Purpose

This paper aims to explore, through a numerical study, buoyant convective phenomena in a porous cavity containing a hybrid nanofluid, taking into account the local thermal nonequilibrium (LTNE) approach. The cavity contains a solid block in the shape of a cross (+). It will be helpful to develop and optimize the thermal systems with intricate geometries under LTNE conditions for a variety of applications.

Design/methodology/approach

To attain the objective, the system governing partial differential equations (PDEs), expressed as functions of the current function and temperature, and are solved numerically by the finite difference approach. The authors carefully examine the heat transfer rates and dynamics of the micropolar hybrid nanofluid by presenting fluid flow contours, isotherms of the liquid and solid phases, as well as contours of streamlines, isotherms and concentration of the fluid. Key parameters analyzed include heated length (B = 0.1–0.5), porosity (ε = 0.1–0.9), heat absorption/generation (Q = 0–8), length wave (λ = 1–3) and the interphase heat transfer coefficient (H* = 0.05–10). The equations specific to the flow of a micropolar fluid are converted into classical Navier–Stokes equations by increasing the porosity and pore size.

Findings

The results showed that the shape, strength and position of the fluid circulation are dictated by the size of the inner obstacle (B) as well as the effective length of the heating wall. The lower value of obstruction size, as well as heating wall length, leads to a higher rate of heat transfer. Heat transfer is much higher for the higher amount of heat absorption instead of heat generation (Q). The higher porosity values lead to lesser fluid resistance, which leads to a superior heat transfer from the hot source to the cold walls. The surface waviness of 4 leads to superior heat transfer related to any other waviness.

Research limitations/implications

This work can be further investigated by looking at thermal performance in the existence of various-shaped obstructions, curvature effects, orientations, boundary conditions and other variables. Numerical simulations or experimental studies in different multiphysical contexts can be used to achieve this.

Practical implications

Many technical fields, including heat exchanging unit, crystallization processes, microelectronic units, energy storage processes, mixing devices, food processing, air conditioning systems and many more, can benefit from the geometric configurations investigated in this study.

Originality/value

This work numerically explores the behavior of micropolar nanofluids (a mixture of copper, aluminum oxide and water) within a porous inclined enclosure with corrugated walls, containing a solid insert in the shape of a cross in the center, under the oriented magnetic field, by applying the nonlocal thermal equilibrium model. It analyzes in detail the heat transfer rates and dynamics of the micropolar nanoliquid by presenting the flow patterns, the temperature of liquid and solid phases, as well as the variations in the flow, thermal and concentration fields of the fluid.

中文翻译：

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辐射和产热对混合纳米流体填充斜波浪多孔腔中 MHD 自然对流的影响，包括十字形障碍物

 目的

本文旨在通过数值研究探索包含混合纳米流体的多孔腔中的浮力对流现象，同时考虑局部热非平衡 （LTNE） 方法。空腔包含一个十字形的实心块 （+）。在 LTNE 条件下为各种应用开发和优化具有复杂几何形状的热系统将有助于。

设计/方法/方法

为了实现这一目标，控制偏微分方程 （PDE） 的系统表示为电流函数和温度的函数，并通过有限差分方法进行数值求解。作者通过提供流体流动等值线、液相和固相的等温线以及流线等温线、等温线和流体浓度，仔细研究了微极杂化纳米流体的传热速率和动力学。分析的关键参数包括加热长度 （B = 0.1–0.5）、孔隙率 （ε = 0.1–0.9）、吸热/产生 （Q = 0–8）、长度波 （λ = 1–3） 和相间传热系数 （H* = 0.05–10）。通过增加孔隙率和孔径，将特定于微极流体流动的方程转换为经典的 Navier-Stokes 方程。

 发现

结果表明，流体循环的形状、强度和位置由内部障碍物的大小 （B） 以及加热壁的有效长度决定。障碍物大小的值以及加热壁长度的较低值会导致较高的传热速率。对于较高的热量吸收量而不是热量产生 （Q），传热要高得多。较高的孔隙率值导致较小的流体阻力，从而实现从热源到冷壁的出色热传递。表面波纹度为 4 导致与任何其他波纹度相关的出色传热。

研究局限性/影响

通过观察存在各种形状的障碍物、曲率效应、方向、边界条件和其他变量的热性能，可以进一步研究这项工作。可以使用不同多物理环境中的数值模拟或实验研究来实现这一目标。

 实际意义

许多技术领域，包括热交换装置、结晶过程、微电子装置、储能过程、混合设备、食品加工、空调系统等等，都可以从本研究中研究的几何配置中受益。

 原创性/价值

这项工作通过应用非局部热平衡模型，在定向磁场下，数值探索了微极纳米流体（铜、氧化铝和水的混合物）在波纹壁多孔倾斜外壳内的行为，该外壳的中心包含一个十字形的固体嵌件。它通过呈现流动模式、液相和固相的温度以及流体的流动场、热场和浓度场的变化，详细分析了微极纳米液体的传热速率和动力学。