Simon D. Harris, Derek B. Ingham and Ioan Pop
The purpose of this paper is to present a numerical and an analytical study of the fluid flow and heat transfer in the unsteady, laminar boundary layer resulting from the forced…
Abstract
Purpose
The purpose of this paper is to present a numerical and an analytical study of the fluid flow and heat transfer in the unsteady, laminar boundary layer resulting from the forced convection flow along a semi‐infinite wedge, where the transients are initiated at time t¯ = 0 when the wedge is impulsively started from rest with a uniform velocity and a constant heat flux at the walls of the wedge is suddenly imposed.
Design/methodology/approach
The velocity of the main free stream is written in non‐dimensional form for t > 0 as ue(x) = xm, where x is the non‐dimensional distance along the surface from the leading edge (apex) of the wedge and the constant m is related to the included angle of the wedge πβ by m = β / (2 − β) (0 ≤ m ≤ 1 for physical applications). The wedge and the fluid are assumed to be initially (t¯ = 0) at the same uniform temperature T∞, so that there is zero heat flux at the surface. A time‐dependent thermal boundary layer is then produced at t¯ = 0 as the zero heat flux at the surface is suddenly changed, and a constant heat flux qw is imposed as the wedge is set into motion. Analytical solutions for the simultaneous development of the momentum and thermal boundary layers are obtained for both small (initial unsteady flow) and large (steady‐state flow) times for several wedge angles (several values of m) and several values of the Prandtl number Pr. These two asymptotic solutions are matched using two specialised numerical procedures.
Findings
The numerical results obtained for the transient fluid velocity and temperature fields concentrate mainly on the case when the Prandtl number Pr = 1 and m = 1 / 5, namely a wedge angle of 60○. Required alterations to these parameters are then discussed with reference to variations in Pr and m separately. Further, an engineering empirical expression is presented for the skin friction Cf (τ) Rex1/2 that is valid for all times. The comparison between the empirical formula and the full numerical solution demonstrates that this matching solution can be used with confidence over the whole range of values of the non‐dimensional time τ for each of the values of m presented, and may therefore be used with confidence in engineering applications.
Originality/value
The results of the present work, which have been obtained through many computations, are very important for the advancement of knowledge on this classical problem of fluid mechanics and heat transfer. It is believed that such very detailed solutions have not previously been presented.
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This chapter investigates the nature of the transformation of macroeconomics by focusing on the impact of the Great Depression on economic doctrines. There is no doubt that the…
Abstract
This chapter investigates the nature of the transformation of macroeconomics by focusing on the impact of the Great Depression on economic doctrines. There is no doubt that the Great Depression exerted an enormous influence on economic thought, but the exact nature of its impact should be examined more carefully. In this chapter, I examine the transformation from a perspective which emphasizes the interaction between economic ideas and economic events, and the interaction between theory and policy rather than the development of economic theory. More specifically, I examine the evolution of what became known as macroeconomics after the Depression in terms of an ongoing debate among the “stabilizers” and their critics. I further suggest using four perspectives, or schools of thought, as measures to locate the evolution and transformation; the gold standard mentality, liquidationism, the Treasury view, and the real-bills doctrine. By highlighting these four economic ideas, I argue that what happened during the Great Depression was the retreat of the gold standard mentality, the complete demise of liquidationism and the Treasury view, and the strange survival of the real-bills doctrine. Each of those transformations happened not in response to internal debates in the discipline, but in response to government policies and real-world events.
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Malcolm B. Coate and Mark D. Williams
This paper generalizes the critical loss concept of Harris and Simons to account for a broader range of possible cost structures. Our analysis presents a specialized market-level…
Abstract
This paper generalizes the critical loss concept of Harris and Simons to account for a broader range of possible cost structures. Our analysis presents a specialized market-level equilibrium for a relatively homogeneous good in which the Harris and Simons’ critical loss structure is appropriate for market definition. Then, we broaden the equilibrium and propose a generalized critical loss analysis. Of course, for relatively differentiated goods, market definition analysis would use firm-level modeling and therefore the standard market-level critical loss modeling could be inappropriate.
Barrie O. Pettman and Richard Dobbins
This issue is a selected bibliography covering the subject of leadership.
Abstract
This issue is a selected bibliography covering the subject of leadership.
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This bibliography is offered as a practical guide to published papers, conference proceedings papers and theses/dissertations on the finite element (FE) and boundary element (BE…
Abstract
This bibliography is offered as a practical guide to published papers, conference proceedings papers and theses/dissertations on the finite element (FE) and boundary element (BE) applications in different fields of biomechanics between 1976 and 1991. The aim of this paper is to help the users of FE and BE techniques to get better value from a large collection of papers on the subjects. Categories in biomechanics included in this survey are: orthopaedic mechanics, dental mechanics, cardiovascular mechanics, soft tissue mechanics, biological flow, impact injury, and other fields of applications. More than 900 references are listed.
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GARY D. HOLT, PAUL O. OLOMOLAIYE and FRANK C. HARRIS
The procedural and administrative aspects of UK tendering have remained largely unaltered for decades but this may soon change in light of the recent review of the construction…
Abstract
The procedural and administrative aspects of UK tendering have remained largely unaltered for decades but this may soon change in light of the recent review of the construction sector, headed by Sir Michael Latham. This paper presents findings of a nationwide survey of UK construction contractors assessing their opinion of the Latham procurement recommendations, along with their opinion of the authors' proposals for alternative selection procedure. Contractor usage/opinion of current tendering methods, tendering documentation and contractual arrangements are also identified. Analysis techniques primarily involve the derivation of contractor preference, agreement and importance indices (Pri, Agi and Imi respectively). Results show that clients are attempting to cut costs by increased use of open tendering coupled with plan and specification tender documentation, but that savings are offset by clients ultimately paying for contractors' costs associated with their achieving contract award for only 1 in 5 bids. Generally, contractors are in tune with the ideals of the Latham review and characteristics pertaining to the HOLT (Highlight Optimum Legitimate Tender) selection technique.