V. Ramachandra Prasad

Modelling laminar transport phenomena in a Casson rheological fluid from a horizontal circular cylinder with partial slip

The laminar boundary layer flow and heat transfer of Casson non-Newtonian fluid from a permeable horizontal cylinder in the presence of thermal and hydrodynamic slip conditions is analysed. The cylinder surface is maintained at a constant temperature. The boundary layer conservation equations, which are parabolic in nature, are normalised into non-similar form and then solved numerically with the well-tested, efficient, implicit, stable Keller–Box finite-difference scheme. Increasing velocity slip induces acceleration in the flow near the cylinder surface and the reverse effect further from the surface. Increasing velocity slip consistently enhances temperatures throughout the boundary layer regime. An increase in thermal slip parameter strongly decelerates the flow and also reduces temperatures in the boundary layer regime. An increase in Casson rheological parameter acts to elevate considerably the skin friction (non-dimensional wall shear stress) and this effect is pronounced at higher values of tangential coordinate. Temperatures are however very slightly decreased with increasing values of Casson rheological parameter. Increasing mass flow injection (blowing) at the cylinder surface causes a strong acceleration, whereas increasing suction is found to induce the opposite effect. The study finds applications in rheological chocolate food processing.

Heat and Mass Transfer of Nanofluid from Horizontal Cylinder to Micropolar Fluid

Buoyancy-driven laminar free-convection flow, heat, and mass of a non-Newtonian nanofluid from a horizontal circular cylinder to a micropolar fluid have been investigated numerically using an implicit finite difference scheme. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. A nonsimilarity solution is presented that depends on the Prandtl number Pr, Schmidt number Sc, Brownian motion parameter Nb, thermophoresis parameter Nt, material parameter K, and buoyancy ratio parameter N. It is observed that increasing the Brownian motion parameter increases the temperature, Sherwood number, and wall couple stress but decreases the velocity, concentration, angular velocity, skin friction, and Nusselt number. An increase in the thermophoresis parameter is observed to accelerate the velocity, concentration, angular velocity, skin friction, and Nusselt number, whereas it decreases the temperature, the reduced Sherwood number, and wall couple stress. The velocity, angula...

Flow and Heat Transfer of Jeffreys Non-Newtonian Fluid from Horizontal Circular Cylinder

The boundary-layer flow and heat transfer of an incompressible Jeffreys viscoelastic fluid from a permeable horizontal circular cylinder is analyzed. The surface of the cylinder is maintained at a constant temperature. The boundary-layer conservation equations, which are parabolic in nature, are normalized into nonsimilar form and then solved numerically with the well-tested, efficient, implicit, stable Keller-box finite difference scheme. The variation of the reduced Nusselt number and local skin-friction coefficient with Deborah number and suction parameter, for various values of Prandtl number, and ratio of relaxation to retardation times are tabulated and provided in graphical form. It is found that the velocity is reduced with increasing Deborah number, whereas the temperature is increased. Increasing the ratio of relaxation to retardation times enhances the velocity but decreases the temperature. Increasing the Deborah number is observed to decrease the Nusselt number (heat transfer rate) and the sk...

Free Convection Flow and Heat Transfer of Non-Newtonian Tangent Hyperbolic Fluid from an Isothermal Sphere with Partial Slip

An analysis is presented for the nonlinear steady boundary layer flow and heat transfer of an incompressible Tangent Hyperbolic non-Newtonian fluid from an isothermal sphere in the presence of thermal and hydrodynamic slip condition. The transformed conservation equations are solved numerically subject to physically appropriate boundary conditions using a second-order accurate implicit finite difference Keller-box technique. The numerical code is validated with previous studies. The influence of a number of emerging non-dimensional parameters, namely the Weissenberg number (We), the power law index (n), Velocity slip (Sf), thermal jump (ST), Prandtl number (Pr) and dimensionless tangential coordinate (ξ) on velocity and temperature evolution in the boundary layer regime are examined in detail. Furthermore, the effects of these parameters on surface heat transfer rate and local skin friction are also investigated. Validation with earlier Newtonian studies is presented and excellent correlation achieved. It is observed that velocity, skin friction and the Nusselt number (heat transfer rate) are reduced with increasing (We), whereas the temperature is enhanced. Increasing power (n) enhances velocity and Nusselt number (heat transfer rate) but reduces temperature and skin friction. An increase in Sf, is observed to enhance velocity and Nusselt number but reduces temperature and local skin friction. Whereas increasing ST is found to decrease velocity, temperature, skin friction and Nusselt number. The study is relevant to chemical materials processing applications.

Mixed Convection Flow of Magnetic Viscoelastic Polymer from a Nonisothermal Wedge with Biot Number Effects

Magnetic polymers are finding increasing applications in diverse fields of chemical and mechanical engineering. In this paper, we investigate the nonlinear steady boundary layer flow and heat transfer of such fluids from a nonisothermal wedge. The incompressible Eyring-Powell non-Newtonian fluid model is employed and a magnetohydrodynamic body force is included in the simulation. The transformed conservation equations are solved numerically subject to physically appropriate boundary conditions using a second-order accurate implicit finite difference Keller Box technique. The numerical code is validated with previous studies. The influence of a number of emerging nondimensional parameters, namely, the Eyring-Powell rheological fluid parameter (), local non-Newtonian parameter based on length scale (), Prandtl number (Pr), Biot number (), pressure gradient parameter (), magnetic parameter (), mixed convection parameter (), and dimensionless tangential coordinate (), on velocity and temperature evolution in the boundary layer regime is examined in detail. Furthermore, the effects of these parameters on surface heat transfer rate and local skin friction are also investigated.

Numerical Study of Non-Newtonian Boundary Layer Flow of Jeffreys Fluid Past a Vertical Porous Plate in a Non-Darcy Porous Medium

Polymeric enrobing flows are important in industrial manufacturing technology and process systems. Such flows are non-Newtonian. Motivated by such applications, in this article we investigate the nonlinear steady state boundary layer flow, heat, and mass transfer of an incompressible Jefferys non-Newtonian fluid past a vertical porous plate in a non-Darcy porous medium. The transformed conservation equations are solved numerically subject to physically appropriate boundary conditions using a versatile, implicit, Keller-box finite-difference technique. The numerical code is validated with previous studies. The influence of a number of emerging non-dimensional parameters, namely Deborah number (De), Darcy number (Da), Prandtl number (Pr), ratio of relaxation to retardation times (λ), Schmidt number (Sc), Forchheimer parameter (Λ), and dimensionless tangential coordinate (ξ) on velocity, temperature, and concentration evolution in the boundary layer regime are examined in detail. Furthermore, the effects of these parameters on surface heat transfer rate, mass transfer rate, and local skin friction are also investigated. It is found that the boundary layer flow is decelerated with increasing De and Forchheimer parameter, whereas temperature and concentration are elevated. Increasing λ and Da enhances the velocity but reduces the temperature and concentration. The heat transfer rate and mass transfer rates are found to be depressed with increasing De and enhanced with increasing λ. Local skin friction is found to be decreased with a rise in De, whereas it is elevated with increasing λ. An increasing Sc decreases the velocity and concentration but increases temperature.

Unsteady Mixed Convective Flow in a Porous Lid-Driven Cavity with Constant Heat Flux

In this paper, we present the numerical analysis of mixed convection in a square cavity filled with porous medium. The left wall of the enclosure is kept at a constant heat flux, and the dimensionless governing equations are solved numerically with Marker and Cell (MAC) method. The numerical results are discussed graphically with the effect of Darcy number, Prandtl number, Rayleigh number, Grashof number, Reynolds number, temperature and streamlines.

MAC simulation of thermosolutal natural convection in a porous enclosure with opposing temperature and concentration gradients

A numerical study is conducted on thermosolutal natural convective flow inside a porous mixture of a rectangular enclosure with aspect ratio four. The flow enhancement is observed due to rising of Rayleigh number and Darcy number with buoyancy parameter. The transport equations for continuity, momentum, energy and species transfer are solved numerically with Marker and Cell (MAC) method. Two dimensional computational visualization results illustrating the influence of fluid parameters such as Darcy number, Rayleigh number and buoyancy ratio on contour maps of the Streamlines, Isotherms, and Iso-concentrations as well as the mid-section of velocity of the cavity are reported and discussed. The local Nusselt number and Sherwood numbers are increasing along the vertical walls for increasing Darcy number. Keywords— Porous medium, Isothermal walls, Double Diffusive Natural Convection, Aspect ratio, Rectangular Enclosure, MAC method.