Thermophoresis and Brownian motion effects on boundary layer flow of nanofluid in presence of thermal stratification due to solar energy

Abstract

The problem of laminar fluid flow, which results from the stretching of a vertical surface with variable stream conditions in a nanofluid due to solar energy, is investigated numerically. The model used for the nanofluid incorporates the effects of the Brownian motion and thermophoresis in the presence of thermal stratification. The symmetry groups admitted by the corresponding boundary value problem are obtained by using a special form of Lie group transformations, namely, the scaling group of transformations. An exact solution is obtained for the translation symmetrys, and the numerical solutions are obtained for the scaling symmetry. This solution depends on the Lewis number, the Brownian motion parameter, the thermal stratification parameter, and the thermophoretic parameter. The conclusion is drawn that the flow field, the temperature, and the nanoparticle volume fraction profiles are significantly influenced by these parameters. Nanofluids have been shown to increase the thermal conductivity and convective heat transfer performance of base liquids. Nanoparticles in the base fluids also offer the potential in improving the radiative properties of the liquids, leading to an increase in the efficiency of direct absorption solar collectors.

Peristaltic Motion of Nanofluid in a Curved Channel

“…Researchers concluded that heat transfer and solar collection processes can be improved through the addition of nanoparticles in the base fluids. Power tower solar collectors can benefit from the potential efficiency improvements that arise from a nanoparticle working fluid [14]. Nanofluid is a liquid suspended with nanometer-sized particles (diameter less than 50 nm) called nanoparticles.…”

Brownian movement and thermophoresis of nanoparticles in liquids

“…The movement of the particles was simulated for a period of 1,000,000s p using Eqs. (20) and (21). Since the starting position of the particles is at z = 0, the thermophoretic velocity of each particle was determined by dividing the final position of each particle in the z direction by the time of the simulation (1,000,000s p ).…”

“…It is also apparent that there is a misconception that the Brownian movement and thermophoresis are independent phenomena. This has led to the erroneous practice of accounting for both the Brownian movement and the thermophoretic velocity in simulations [21][22][23] . The result is the ''double-counting'' of the thermophoretic effect.…”

“…Engine oil Ethyl glycol R-134a velocity and most commercial software do not overrule this practice [21][22][23]. Another phenomenon that is occasionally connected with thermophoresis is the diffusiophoresis of particles.…”

Direct numerical simulation of the passive heat transfer in a turbulent flow with particle

“…Even though we now have a better understanding of turbulence modification by small solid particles, the mechanisms are complex and not easy to predict [7].…”