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The present work investigates the Magneto-Marangoni convective flow of dusty second-grade nanofluid flow over a porous sheet in the presence of stagnation-point. The effects of chemical reaction, gyrotactic microorganisms are taken into account along with variable mass diffusivity, thermal radiation, and non-uniform heat source. The thermal reflection of nanoparticle molybdenum disulfide (Mo S 2 ) when it interacts with kerosene oil (KO) base fluid is determined. Nanoparticles and dust particles are presumptively spherical. The arising system of nonlinear PDEs is transformed into nonlinear ODEs by applying similarity transformations. Conservation of momentum, mass, concentration, energy, and density of microorganisms are used in to model the flow equations. The numeric expressions are computed by using the RKF-45th based shooting scheme. The outcomes revealed that the microorganisms, concentration, and temperature profiles decay in both phases, but velocity profiles of dust and fluid phases rise as the Marangoni ratio parameter grows. [ABSTRACT FROM AUTHOR]

Thermocapillary convection of moderate Prandtl number nanofluid in rectangular cavity is numerically investigated in this paper, and the effect of nanoparticle volume fraction on flow instability is analyzed. The computational results show that, the critical temperature difference deceases gradually with nanoparticle volume fraction increasing, and nanofluid thermocapillary convection is less stable than the base fluid. With the increase of nanoparticle volume fraction the velocity oscillatory amplitude decreases, but the oscillatory period increases. Nanofluid oscillatory thermocapillary convection has one dominant oscillation frequency, and with nanoparticles volume fraction increasing the second fundamental frequency strengthens gradually. [ABSTRACT FROM AUTHOR]

In order to reveal the influence of nanoparticle shape on heat transfer in nanofluid nucleate boiling process, a three-dimensional numerical investigation of nanofluid thermocapillary convection around a gas bubble is conducted. Five different shaped nanoparticles are used in this study and the nanofluid flow is simulated by two-phase mixture model. The thermocapillary convection intensity of nanofluid with spherical nanoparticles is the largest, which is followed by blade, brick, cylinder and platelet shapes, respectively. Non-spherical nanoparticles with a suitable shape and relatively high volume fraction are beneficial for heat transfer enhancement, and nanofluid containing blade shaped nanoparticles has the largest heat transfer enhancement, which is followed by platelet, cylinder and blade shapes respectively. In particular, as αp = 0.05 the average Nusselt number of nanofluid with blade, platelet, cylinder and blade shaped nanoparticles are increased by 22.8%, 11.7%, 7.7% and 2.8% relative to that of with spherical nanoparticle respectively. Moreover, the total entropy generation increases with nanoparticle sphericity increasing. [ABSTRACT FROM AUTHOR]

The present study aims to investigate Marangoni‐forced convective nanofluid flow over an electromagnetic actuator (Riga plate). A first‐order homogeneous chemical reaction is considered. The thermocapillary and solutocapillary Marangoni effect developed by the surface tension is considered as a driving force for the nanofluid. In addition, Grinberg‐term is accounted to involve the impact of Lorentz force impinged by the actuator in the model. A set of nonlinear ordinary differential equations is obtained via suitable transformations for a nonsimilar analysis. Series solutions are achieved through homotopy to discuss the behavior of the velocity field, thermal distribution, and concentration of the nanoparticles graphically. The variation in Nusselt and Sherwood numbers is discussed. The outcomes declared that the flow parallel to the surface of the plate is assisted by the Lorentz forces generated by electromagnetic bars of the actuator resulting in an enhancement in the fluid motion. Furthermore, the stronger Marangoni effect resulted in the declining trend of the temperature profile. The concentration of nanoparticles near the surface reduced intensive chemical reaction inside the nanofluid. [ABSTRACT FROM AUTHOR]

Buoyant-thermocapillary convection is an important heat transfer mechanism in nucleate boiling and nanofluids has been used as heat transfer medium extensively, so it is necessary to study the heat enhancement mechanism of nanofluids buoyant-thermocapillary convection around gas bubble. The present paper first reports the flow, heat transfer and entropy generation characteristics of nanofluids buoyant-thermocapillary convection around a gas bubble in a cavity, and the effects of nanoparticles volume fraction and size on buoyant-thermocapillary convection are discussed. The results show that, as nanoparticles volume fraction increases from 0 to 0.05, the convective intensity and entropy generation of buoyant-thermocapillary convection decreases gradually, and the average Nusselt number of bottom wall first increases and then decreases. As nanoparticles volume fraction is 0.02 the average Nusselt number is the largest and increased by 3.1% relative to that of pure fluid. As nanoparticles diameter increases from 20 nm to 80 nm, the temperature and flow fields indicate as the same structure, but the entropy generation increases gradually. The average Nusselt number of bottom wall increases slightly with nanoparticles diameter increasing, particularly, the average Nusselt number for nanoparticles diameter (dp) 80 nm is increased by 2.28% relative to that of dp = 20 nm. [ABSTRACT FROM AUTHOR]