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The year 1980, the decade of the 80s, twenty years until the year 2000. The next ten years may be among the most critical faced by American business, and physical distribution managers in particular, in our history. Further, the developments in physical distribution practice and management, and especially the way in which some of the critical problems are solved, will have impacts on the health and progress of business into the year 2000 and beyond. The following paragraphs address some of the critical problems and issues faced by physical distribution managers. Where possible recent trends which affect these concerns are identified and the potential development of these trends through the 1980s is traced.

Self‐service food stores are a new emerging form of retail technology in Saudi Arabia. By focusing on relevant institutional, planning and operational dimensions, this exploratory study describes and analyses the process by which this form of food retailing was adopted. Data were collected from 96 stores located in three metropolitan areas of the Kingdom, and the results suggest that the sudden proliferation of these stores during the past decade was characterised by the lack of rational planning, short‐term decision making orientation, and limited concern for promotional activities. The analysis of the 62 study variables indicated that differences in store size exerted limited influence on store marketing activities and had a moderate effect on store planning and institutional dimensions.

This paper aims to address the problem of double-diffusive magnetohydrodynamics (MHD) non-Darcy convective flow of heat and mass transfer over a stretching sheet embedded in a thermally-stratified porous medium. The controlling parameters such as chemical reaction parameter, permeability parameter, etc., are extensively discussed and illustrated in this paper.

With the help of appropriate similarity variables, the governing partial differential equations are converted into ordinary differential equations. The transformed equations are solved using the spectral homotopy analysis method (SHAM). SHAM is a numerical method, which uses Chebyshev pseudospectral and homotopy analysis method in solving science and engineering problems.

The effects of all controlling parameters are presented using graphical representations. The results revealed that the applied magnetic field in the transverse direction to the flow gives rise to a resistive force called Lorentz. This force tends to reduce the flow of an electrically conducting fluid in the problem of heat and mass transfer. As a result, the fluid velocity reduces in the boundary layer. Also, the suction increases the velocity, temperature, and concentration of the fluid, respectively. The present results can be used in complex problems dealing with double-diffusive MHD non-Darcy convective flow of heat and mass transfer.

The uniqueness of this paper is the examination of double-diffusive MHD non-Darcy convective flow of heat and mass transfer. It is considered over a stretching sheet embedded in a thermally-stratified porous medium. To the best of the knowledge, a problem of this type has not been considered in the past. A novel method called SHAM is used to solve this modelled problem. The novelty of this method is its accuracy and fastness in computation.

The purpose of this study is to numerically investigate the confined single-walled carbon nanotube-water nanofluid jet impingement heating of a cooled surface with a uniform heat flux in the presence of a porous layer. The analysis of the convective heat transfer mechanism is introduced considering the buoyancy force effect under local thermal non-equilibrium conditions.

The governing equations for the nanofluid and solid phase are discretized by the finite volume method and the SIMPLE algorithm is used to solve these equations.

It is observed that there is an increase in a local variation of temperature along the upper wall with increasing Reynolds, Darcy and Grashof numbers. For given parameters, the optimum values of thermal conductivity ratio and porous layer thickness leading to better heating on the upper wall are found as K_r = 1.0 and S = 0.5, respectively. The maximum and minimum values of temperature on the upper wall are obtained in the case of higher nanoparticle volume fraction at Re = 100, however, the temperature values get higher along the upper wall with increasing nanoparticle volume fraction at Re = 300.

The effects of various parameters, such as Reynolds number, Darcy number and Grashof number, on thermal behavior and nanofluid flow are examined to determine the desirable heating conditions for the upper wall. This paper provides a solution to problems such as icing on the surface with a suitable thermal design and optimum geometric configuration.

The fully developed laminar mixed convection flow in inclined tubes subject to axially and circumferentially uniform heat flux has been studied numerically for a Boussinesq fluid. Dual solutions characterized by a two‐ and a four‐vortex secondary flow structure in a cross‐section normal to the tube’s longitudinal axis have been found for different combinations of the Grashof number Gr and of the tube inclination α for all Prandtl numbers between 0.7 and 7. In the two‐parameter space defined by Gr and α dual solutions occur: at a given α, if the Grashof number exceeds a critical value Gr_ℓ (for horizontal tubes Gr_ℓ is approximately 5.5 × 10⁵, 1.7 × 10⁵ and 1.7 × 10⁴ respectively for Pr = 0.7, 7 and 70); at a given Gr, if the tube inclination is below a critical value α_c (for Gr = 10⁶ this critical angle is approximately 62.5° and 83.5° respectively for Pr = 0.7 and 7). Numerical experiments carried out for developing flows indicate that the two‐vortex solution is the only stable flow structure.

The purpose of this paper is to compare the numerical laminar two‐dimensional unsteady natural convection in a partial sector‐shaped enclosure submitted respectively to a constant heat flux density q1 and a uniform temperature T1 on the inner cylindrical wall. The numerical model performed in this paper is applied more particularly for high Grashof numbers, in order to point out the advent and the development of pre‐turbulent flows. Results of numerical runs are presented. The mean Nusselt number on active walls is represented as a function of the Grashof number Gr and the aspect ratio F_r. The results may be correlated very well with an expression of the form \overlineNu = k1 Gr₁^k2, for technical calculations.

This study aims to deal with entropy generation and thermal analysis of magnetic hybrid nanofluid containing silver and gold as nanoparticles (Au-Ag/NPs) in the Eyring–Powell fluid.

The blood is used as a base fluid to study the rheological effects in a wavy asymmetric channel. The effect of viscous dissipation is also taken into account. The mathematical model is developed using the lubrication technique. The perturbation method is used to solve the nondimensional nonlinear differential equations, whereas the pumping properties have been analyzed using numerical integration.

The impact of entropy generation, Brinkman number, Hartmann number, nanoparticles volume fraction, thermal Grashof number, Brinkman number and Eyring–Powell fluid parameter is examined on the velocity profile, temperature profile and pumping characteristics. It is observed that the introduction of gold and silver nanoparticles boosts the velocity field in a smaller segment of the channel. The temperature profile rises for the increasing values of Hartmann number, Brinkman number and nanoparticle volume fractions while the temperature profile is restrained by the Eyring–Powell fluid parameter. The pumping rate rises in all sections as the thermal Grashof number and Hartmann number increase; however, the Eyring–Powell fluid parameter has the reverse effect. The volume of the trapping boluses is significantly affected by the Eyring–Powell fluid parameter, thermal Grashof number and fluid parameter.

The results are original and contribute to discover the role of hybrid nanoparticles under the influence of entropy generation viscous dissipation and magnetic fields. Pharmaceutical technology may use this research for things like better mucoadhesive drug delivery systems and more productive peristaltic micropumps.

The purpose of this research is to investigate the behavior of continuous hydromagnetic convective fluid within a porous medium. In this study, all fluid properties are assumed to remain constant, except for viscosity, which varies inversely with temperature. Additionally, the fluid experiences Newtonian heating, and the effects of the Dufour and Soret phenomena are considered. The study also examines how controlling constants affect the velocity, temperature and concentration profiles.

The model equations are transformed to ordinary differential equations adopting similarity transformations. The resulting coupled nonlinear differential equations are then solved numerically using the shooting method combined with the fourth order Runge-Kutta (RK-4) technique. The effects of varying parameters on the flow are presented through graphs and tables.

The consequences of supervising constants on the flow are encapsulated in charts. The findings are that the Biot number is crucial in determining the temperature distribution within a solid during transient heat transfer; a reduction in the velocity chart is experienced as the size of suction grows; the temperature distribution over the upright heated plate escalates dramatically as Dufour(Du) shot up; and a rise in fluid velocity as the Soret parameter increases. The current results are annotated in sketches for better understanding. Findings are authenticated in contrast with published works. Finally, viscosity dependent on temperature and Newtonian heating are crucial in determining the flow characteristics, heat transfer efficiency, pressure drop, flow stability and overall performance of fluid systems. Understanding and accounting for these variations are essential for the optimal design and operation of engineering applications involving fluids.

The peculiarity of the research is perusal of exploration of viscosity dependent on temperature and Newtonian heating above steady hydromagnetic convective flow in a percolating environment: Soret, Dufour consequences. To the best of authors’ understanding, problem like this has not been considered. The findings in this work will give a useful information to scientists and engineers.

This study aims to investigate thermo-bioconvection of oxytactic microorganisms occurring in a nanofluid-saturated porous lid-driven cavity in the presence of the magnetic field. The heating is provided through a bell-shaped curved bottom wall heated isothermally. The effects of the peak height of the curved bottom wall, bioconvection Rayleigh number (Rb), Darcy number (Da), Hartmann number (Ha), Peclet number (Pe), Lewis number (Le) and Grashof number (Gr) on the flow structure, temperature and the iso-concentrations of oxygen and microorganisms are examined and explained systematically. The local and global, characteristics of heat transfer and oxygen concentration, are estimated through the Nusselt number (Nu) and Sherwood number (Sh), respectively.

The governing equations of continuity, momentum, energy and additionally consisting of species transport equations for oxygen concentration and population density of microorganisms, are discretized by the finite volume method. The evolved linearized algebraic equations are solved iteratively through the alternate direction implicit scheme and the tri-diagonal matrix algorithm. The computation domain has meshed in non-uniform staggered grids. The entire computations are carried out through an in-house developed code written in FORTRAN following the SIMPLE algorithm. The third-order upwind and second-order central difference schemes are used for handling the advection and diffusion terms, respectively. The convergence criterion for the iterative process of achieving the final solution is set as 10–8 and 10–10, respectively, for the maximum residuals and the mass defect.

The results show that the flow and temperature distribution along with the iso-concentrations of oxygen and microorganisms are markedly affected by the curvature of the bottom wall. A secondary circulation is developed in the cavity that changes the flow physics significantly. The Nu increases with the peak height of the curved bottom wall and Da; however, it decreases with Ha and Rb. The Sh increases with Da but decreases with Ha and the peak height of the curved wall.

A similar study of bioconvection could be extended further considering thermal radiation, chemical attraction, gravity, light, etc.

The outcomes of this investigation could be used in diverse fields of multi-physical applications such as in food industries, chemical processing equipment, fuel cell technology and enhanced oil recovery.

The insights of bioconvection of oxytactic microorganisms using a curved bottom surface along with other physical issues such as nanofluid, porous substance and magnetic field are addressed systematically and thoroughly.

The purpose of this paper is to analyze the thermal-diffusion and diffusion-thermo effects on magnetohydrodynamics (MHD) natural convective flow through porous medium in a rotating system with ramped temperature.

Using the non-dimensional variables, the flow governing equations along with corresponding initial and boundary conditions have been transformed into non-dimensional form. These non-dimensional partial differential equations are solved by using finite element method. This method is powerful and stable. It provides excellent convergence and flexibility in providing solutions.

The effects of Soret number, Dufour number, rotation parameter, magnetic parameter, Hall current parameter, permeability parameter, thermal Grashof number, solutal Grashof number, Prandtl number, thermal radiation parameter, heat absorption parameter, Schmidt number, chemical reaction parameter and time on the fluid velocities, temperature and concentration are represented graphically in a significant way and the influence of pertinent flow governing parameters on the skin frictions and Nusselt number are presented in tabular form. On the other hand, a comparison for validation of the numerical code with previously published work is performed, and an excellent agreement is observed for the limited case existing literature.

A very useful source of information for researchers on the subject of MHD flow through porous medium in a rotating system with ramped temperature.

The problem is moderately original, as it contains many effects like thermal-diffusion (Soret) and diffusion-thermo (Dufour) effects and chemical reaction.