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Highlights • The Buongiorno’s nanofluid model is introduced for cavity nanofluid flow. • The buoyancy term is given more concisely. • Non-uniform heating types of practical importance overlooked in literature are presented. • A novel wavelet-homotopy technique is proposed. • Physical mechanisms on cavity flows with various types of heated and lid-driven walls are conducted. Abstract The laminar mixed convection flow in an inclined lid-driven cavity filled with a nanofluid is investigated in the presence of internal heat generation. The two sidewalls of the enclosure are sinusoidally heated while the top and bottom walls are insulted. The Buongiorno’s model that incorporates the effects of Brownian motion and thermophoresis is applied to describe the nanofluid behaviours. Parametrical studies are given on the regimes of the complex flow, temperature and concentration fields. The developed equations are nondimensionalized and then solved numerically by the newly developed wavelet-homotopy technique. Comparisons with previously studies in literature are presented and found to be in excellent agreement. The results of this work indicate that the Grashof number, the slipping parameters, the nanoparticles related parameters, the inclination, the boundary coefficients including amplitude ratios of temperature and concentration, as well as the phase deviation have significant effects on characteristics of the cavity flow. [ABSTRACT FROM AUTHOR]

In this paper, we focus on the two-dimensional pulsating nanofluid flow through a parallel-plate channel in the presence of a magnetic field. The pulsating flow is produced by an applied pressure gradient that fluctuates with a small amplitude. A kind of proper transformation is used so that the governing equations describing the momentum and thermal energy are reduced to a set of non-dimensional equations. The analytical expressions of the pulsating velocity, temperature, and Nusselt number of nanofluids are obtained by the perturbation technique. In the present study, the effects of the Cu-H2O and Al2O3-H2O nanofluids on the flow and heat transfer in pulsating flow are compared and analyzed. The results show that the convective heat transfer effect of Cu-H2O nanofluids is better than that of Al2O3-H2O nanofluids. Also, the effects of the Hartmann number and pulsation amplitude on the velocity, temperature, and Nusselt number are examined and discussed in detail. The present work indicates that increasing the Hartmann number and pulsation amplitude can enhance the heat transfer of the pulsating flow. In addition, selecting an optimal pulsation frequency can maximize the convective heat transfer of the pulsating flow. Therefore, improved understanding of these fundamental mechanisms is conducive to the optimal design of thermal systems. [ABSTRACT FROM AUTHOR]

An investigation is made for a three-dimensional unsteady mixed nano-bioconvection flow between two contracting or expanding rotating discs. The passively controlled nanofluid model in which Brownian diffusion and thermophoresis are considered as the two dominant factors for nanoparticle/base-fluid slip mechanisms is introduced for description of this flow problem. A novel similarity transformation is introduced so that the governing equations embodying the conservation of total mass, momentum, thermal energy, nanoparticle volume fraction, and microorganisms are reduced to a set of five fully coupled ordinary differential equations. Exact solutions are then obtained analytically for this complex nonlinear system. Besides, the influences of various physical parameters on distributions of velocity, temperature, nanoparticle volume fraction, and the density of motile microorganisms, along with the local Nusselt number and the local wall motile microorganisms flux, are presented and discussed. It is expected that this study can provide a theoretical base for understanding the transport mechanisms of unsteady bioconvection in nanofluids. [ABSTRACT FROM AUTHOR]