Basant Kumar Jha and Michael O. Oni
The purpose of this paper is to investigate the impact of time-periodic thermal boundary conditions on natural convection flow in a vertical micro-annulus.
Abstract
Purpose
The purpose of this paper is to investigate the impact of time-periodic thermal boundary conditions on natural convection flow in a vertical micro-annulus.
Design/methodology/approach
Analytical solution in terms of Bessel’s function and modified Bessel’s function of order 0 and 1 is obtained for velocity, temperature, Nusselt number, skin friction and mass flow rate.
Findings
It is established that the role of Knudsen number and fluid–wall interaction parameter is to decrease fluid temperature, velocity, Nusselt number and skin friction.
Research limitations/implications
No laboratory practical or experiment was conducted.
Practical implications
Cooling device in electronic panels, card and micro-chips is frequently cooled by natural convection.
Originality/value
In view of the amount of works done on natural convection in microchannel, it becomes interesting to investigate the effect that time-periodic heating has on natural convection flow in a vertical micro-annulus. The purpose of this paper is to examine the impact of time-periodic thermal boundary conditions on natural convection flow in a vertical micro-annulus.
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Basant Kumar Jha and Babatunde Aina
The purpose of this paper is to further extend the work of Weng and Chen (2009) by considering heat generation/absorption nature of fluid.
Abstract
Purpose
The purpose of this paper is to further extend the work of Weng and Chen (2009) by considering heat generation/absorption nature of fluid.
Design/methodology/approach
Exact solution of momentum equation is derived separately in terms of Bessel’s function of first and second kind for heat-generating fluid and modified Bessel’s function of first and second kind for heat absorbing fluid.
Findings
During the course of numerical computations, it is found that skin friction and rate of heat transfer at outer surface of inner cylinder and inner surface of outer cylinder increases with the increase in heat generation parameter while the reverse trend is found in the case of heat absorption parameter.
Originality/value
In view of the amount of works done on natural convection with internal heat generation/absorption, it becomes interesting to investigate the effect of this important activity on natural convection flow in a vertical annular micro-channel. The purpose of this paper is to further extend the work of Weng and Chen (2009) by considering heat generation/absorption nature of fluid.
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Basant Kumar Jha and Babatunde Aina
The purpose of this paper is to investigate fully developed mixed convection flow in the steady-periodic regime for a Newtonian fluid in a vertical microtube in the presence of…
Abstract
Purpose
The purpose of this paper is to investigate fully developed mixed convection flow in the steady-periodic regime for a Newtonian fluid in a vertical microtube in the presence of velocity slip and temperature jump, which has not been accounted for in the literature.
Design/methodology/approach
To achieve this objective, the governing equations for the problem are separated into steady and oscillatory components using separation of variable method; this gives a pair of independent boundary value problems. This is then solved along with its boundary conditions and constraint equations using the method of undetermined coefficient. The exact solutions of momentum and energy equations are obtained under the velocity slip and temperature jump conditions.
Findings
The significant result from the study is that increase in rarefaction parameter as well as fluid–wall interaction parameter decreases the oscillation amplitude of the dimensionless velocity. Furthermore, it was found that the product of dimensionless frequency and Prandtl number initiate a strong convection current inside the microtube.
Practical implications
Such type of study may be used on the determination of the thermal and tangential momentum accommodation coefficients and be applicable to the designs and fabrications of microheat exchanger. Moreover, it provides the possibility to get a bench mark for numerical solvers with reference to basic flow configuration.
Originality/value
These solutions generally deserve great attention, since the application of a magnetic field has been found to be effective tool in controlling the convection current. The current work is aimed as an extension of the previous analytical studies to prove some insight into a number of industrial applications, which use similar configurations.
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Basant Kumar Jha and Muhammad Nasir Sarki
The purpose of this paper is to conduct a theoretical study on steady fully developed non-linear natural convection and mass transfer flow past an infinite vertical moving porous…
Abstract
Purpose
The purpose of this paper is to conduct a theoretical study on steady fully developed non-linear natural convection and mass transfer flow past an infinite vertical moving porous plate with chemical reaction and thermal diffusion effect. Closed-form expressions for dimensionless velocity, concentration, Sherwood number and skin-friction are obtained by solving the present mathematical model.
Design/methodology/approach
The fully developed steady non-linear natural convection and mass transfer flow near a vertical moving porous plate with chemical reaction and thermal diffusion effect is investigated. The non-linear density variation and Soret effect were taken into consideration. The dimensionless velocity, temperature and concentration profiles were obtained in terms of exponential functions, and were used to compute the governing parameters, skin-friction and Sherwood number.
Findings
The effect of coefficient of the non-linear density variation with the temperature (NDT) and concentration (NDC) parameter, chemical reaction parameter, thermal diffusion parameter are discussed with the aid of line graphs and tables. The analysis of the result shows that the velocity as well as skin-friction having higher values in the case of non-linear variation of density with temperature and concentration in comparison to linear variation of density with temperature and concentration. It is observed that the velocity and skin-friction increase with an increase in the Soret parameter.
Originality/value
The aim of this paper is to extend the work of Muthucumaraswamy (2002) by incorporating the thermal diffusion (Soret) effect and non-linear density variation with temperature (NDT) and concentration (NDC), on which, to the best knowledge of the authors, no studies have been carried out.
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Basant Kumar Jha and Michael O. Oni
The purpose of this paper is to investigate electrokinetic and mixed convection (pressure gradient and buoyancy) effects on reverse flow formation at the channel walls.
Abstract
Purpose
The purpose of this paper is to investigate electrokinetic and mixed convection (pressure gradient and buoyancy) effects on reverse flow formation at the channel walls.
Design/methodology/approach
The electrical potential distribution was modelled using the Poisson–Boltzmann equation while the governing momentum and energy equations are modelled from the Navier–Stokes equations and solved exactly.
Findings
It is found that flow reversal at the walls is enhanced by electrokinetic parameter whereas increasing degree of asymmetric parameter up to symmetric heating eliminates reverse flow formation at the walls no matter the electric charge distribution.
Originality/value
The results of this paper indicate that degree of asymmetric heating, mixed convection parameter and electrokinetic parameter regulate fluid velocity, rate of heat transfer, skin friction and reverse flow formation at the walls.
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The purpose of this paper is to consider unsteady free convection flow of a dissipative fluid past an exponentially accelerated infinite vertical porous plate in the presence of…
Abstract
Purpose
The purpose of this paper is to consider unsteady free convection flow of a dissipative fluid past an exponentially accelerated infinite vertical porous plate in the presence of Newtonian heating and mass diffusion.
Design/methodology/approach
The problem is governed by coupled non-linear partial differential equations with appropriate boundary conditions. A Galerkin finite element numerical solution is developed to solve the resulting well-posed two-point boundary value problem. It is a powerful, stable technique which provides excellent convergence and versatility in accommodating coupled systems of ordinary and partial differential equations.
Findings
It is found that the skin friction coefficient increases with increases in either of the Eckert number, thermal Grashof number, mass Grashof number or time whereas it decreases with increases in either of the suction parameter, Schmidt number or the acceleration parameter for both air and water. The skin friction coefficient is also found to decrease with increases in the values of the Prandtl number. In addition, it is found that the rate of heat transfer increases with an increase in the suction parameter and decreases with an increase in the Eckert number for both air and water. Lastly, it is found that the rate of heat transfer increases with increasing values of the Prandtl number and decreases with increasing time for all values of the Prandtl number.
Research limitations/implications
The present study has considered only Newtonian fluids. Future studies will address non-Newtonian liquids.
Practical implications
A very useful source of information for researchers on the subject of free convective flow over the surface when the rate of heat transfer from the surface is proportional to the local surface temperature.
Originality/value
This paper is relatively original and illustrates the effects of viscous dissipation on free convective flow past an exponentially accelerated infinite vertical porous plate with Newtonian heating and mass diffusion.
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Chandrima Chakraborty and Dipyaman Pal
This chapter discusses a survey of literature on efficiency, productivity and other issues related to pharmaceutical industry in India and across the globe. Econometric…
Abstract
This chapter discusses a survey of literature on efficiency, productivity and other issues related to pharmaceutical industry in India and across the globe. Econometric theoretical literature on technical efficiency (TE) as well as econometric theoretical literature on total factor productivity growth (TFPG) are discussed in separate sections. Individual sections discuss studies on the performance of the pharmaceutical industries in the Indian context, studies on the performance of the pharmaceutical industries in the international context, studies on the efficiency of Indian pharmaceutical industry (IPI), studies on the TFPG of the IPI, other studies on IPI and also studies on the performance of the pharmaceutical industries in the international context (other than India). This chapter discusses the existing study highlighting the gaps and presents the connection of the present study with the existing literature in the conclusion section.
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Roger Schweizer, Katarina Lagerström and Johan Jakobsson
The article aims to explain how the drivers of subsidiary evolution influence a multinational company's (MNC) research and development (R&D) subsidiary's evolution over time.
Abstract
Purpose
The article aims to explain how the drivers of subsidiary evolution influence a multinational company's (MNC) research and development (R&D) subsidiary's evolution over time.
Design/methodology/approach
The article draws on insights from a longitudinal comparative case study of three Swedish MNCs' Indian R&D units.
Findings
The study shows that the evolution of R&D units is a triangular showdown among headquarter assignments, local market constraints, and opportunities, and that subsidiary choice is an important driver of both mandated extension and stagnation. We summarize our findings in various propositions that emphasize different drivers over time and that highlight the strong impact of a subsidiary's understanding of the corporate immune system on the evolution of that subsidiary's R&D mandate.
Research limitations/implications
Drawing on the common limitations of a case study approach, further research is needed to test the suggested propositions with larger samples, ideally with subsidiaries in other emerging and developed markets.
Practical implications
The study illustrates the risks involved for subsidiary managers when pushing an R&D mandate-related initiative too far and provoking the corporate immune system. For headquarters management, the study highlights the importance of understanding that the development of R&D competence and capability at a subsidiary cannot be guided solely by headquarter assignments and local market characteristics; rather, the subsidiary's initiatives also need to be considered.
Originality/value
The study contributes to the literature on R&D internationalization by showing how the drivers of subsidiary evolution influence a subsidiary's R&D mandates over time and that subsidiary choice is an important driver of both mandated extension and stagnation.
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The purpose of this study is to highlight the key challenges and opportunities that lie with some of the alternative avenues/tools to promote financial access to MSME in India.
Abstract
Purpose
The purpose of this study is to highlight the key challenges and opportunities that lie with some of the alternative avenues/tools to promote financial access to MSME in India.
Design/methodology/approach
Initially, the study discusses the scope of various alternative avenues/tools for MSME financing along with traditional bank SME credits, highlighting some of the factors that will boost the high performance and growth of MSME in future.
Findings
There is a dominance of domestic banks in the MSME financing over cross-border banks in India. The study finds several opportunities lie in the MSME financing for the banks and other alternative avenues/tools: friendly government policies and improving the legal system make the business environment suitable for MSME financing business. There are several obstacles like discrete presence of clients, high operating cost and low profitability, lack of proper risk management and low literacy rate that make MSME financing difficult for the SME finance business. Active government initiatives and other supporting factors will act as the game changer and promoter for the banks and other alternative avenues/tools for MSME financing.
Originality/value
The paper is original and brings out some valuable findings that will help the SME business clients to choose alternative access to finance.