Boundary integral study of nanoparticle flow behaviour in the proximity of a solid wall

Compared with traditional heat transfer fluids, the greater thermal conductivity and better convective heat transfer behaviour with little pressure penalty have made nanofluids one of the most promising emerging technologies in the field of heat transfer applications. There is however only limited knowledge of the mechanisms by which these improvements are obtained and how other factors (particle clustering, migration, interactions with the walls, etc) influence the behaviour of the nanofluids. In this study, a boundary integral formulation is
used to simulate the flow of Al₂O₃/water with 1.05% volume concentration in the vicinity of a plane wall with special attention to particle behaviour and interactions. The simulation includes effects from Brownian motion, van der Waals attraction, electrostatic short range repulsion forces and buoyancy in order to assure physical representation. Viscous drag force and hydrodynamic interaction between the particles are calculated implicitly from the flow field improving the accuracy of the calculations. Results showed that a zone with ∼17% higher concentration (∼0.6% additional increase in thermal conductivity) as created ∼0.3µm away from the wall; this can help increase the heat conductivity and thus improve heat transfer. High cross flow velocities were also observed which can contribute to mixing in the boundary layer further improving the performance of the nanofluid.