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The model of elastoviscoplastic medium is based on the concept of slip proposed by Batdorf and Budiansky. The conditions of slip on a slip plane take into account the dependence of tangential stresses on slip velocity. But when the viscosity is low, they are almost similar to the dry friction conditions. Under some assumptions we succeeded in integrating the plastic shear rates over all possible slip planes in case of arbitrary three‐dimensional stress state and obtained an expression for the plastic strain rate tensor.

The model of elastoplastic medium is based on the concept of slip proposed by Batdorf and Budiansky. The conditions of slip on a slip plane take into account “the local loading criterion”. Under some assumptions we succeeded in integrating the plastic shears over all possible slip planes in case of arbitrary three‐dimensional stress state and obtained an expression for the plastic strain tensor increments and the closed variant of the elastoplastic model, which turns out to be a variant of the plastic flow theory. The integration method proposed can be applied for establishing the links between local conditions and macroscopic equations, and for some other slip conditions too.

This paper aims to provide a detailed study on the influence of slip flow and thermal jump over mixed convection flow along an exponentially stretching surface. Also, impacts of suction/blowing, volumetric heat source/sink and velocity ratio parameter will be studied in this analysis.

The modeled governing equations for the assumed problem are dimensional nonlinear partial differential equations in nature. To reduce these equations, non-similar transformations are used to get the dimensionless nonlinear partial differential equations. Then, quasi-linearization technique is used to linearize these non-dimensional nonlinear partial differential equations. Finally, an implicit finite difference scheme is used to discretize the resulting equations.

The physical explanations are provided for the variations of various non-dimensional governing parameters over the velocity and temperature profiles. Also, the effects of these dimensionless parameters on skin friction coefficient and heat transfer rate are scrutinized in a manner which highlights their physical interpretation. The detailed discussion exhibits the fact that the streamwise co-ordinate velocity ratio parameter, partial slip parameter and the thermal jump parameter have significant influence over the flow and thermal fields.

This work has not been reported in the literature to the authors’ best of knowledge.

The purpose of the current research is to study the turbulent flow through microchannels having a micropost in aligned and staggered arrangements.

Numerical calculations are performed on the basis of the finite volume approach, which is based on the SIMPLEC algorithm. In this work, the slip velocity, flow velocity distribution and friction factor for the two micropost patterns are examined at friction Reynolds numbers of R_eτ = 395 and 590, relative module widths of W_m = 0.1 and 1 and cavity fraction range of F_c = 0.1 to 0.9.

Results reveal that for the two micropost patterns, as the friction Reynolds number, relative module width or cavity fraction increases, the slip velocity increases and friction factor decreases. It is found that the aligned micropost configuration leads to higher slip velocity and lower friction factor. Numerical findings indicate that the existence of the continuous cavity surface along the flow direction could be a significant criterion to realize if the velocity distribution deviates from that of the smooth channel. It is also shown that the turbulent flows are capable of producing more drag reduction than the laminar ones.

Previous studies have shown that microchannels consisting of a micropost pattern in aligned and staggered arrangements could be viewed as a promising alternative in the microscale flows for the heat removal purposes. Therefore, understanding the fluid flow through microchannels consisting of these configurations (which is a prerequisite to better understand thermal performance of such microchannels) is a significant issue, which is the subject of the present work.

According to the research, viscoplastic fluids are sensitive to slipping. The purpose of this study is to determine whether slip affects the Rayleigh–Bénard convection of viscoplastic fluids in cavities and, if so, under what conditions.

The wall slip was evaluated using a model created for viscoplastic (Bingham) fluids. The coupled conservation equations were solved numerically using the finite element method. Simulations were performed for various parameters: the Rayleigh number, yield number, slip yield number and friction number.

Wall slip determines two essential yield stresses: a specific yield stress value beyond which wall slippage is impossible (S_Yc); and a maximum yield stress beyond which convective flow is impossible (Y_c). At low Rayleigh numbers, Y_c is smaller than S_Yc. Hence, the flow attained a stable (conduction) condition before achieving the no-slip condition. However, for more significant Rayleigh numbers Y_c exceeded S_Yc. Thus, the flow will slip at low yield numbers while remaining no-slip at high yield numbers. The possibility of slipping on the wall increases the buoyancy force, facilitating the onset of Rayleigh–Bénard convection.

An essential aspect of this study lies in its comprehensive examination of the effect of slippage on the natural convection flow of viscoplastic materials within a cavity, which has not been previously investigated. This research contributes to a new understanding of the viscoplastic fluid behavior resulting from slipping.

The paper deals with the rheological‐dynamical analogy in which the three‐dimensional stress‐strain relations are defined under cyclic variation of stress for Hencky’s total strain theory. In many practical visco‐elasto‐plastic problems, like as multiaxial fatigue under loading at constant stress amplitude and constant stress ratio, the load‐carrying members are subjected to proportional loading. The classical Hencky’s theory has the advantage of mathematical convenience but its disadvantage is that the deformations predicted for the volume element are independent of the loading path. The existing formulations of the constitutive models for metals are mainly based on the Prandtl‐Reuss incremental theory of elasto‐plasticity, slip theory of plasticity or continuum damage mechanics. They have been shown capable of reproducing satisfactorily most experimental results available for metallic specimens. However, from the theoretical viewpoint little has been said about how these formulations relate to realistic predicting many different inelastic and time dependent problems of two‐ or threedimensional solids, such as fatigue, discontinuous plastic deformation etc. In this paper, fundamentally new aspect of isochronous constitutive relations for Hencky’s theory, which are dependent of the each loading path, is achieved by systematically introducing RDA concept into the continuum framework. Specific inelastic and fatigue formulation of triaxial state of stress is developed and discussed within the new theoretical tool and related to von Mises plasticity..

The purpose of this paper is to examine the initial mixing of wastewater discharged from submerged outfall diffusers and the influence of port configurations on wastewater distribution based on computational results.

Marine wastewater discharges from multiport diffusers are investigated by numerically solving three-dimensional and uncompressible two-phase flow fields. A mixture model simulates this flow and the standard k-e model to resolve flow turbulence; inter-phase interactions were described in terms of relative slip velocity between phases. Computations were performed for two values of the port spacings s/H with different current Froude numbers F.

Computational results compared well with previous laboratory measurements. Numerical results reveal that for both the closely spaced (s/H=0.21) and widely spaced (s/H=3.0) ports, the normalized dilution Sn becomes independent of F; further, the length of the near field xn and the spreading layer thickness hn are functions of F. For the closely spaced ports, the wastewater discharge behaves like a line plume, the Coanda effect is obvious, quasi-bifurcation is present, horseshoe structures of the jets in the planes are rapidly produced and then squashed and elongated, and the jet trajectories based on maximum velocity precede those based on maximum concentration. For the widely spaced ports, the wastewater discharge behaves like a point plume, the Coanda effect is not obvious, bifurcation is present, horseshoe structures of the jets in the planes are gradually produced and become ellipses, and the jet trajectories based on maximum velocity are similar to those based on maximum concentration.

Semi-empirical equations are presented to predict major near field characteristics. These provide guidance for designing multiport diffusers and assessing environmental impact.

Strategic management and management of innovation and technology.

The course can be used for undergraduate and postgraduate students. The case would be relevant in the strategic management course to understand the concept of technology strategy and the various evaluation parameters guiding firms in their technology decisions. A refresher of the concept of value chain analysis can also be done through the case. It can also be used to teach innovation and technology management to understand the innovation process and the importance of various organizational factors for taking technology decisions.

The case tries to bring together different aspects of technological innovation and technology strategy at North Delhi Power Ltd, Delhi which has taken various initiatives to turnaround the dilapidated power distribution industry in India. It details the various technological initiatives taken by the company to revamp the power distribution situation of the country. Discussion in the case also revolves around the technology decisions (technology strategy) taken by the company to drive the technological initiatives. The organizational culture supporting technology decisions and the technological initiatives are also woven into the case.

After a discussion on the case students will be in a better position to appreciate various decisions which firms take with respect to technology. They will get an understanding of what is technological innovation and about the technological innovation process. The importance of organizational factors to supplement technology decisions and innovation will be brought out in the case.

Teaching note.

This paper aims to present a novel numerical technique for solving the incompressible multiphase mixture model.

The multiphase mixture model contains a set of momentum and continuity equations for the mixture phase, a second phase continuity equation and the algebraic equation for the relative velocity. For solving continuity equation for the second phase and advection term of momentum, an improved approach fine grid advection-multiphase mixture flow (FGA-MMF) is developed. In the FGA-MMF method, the continuity equation for the second phase is solved with higher-order schemes in a two times finer grid. To solve the advection term of the momentum equation, the advection fluxes of the volume fraction in the continuity equation for the second phase are used.

This approach has been used in various tests to simulate unsteady flow problems. Comparison between numerical results and experimental data demonstrates a satisfactory performance. Numerical examples show that this approach increases the accuracy and stability of the solution and decreases non-monotonic results.

The solver for the multi-phase mixture model can only be adopted to solve the incompressible fluid flow.

The paper developed an innovative solution (FGA-MMF) to find multi-phase flow field value in the multi-phase mixture model. Advantages of the FGA-MMF technique are the ability to accurately determine the phases interpenetrating, decreasing the numerical diffusion of the interface and preventing instability and non-monotonicity in solution of large density variation problems.

WILL ROGERS, the great American humorist used to say, ‘All I know is what I read in the papers’. It would not be true to say that the daily press will tell us all that the Institute Meeting brings forth in science and technology, but news‐papermen have a flair for the significant. Accordingly, when the New York Times devoted a half‐column editorial to the luncheon speech of Admiral Luis de Florez, it was because this engineer, with so many war‐time training devices and methods to his credit, had once again evolved a valuable idea, a Synthetic Aircraft to serve in the development and testing of new aeroplanes. During the war the Navy developed and used Synthetic Aircraft for training men in gunnery, bombing, radio work, meteorology, the handling of rockets and torpedoes. Moreover, with the aid of complex electronic devices, computers, electric analysers, it was possible to subject young pilots, in almost uncanny fashion, to simulated emergency conditions, the cutting out of an engine, combat damage. The Navy spent S100,000,000 on its synthetic trainers and saved millions of hours of training time and billions of dollars. In pioneer days, to build a new plane cost a few thousand dollars and in the test flight only one man risked his life. Today the first flight hazards millions of dollars and the lives of several men. Admiral De Florez suggested that the building of synthetic aircraft to reproduce the flight characteristics of a new machine in operating form rather than to rely on calculations, however learned they might be. Let us quote his own words: