsoon programmes evolved since then. In this article, objectives and outcomes from some of these experiments are described. It is shown that monsoon experiments have contributed in several ways. Each experiment enhanced the infrastructure facilities in the country, brought together scientists from different organizations to a common platform and also injected new people in this field. A large amount of data have been generated and their analysis has led to better understanding of the summer monsoon and discovery of new phenomena

On The Center Sets and Center Numbers of Some Graph Classes

For a set $S$ of vertices and the vertex $v$ in a connected graph $G$, $\displaystyle\max_{x \in S}d(x,v)$ is called the $S$-eccentricity of $v$ in $G$. The set of vertices with minimum $S$-eccentricity is called the $S$-center of $G$. Any set $A$ of vertices of $G$ such that $A$ is an $S$-center for some set $S$ of vertices of $G$ is called a center set. We identify the center sets of certain classes of graphs namely, Block graphs, $K_{m,n}$, $K_n-e$, wheel graphs, odd cycles and symmetric even graphs and enumerate them for many of these graph classes. We also introduce the concept of center number which is defined as the number of distinct center sets of a graph and determine the center number of some graph classes