Abstract

In this work, the interaction impacts of solid nanoparticles and magnetic force on the entropy generation rates for three-dimensional forced convection over an inclined step in the presence of Brownian movement are examined. To achieve this goal, analysis of the thermodynamics second law is used. The working fluids in this three-dimensional problem are the ${\mathrm{Al}}_2{\mathrm{O}}_3–{\mathrm{H}}_2\mathrm{O}$ and $\mathrm{CuO}–{\mathrm{H}}_2\mathrm{O}$ nanofluids. To consider the impact of Brownian movement on the effective properties of these both nanofluids, the Koo–Kleinstreuer–Li (KKL) correlation is applied. Impacts of magnetic force $\left(Ha=0–100\right)$ and nanoparticles concentrations $\left(\varphi =0.0–0.06\right)$ on the entropy generation and the flow irreversibility are investigated in details. The predictions present that the ${\mathrm{Al}}_2{\mathrm{O}}_3–{\mathrm{H}}_2\mathrm{O}$ nanofluid is more suitable for the optimal design of the hydrothermal systems. Besides, the highest magnitudes of the total entropy generation number in downstream of step are noted for the case of $Ha=100$ and $\varphi =0.06.$

摘要

在这项工作中，研究了固体纳米粒子和磁力对在存在布朗运动的情况下在倾斜台阶上的三维强制对流熵产生率的相互作用的影响。为了实现这一目标，使用了热力学第二定律的分析。这个三维问题中的工作流体是${\mathrm{铝}}_2{\mathrm{哦}}_3——{\mathrm{H}}_2\mathrm{哦}$ 和 $\mathrm{氧化铜}——{\mathrm{H}}_2\mathrm{哦}$纳米流体。为了考虑布朗运动对这两种纳米流体的有效性质的影响，应用了Koo-Kleinstreuer-Li (KKL)相关性。磁力的影响$\left(H\mathrm{一个}=0——100\right)$ 和纳米粒子浓度 $\left(\phi =0.0——0.06\right)$详细研究了熵产生和流动不可逆性。预测显示，${\mathrm{铝}}_2{\mathrm{哦}}_3——{\mathrm{H}}_2\mathrm{哦}$纳米流体更适合于水热系统的优化设计。此外，对于步骤下游的总熵生成数的最高幅度被注意到$H\mathrm{一个}=100$ 和 $\phi =0.06.$