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The flow of nanofluids in a corrugated channel has been shown to have a significant impact on heat transfer performance, and has therefore become an important area of research. The ob- jective of this paper is to understand the thermal behavior of Al2O3/water nanofluid in a sinu-soidal and square channel and to identify ways to optimize heat transfer performance in such configurations. For this purpose, a numerical simulation was conducted using ANSYS-Fluent software 16.0 on entropy generation and thermo-hydraulic performance of a wavy channel with the two corrugation profiles (sinusoidal and square). The analyses were carried out under laminar forced convection flow conditions with constant heat flux boundary conditions on the walls. The influence of various parameters, such as particle concentration (0–5%), particle di-ameter (10nm , 40nm and 60nm), and Reynolds number (200 < Re < 800) on the heat transfer, thermal, and frictional entropy generation, and Bejan number was analyzed. Moreover, the distribution of streamlines and static temperature contours has been presented and discussed, and a correlation equation for the average Nusselt number based on the numerical results is presented. One of the most significant results obtained is that the inclusion of nanoparticles (5% volume fraction) in the base fluid yielded remarkable results, including up to 41.92% and 7.03% increase in average Nusselt number for sinusoidal and square channels, respectively. The sinusoidal channel exhibited the highest thermo-hydraulic performance at Re= 800 and φ= 5%, approximately THP= 1.6. In addition, the increase of nanoparticle concentration from 0% to 5% at Re= 800 and dnp= 10nm, diminishes the total entropy generation by 28.39 % and 22.12 % for sinusoidal and square channels, respectively, but when the nanoparticle diameter decreases from 60nm to 10nm at ϕ= 5% and Re= 800, the total entropy generation in the sinusoidal channel decreases by 34.85%, whereas in the square channel, it decreases by 20.05%. Therefore, rather than using a square channel, it is preferable and beneficial to use small values of nanoparticle diameter and large values for each of ϕ and Re in the sinusoidal wavy channel. Overall, the study of nanofluid flow in a wavy channel can provide valuable insights into the behavior of nanofluids and their potential applications in a variety of fields, including manufacturing, energy produc-tion, mining, agriculture, and environmental engineering.

The effect of Polyethylene Oxide (PEO) with a molecular weight 10000g/mol on the rheological behavior of bentonite suspension was examined in terms of viscosity, yield stress and viscoelastic modulus (G’ and G’’); characteristic of complex behaviour of montmorillonite in water. A Physica MCR301 rheometer has been used to measure the rheological properties of samples (6% bentonite) as well as bentonite-PEO mixtures at different concentrations of PEO (0.18%, 0.25%, 0.5% and 1%). The polyethylene oxide adsorbs onto clay particles, which changes their basic characteristics depending on the amount of PEO adsorbed.

Abstract:In this paper, we characterized at first, the rheological behavior of the bentonite suspensions and the aqueous solutions of PEO (polyethylene oxide). Then we are going to investigate the influence of this polymer in a water-based drilling fluid model (6% of bentonite suspension). The objective is to exhibit how the non-ionic polymer with molecular weight 6x10 3 g/mol. of varying concentration mass (0.7%, 1%, 2% and 3%) significantly alter the rheological properties (yield stress, viscosity, loss and elastic modulus) of the bentonite suspensions. The rheological measurements made in simple shear and in dynamic on the mixture (water-bentonite-PEO), showed rheological properties of bentonite suspensions both in the presence and absence of non-ionic polymer. The PEO presents an affinity for the bentonite particles slowing down their kinetic aggregation. The analysis by XRD (X-rays diffraction) also allowed understanding the structure of this mixture. It had revealed the intercalation between of the clay platelets on one hand, and the links bridges assured by the chains of polymer between bentonite particles beyond a critical concentration in PEO on the other hand.