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This work numerically investigates the effects of two square bars placed in various arrangements in a channel on pressure drop and heat transfer. Tandem arrangements and the two bars arranged side by side to the approaching flow are considered. The separation distance between the bars is varied in both types of arrangements. The Reynolds number Re based on channel height is 10⁴, whereas the bar height to channel height (d/H) is 0.152. The channel walls are subjected to a constant wall temperature. The k‐ε turbulence model was used in conjunction with the Reynolds‐averaged momentum and energy equations for the simulations. A finite volume technique with staggered grids combined with the SIMPLEC algorithm is applied with a fine grid resolution. Results show that the local and global Nusselt numbers on the channel walls are strongly increased by the unsteady vortex shedding induced by the bars.

This study aims at investigating two-dimensional laminar flow of power-law fluids around three unconfined side-by-side cylinders.

The numerical study is performed by solving the governing (continuity and momentum) equations using a finite volume-based code ANSYS Fluent. The numerical results have been presented for different combinations of the governing dimensionless parameters (dimensionless spacing, 1.2 = L = 4; Reynolds number, 0.1 = Re = 100; power-law index, 0.2 = n = 1.8). The dependence of the kinematic and macroscopic characteristics of the flow such as streamline patterns, distribution of the surface pressure coefficient, total drag coefficient with its components (pressure and friction) and total lift coefficient on these dimensionless parameters has been discussed in detail.

It is found that the separation of the flow and the apparition of the wake region accelerate as the dimensionless spacing decreases, the number of the cylinder increases and/or the fluid behavior moves from shear-thinning to Newtonian then to shear-thickening behavior. In addition, the distribution of the pressure coefficient on the surface of the cylinders presents a complex dependence on the fluid behavior index and Reynolds number when the dimensionless spacing between two adjacent cylinders is varied. At low Reynolds numbers, the drag coefficient of shear-thinning fluids is stronger than that of Newtonian fluids; this tendency decreases progressively with increasing of Re until a critical value; beyond the critical Re, the opposite trend is observed. The lift coefficient of the middle cylinder is null, whereas, the exterior cylinders experience opposite lift coefficients, which show a complex dependence on the dimensionless spacing, the Reynolds number and the power-law index.

The flow over bluff bodies is a practical engineering problem. In the literature, it can be seen that the previous studies on non-Newtonian fluids are limited to the flow over one or two cylinders (effect of an odd number of cylinders on each other). Besides that, the available results concerning the flow of Newtonian fluids over three cylinders are limited to the high Reynolds numbers region only. However, this work treats the flow of non-Newtonian power-law fluids past three circular cylinders in side-by-side arrangements under a wide range of Re. The outcome of the present study demonstrates that the augmentation of the geometry complexity to three cylinders (effect of pair surrounding cylinders on the surrounded ones in what concerns Von Karman Street phenomenon) causes a drastic change in the flow patterns and in the macroscopic characteristics. The present results may be used to predict the flow behavior around multiple side-by-side cylinders.

The analysis of the flow field and heat transfer around a tube row or tube banks wrapped with porous layer have many related engineering applications. Examples include the reactor safety analysis, combustion, compact heat exchangers, solar power collectors, high-performance insulation for buildings and many another applications. The purpose of this paper is to perform a numerical study on flows passing through two circular cylinders in side-by-side arrangement wrapped with a porous layer under the influence of a magnetic field. The authors focus the attention to the effects of magnetic field, Darcy number and pitch ratio on the mechanism of convection heat transfer and flow structures.

The Darcy-Brinkman-Forchheimer model for simulating the flow in porous medium along with the Maxwell equations for providing the coupling between the flow field and the magnetic field have been used. Equations with the relevant boundary conditions are numerically solved using a finite volume approach. In this study, Stuart and Darcy numbers are varied within the range of 0 < N < 3 and 1e-6 < Da < 1e-2, respectively, and Reynolds and Prandtl numbers are equal to Re=100 and Pr=0.71, respectively.

The results show that the drag coefficient decreases for N < 0.6 and increases for N > 0.6. Also, the effect of magnetic field is negligible in the gap between two cylinders because the magnetic field for two cylinders counteracts each other in these regions.

To the authors knowledge, in the open literature, flow passing over two circular cylinders in side-by-side arrangement wrapped with a porous layer has been rarely investigated especially under the influence of a magnetic field.

The purpose of this paper is to investigate the laminar flow and heat transfer characteristics in a two‐dimensional horizontal channel with two square blocks placed side‐by‐side using a numerical scheme based on a coupling between the lattice Boltzmann method and the finite difference method.

The multiple‐relaxation‐time (MRT) lattice Boltzmann equation model coupled with the finite difference method are used to predict numerically the velocity and the temperature fields.

A complex structure of the fluid flow was observed for various dimensionless block separation distance (G). An unsteady flow was found when the two blocks are placed side by side (G = 0). For G < 1.5, the presence of each block develops the street of Van Karman which generates complex binary vortex street. In the opposite case (G > 1.5), the effect of this parameter (G) on the fluid is reduced, whereas, the distance between the blocks and the nearest walls have a great influence on the fluid flow and the heat transfer. When the obstacles are posed on the walls (G = 3), an important heat exchange between the blocks and the nearest walls is noted.

This study offers more knowledge on natural convection in an obstructed channel. Furthermore, this work shows the effectiveness of the MRT lattice Boltzmann equation model for this kind of geometry.

EACH September the eyes of the aeronautical World turn towards the S.B.A.C. Air Display and Exhibition with interest unequalled by any other event. It is fitting that the Display is now held each year at the airfield of the Royal Aircraft Establishment, one of the world's most prominent aeronautical research centres. This interest becomes increasingly keen too, as the preview day comes closer, because new prototypes of unorthodox designs often appear a short time before the Show to illustrate the results of years of careful planning, development and research of the particular company. These designs often mould the path of progress for smaller countries without the economic resources to forge the way ahead alone. Most British citizens are very proud of their country's place in aviation today, both in the military and civil fields. This is understood by most foreigners because it is clear that Britain has won a place in aeronautical development second to none.

THIS article attempts to summarize the technical development of two‐seater sailplanes during the past thirty years. There is no attempt to contribute anything new to the art, but only to bring together information from various sources. It is also hoped that the data collected will be found useful to designers.

Advances an alternative method of analysing the market price of leasehold investments for use when assessing the market price of a comparable investment. The method can be adapted to evaluate investment worth by substituting rental growth forecasts for those implied by market price levels. Baum and Crosby highlighted the inadequacy of current dual rate valuation methods for leasehold investments and the problems associated with the contemporary approach. Their work is used as the basis for this article. A discounted cash flow (DCF) approach is developed using an analysis of target returns. The all risks yield (ARY) and target return are first assessed on the basis that the investment is freehold but otherwise identical. The implied annual growth rate in CRV is then calculated using the equated yield formula. It is then argued, that because this growth in CRV arises from the location and quality of the building, it is equally applicable to a leasehold interest in that building. This leaves only the target return for the leasehold interest to be established, for a DCF valuation to be possible. Market transactions in leasehold properties are analysed in terms of target return to illustrate how statistical evidence of market sentiment can be accumulated. This evidence is based on the “extra return” required for leasehold investments over comparable freeholds. It will be shown that this “extra return” requirement is not materially affected by the freehold target return initially selected in order to carry out the analysis. The method accordingly appears reliable.

The Government have decided that the Scientific Civil Service is to be reorganized. They are deeply conscious of the contribution made by science towards the winning of the war, a contribution which may have altered the whole course of the war and has certainly shortened its duration. They are equally conscious of the contribution which science can make during peace to the efficiency of production, to higher standards of living, to improved health, and to the means of defence. They are resolved that the conditions of service for scientists working for the Government shall be such as to attract into the Civil Service scientifically qualified men and women of high calibre, and to enable them after entry to make the best use of their abilities, in order that scientists in the Government Service may play their full part in the development of the nation's resources and the promotion of the nation's well‐being.

This paper aims to study the fluid flow and forced convection heat transfer from an isothermal circular cylinder with control rods in the laminar unsteady flow regime.

The overset grid method was used for accurate simulation of the unsteady flows around different arrangements of the cylinders. Grid generation for overset grids was performed using a general orthogonal boundary fitted coordinate system. The method of solution was based on a finite volume discretization of the Navier-Stokes equations. Simulations were carried out for the Prandtl numbers of 0.7 and 7.0 with the Reynolds numbers ranging from 60 to 300.

The results indicate that the performance of multiple control rods depends strongly on the spacing ratio. Furthermore, in a manner similar to the flow patterns, four different thermal regimes were recognized based on the variations of mean Nusselt number versus G/D, as the thermal regimes follow the categories of flow regimes at different diameter ratios. However, for different Prandtl numbers, no single trend of heat transfer variation versus the spacing ratio exists for same regime.

Few studies have been conducted to investigate the heat transfer characteristics from control rods. The results of this study provide a comprehensive knowledge on the dynamical and thermal behavior of the flow around multiple cylinders.

The light two‐seat twin‐jet Microjet 200 made its first flight from Toulouse‐Blagnac on 24 June 1980. The aircraft flew for 40 minutes without problem, at an altitude of 1000 metres and a speed of 220 km/hr. Jacques Grangette was at the controls. A highly experienced team employed by Société Microturbo developed this aircraft. The team consists of around a dozen persons, including Jacques Grangette who is both leader of the team and in charge of development, Claude Fimbel, who conducted the study work and Jules Bernard, in charge of fabrication. Wind tunnel testing was executed at CEAT, Institut de Mécanique des Fluides de Lille (IMFL) for spin, and ONERA for flutter analysis.