Effects of ramped wall temperature and concentration on viscoelastic Jeffrey’s fluid flows from a vertical permeable cone

In thermo-fluid dynamics, free convection flows external to different geometries such as cylinders, ellipses, spheres, curved walls, wavy plates, cones etc. play major role in various industrial and process engineering systems. The thermal buoyancy force associated with natural convection flows can exert a critical role in determining skin friction and heat transfer rates at the boundary. In thermal engineering, natural convection flows from cones has gained exceptional interest. A theoretical analysis is developed to investigate the nonlinear, steady-state, laminar, non-isothermal convection boundary layer flows of viscoelastic fluid from a vertical permeable cone with a power-law variation in both temperature and concentration. The Jeffery’s viscoelastic model simulates the non-Newtonian characteristics of polymers, which constitutes the novelty of the present work. The transformed conservation equations for linear momentum, energy and concentration are solved numerically under physically viable boundary conditions using the finite-differences Keller-Box scheme. The impact of Deborah number (De), ratio of relaxation to retardation time (λ), surface suction/injection parameter (fw), power-law exponent (n), buoyancy ratio parameter (N) and dimensionless tangential coordinate (Ѯ) on velocity, surface temperature, concentration, local skin friction, heat transfer rate and mass transfer rate in the boundary layer regime are presented graphically. It is observed that increasing values of De reduces velocity whereas the temperature and concentration are increased slightly. Increasing λ enhance velocity however reduces temperature and concentration slightly. The heat and mass transfer rate are found to decrease with increasing De and increase with increasing values of λ. The skin friction is found to decrease with a rise in De whereas it is elevated with increasing values of λ. Increasing values of fw and n, decelerates the flow and also cools the boundary layer i.e. reduces temperature and also concentration. The study is relevant to chemical engineering systems, solvent and polymeric processes

Numerical investigation of CuO nanoparticles effect on forced convective heat transfer inside a mini-channel: Comparison of different approaches

This paper proceeds numerical investigation on forced convective heat transfer of nanofluids in laminar flow inside a mini-channel with circular cross-section under constant heat flux boundary condition at walls. Nanofluid contains CuO nanoparticles with diameter of 50 nanometer in water base fluid. At the entrance of channel, profiles of uniform velocity & temperature prevail. In order to obtain fully developed profiles, geometry of problem considers as L/D = 100. Problem is solved by means of 4 different models, including Homogeneous and Dispersion models in both of constant and variable thermophysical properties through the finite-volume method. The temperature-dependent properties was used for the first time in nanofluids dispersion model. It was regarded in the presence of nanoparticles the heat transfer coefficient will be increased to some considerable extent and the heat transfer enhancement strongly depends on the volume concentration of nanoparticles and Peclet number. Also, comparison with experimental data and literatures' correlations is carried out which indicates the Dispersion model in both cases is more precise and Homogeneous model (single phase) underestimates the Nusselt number in constant thermo physical properties

Natural convection heat and mass transfer in MHD fluid flow past a moving vertical plate with variable surface temperature and concentration in a porous medium

A numerical investigation of two-dimensional steady laminar free convection flow with heat and mass transfer past a moving vertical plate in a porous medium subjected to a transverse magnetic field is carried out. The temperature and concentration level at the plate surface are assumed to follow a power-law type of distribution. The governing non-linear set of equations is solved numerically employing a fully implicit finite difference method. Results are presented to illustrate the influence of different parameters such as Grashof number (Gr), porosity parameter (Kp), magnetic field parameter (Mn) and exponents in the power law variation of the surface temperature and concentration, m and n. The dimensionless velocity, temperature and concentration profiles are analyzed and numerical data for the local Nusselt number and Sherwood number are presented. The study accentuates the significance of the relevant parameters