MHD radiative Gr-Ag-TiO₂/H₂O ternary hybrid nanofluid flow upon a permeable movable wedge with irreversibility analysis

The mass-based ternary hybrid nanofluid model is applied for the magnetohydrodynamic (MHD) flow over a moving wedge with wall permeability, thermal radiation, and convective boundary condition. The masses of the nanoparticles and the base fluid are considered instead of the volumetric concentration of the first, the second, and the third nanoparticles. In the base fluid of water, three types of nanoparticles such as titania, silver, and graphene have been embedded. A similarity method is used to reduce variables and also to turn prominent equations of ternary hybrid nanofluid flow into a simplified form. The shooting technique with the Runge-Kutta-Felhberg method has been used to numerically solve the converted boundary layer equations. The largest Nusselt number is related to the ternary hybrid nanofluid, in which a heat transfer enhancement of 6.55% has been obtained in comparison with regular fluid. The Nusselt number for five shapes of the third nanoparticles is obtained (when both the first and second nanoparticles are spherical), and when the third nanoparticle has the shape of the disk, the most heat transfer has occurred. The highest entropy generation is related to the stagnation point case (<i>m</i> = 1) and the lowest belongs t the downhill case (<i>m</i> = –0.0825).本研究采用基于质量的三元杂化纳米流体（ternary hybrid nanofluid）模型，研究壁面渗透性、热辐射与对流边界条件下运动楔体表面的磁流体动力学（magnetohydrodynamic, MHD）流动。相较于以第一、第二、第三类纳米颗粒的体积浓度为参数，本模型选取纳米颗粒与基液的质量作为考量变量。本次研究以水作为基液，嵌入二氧化钛、银、石墨烯三类纳米颗粒。采用相似变换法（similarity method）对控制变量进行约化，将三元杂化纳米流体流动的核心控制方程转化为简化形式。结合龙格-库塔-费尔贝格方法（Runge-Kutta-Felhberg method）的打靶法（shooting technique），用于数值求解约化后的边界层控制方程。三元杂化纳米流体的努塞尔数（Nusselt number）最大，相较于常规流体，其传热提升幅度可达6.55%。在第一、第二类纳米颗粒均为球形的前提下，本研究给出了第三类纳米颗粒五种不同形貌下的努塞尔数结果；当第三类纳米颗粒为圆盘形时，传热效果最优。熵产（entropy generation）最高的工况对应驻点（stagnation point）情形（<i>m</i> = 1），而最低熵产则对应下坡工况（<i>m</i> = –0.0825）。