Ti t l e Ex p e ri m e n t al s t u dy of i m p r ov e d r h e olo gy a n d lu b ri city of d rillin g flui d s e n h a n c e d wi t h n a n o-p a r ticl e s

Nonlinear, steady‐state, viscous flow, and heat transfer between two stretchable rotating disks spinning at dissimilar velocities are studied with a non‐Fourier heat flux model. A nondeformable porous medium is intercalated between the disks and the Darcy model is used to simulate matrix impedance. The conservation equations are formulated in a cylindrical coordinate system and via the von Karman transformations are rendered into a system of coupled, nonlinear ordinary differential equations. The emerging boundary value problem is controlled by number of dimensionless parameters, that is, Prandtl number, upper disk stretching, lower disk stretching, permeability, non‐Fourier thermal relaxation, and relative rotation rate parameters. A perturbation solution is developed and the impact of selected parameters on radial and tangential velocity components, temperature, pressure, lower disk radial, and tangential skin friction components and surface heat transfer rate are visualized graphically. Validation of solutions with the homotopy analysis method is included. Extensive interpretation of the results is presented which are relevant to rotating disk bioreactors in chemical engineering.

Magnetic polymer materials processing involves many multi-physical and chemical effects. Motivated by such applications, in the present work a theoretical analysis is conducted of combined heat and mass transfer in unsteady mixed convection flow of micropolar fluid over an oscillatory inclined porous plate in a homogenous porous medium with heat source, radiation absorption and Joule dissipation. A first order homogenous chemical reaction model is used. The transformed non-dimensional boundary value problem is solved using a perturbation method and Runge-Kutta fourth order numerical quadrature (shooting technique). The emerging parameters dictating the transport phenomena are shown to be the gyro-viscosity micropolar material parameter, magnetic field parameter, permeability of the porous medium, Prandtl number, Schmidt number, thermal Grashof number, species Grashof number, thermal radiation-conduction parameter, heat absorption parameter, radiation absorption parameter, Eckert number, chemical reaction parameter and Eringen coupling number (vortex viscosity ratio parameter). The impact of these parameters on linear velocity, microrotation (angular velocity), temperature and concentration are evaluated in detail. Results for skin friction coefficient, couple stress coefficient, Nusselt number and Sherwood number are also included. Couple stress is observed to be reduced with stronger magnetic field. Verification of solutions is achieved with earlier published analytical results.

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The objective of this study is to develop a mathematical model for chemically reacting magnetic nanofluid flow with thermophoretic diffusion, Brownian motion and Ohmic magnetic heating in a Darcian permeable regime.The current flow model also considers a number of different nanofluid types i.e. Cu, Ag and Au nanoparticles with base fluid ethylene glycol. Effectively a nanoscale formulation combining the Buongiorno two-component model with the Tiwari-Das model is deployed so that a nanoparticle species diffusion equation is also included as well as material properties for specific nanoparticles and base fluids. By means of similarity transformations, non-linear dimensionless ordinary differential equations are derived (from the original partial differential equations) and solved numerically by means of Runge-Kutta-Fehlberg-fourth fifth order method. The effect of emerging parameters on velocity, temperature, concentration, skin friction, Nusselt number and Sherwood number profiles is visualized graphically. Validation with earlier studies is included. The computations show that temperatures are suppressed with greater thermal Grashof and Biot numbers. Nanoparticle-concentrations are strongly diminished with increasing reactive species and Lewis number, whereas Sherwood number is elevated with stronger chemical reaction effect. The study is relevant to magnetic nanomaterials processing.