  Severe contradictions exist between experimental observations and
computational predictions regarding natural convective thermal transport in
nanosuspensions. The approach treating nanosuspensions as homogeneous fluids in
computations has been pin pointed as the major contributor to such
contradictions. To fill the void, inter particle and particle fluid
interactivities (slip mechanisms), in addition to effective thermophysical
properties, have been incorporated within the present formulation. Through
thorough scaling analysis, the dominant slip mechanisms have been identified. A
Multi Component Lattice Boltzmann Model (MCLBM) approach has been proposed,
wherein the suspension has been treated as a non homogeneous twin component
mixture with the governing slip mechanisms incorporated. The computations based
on the mathematical model can accurately predict and quantify natural
convection thermal transport in nanosuspensions. The role of slip mechanisms
such as Brownian diffusion, thermophoresis, drag, Saffman lift, Magnus effect,
particle rotation and gravitational effects have been pictured articulately. A
comprehensive study on the effects of Rayleigh number, particle size and
concentration reveals that the drag force experienced by the particles is
dominantly responsible for deterioration of natural convective thermal
transport. In essence, the dominance of Stokesian mechanics in such
thermofluidic systems is established in the present study. For the first time,
as revealed though thorough survey of existent literature, a numerical
formulation explains the contradictions observed, rectifies the approach,
predicts accurately and reveals the crucial mechanisms and physics of buoyancy
driven thermal transport in nanosuspensions.
