Nanofluid flow and heat transfer due to a rotating disk

• The nanoparticles Al2O3 and TiO2 cause a growth in the boundary layer thickness.
• The highest and smallest values of shear stress occur, respectively, for Ag and Al2O3.
• More torque is required to maintain the steady rotation if nanofluids Ag, Cu and CuO are used.
• An increase in nanoparticles volume fraction enhances the thermal layer thickness.
• Cu has the greatest heat transfer rate and TiO2 has the lowest heat transfer rate.

The nanofluid boundary layer flow over a rotating disk is the main concern of the present paper. Unlike the traditional Von Karman problem in which a Newtonian regular fluid is assumed, water-based nanofluids containing nanoparticle volume fraction of Cu, Ag, CuO, Al2O3 and TiO2 are taken into account. The governing equations of motion are reduced to a set of nonlinear differential equations by means of the conventional similarity transformations which are later treated by a spectral Chebyshev collocation numerical integration scheme. The flow and temperature fields as well as the shear stress and heat transfer characteristics are computed for certain values of the nanoparticle volume fraction. A comparative analysis is made in terms of shear stress and cooling properties of considered nanofluids. A mathematical analysis is eventually provided to prove why the nanofluids are advantageous as far as the heat transfer enhancement is concerned. Although the physical features highly rely on the type of the considered nanoparticles, it is found that the heat transfer is greatly enhanced by addition of nanofluid Cu.