Research on nanofluids has increased significantly in the last decade due to the distinctive potential in many applications such as enhanced heat transfer processes, drug delivery systems, and membrane manufacturing processes. The study of dispersion behavior of nanoparticles in liquids is a topic of keen interest towards the preparation of stable nanofluids. A comprehensive review on the recent progress in preparation and stability of nanofluids is presented. Settling of nanoparticles is the only predicament towards preparation of stable nanofluids which takes place due to formation of agglomerates. The settling behavior of nanoparticles in nanofluids and techniques to stop agglomeration are described. Nanofluid preparation techniques, assessment method of stability, and methods to reduce agglomeration are discussed.

No abstract

No abstract

No abstract

No abstract

The unsteady free convection flow of an electrically conducting fluid past an accelerated infinite vertical plate with constant heat flux is investigated under the influence of uniform transverse magnetic field fixed relative to the fluid or to the plate in the presence of heat generation or absorption. Two important cases, (i) exponentially accelerated plate (EAP) and (ii) uniformly accelerated plate (UAP), have been considered. The governing partial differential equations have been solved analytically using the Laplace transform technique and closed form solutions are obtained for the velocity and temperature fields without any restriction. The effects of system parameters such as the Prandtl number, heat generation or absorption, Grashof number, and magnetic field parameter on the flow fields are analyzed through graphs and tables. Further, the solution of the problem involves inverse Laplace transforms of some new exponential forms and these formulas are provided.

No abstract

The effects of thermal radiation and mass transfer on unsteady natural convection flow of an optically dense viscous incompressible fluid near a vertical plate with Newtonian heating have been investigated. Both physically important boundary conditions of uniform wall concentration (UWC) and uniform mass flux (UMF) are considered. Rosseland diffusion approximation is used to describe the radiative heat flux in the energy equation. The governing dimensionless boundary layer equations are solved analytically using the Laplace transform technique. The effects of mass to thermal buoyancy ratio parameter (N), Prandtl number (Pr), Schmidt number (Sc), and the radiation parameter (R) as well as time (t) on the velocity field and skin friction are determined. It is found that velocity increases for aiding flows and it decreases for opposing flows in the cases of both UWC and UMF. The skin friction is reduced with increasing species concentration in the presence of aiding flows for both UWC and UMF. Also, the velocity is greater in the case of UWC than the case of UMF at an early time, whereas the velocity is slightly greater in the case of UMF than that of UWC at a later time in the vicinity of the plate.