Purpose

This paper aims to present a numerical investigation into heat transfer and entropy generation resulting from magnetohydrodynamic laminar flow through a microchannel under asymmetric boundary conditions. Furthermore, the authors consider the effects of viscous dissipation and Joule heating.

Design/methodology/approach

The finite difference method is used to obtain the numerical solution. Simulations are conducted across a broad range of Hartmann (Ha = 0 ∼ 40) and Brinkman (Br = 0.01 ∼ 1) numbers, along with various asymmetric isothermal boundaries characterized by a heating ratio denoted as ϕ.

Findings

The findings indicate a significant increase in the Nusselt number with increasing Hartmann number, regardless of whether Br equals zero or not. In addition, it is demonstrated that temperature differences between the microchannel walls can lead to substantial distortions in fluid temperature distribution and heat transfer. The results reveal that the maximum entropy generation occurs at the highest values of Ha and η (a dimensionless parameter emerging from the formulation) obtained for ϕ = −1. Moreover, it is observed that local entropy generation rates are highest near the channel wall at the entrance region.

Originality/value

The study provides valuable insights into the complex interactions between magnetic fields, viscous dissipation and Joule heating in microchannel flows, particularly under asymmetric heating conditions. This contributes to a better understanding of heat transfer and entropy generation in advanced microfluidic systems, which is essential for optimizing their design and performance.

中文翻译：

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不对称加热下粘性焦耳加热 MHD 微通道流动的传热和熵产生

 目的

本文旨在对不对称边界条件下通过微通道的磁流体动力层流引起的传热和熵产生进行数值研究。此外，作者还考虑了粘性耗散和焦耳热的影响。

设计/方法论/途径

采用有限差分法获得数值解。模拟在广泛的 Hartmann ( Ha = 0 ∼ 40) 和 Brinkman ( Br = 0.01 ∼ 1) 数以及以加热比表示为phi的各种不对称等温边界上进行。

 发现

研究结果表明，无论Br是否为零，随着哈特曼数的增加，努塞尔数显着增加。此外，事实证明，微通道壁之间的温差会导致流体温度分布和传热的显着扭曲。结果表明，最大熵产生发生在当phi = -1 时获得的 Ha 和η （公式中出现的无量纲参数）的最高值。此外，据观察，局部熵产生率在入口区域的通道壁附近最高。

 原创性/价值

该研究为微通道流动中磁场、粘性耗散和焦耳热之间的复杂相互作用（特别是在不对称加热条件下）提供了有价值的见解。这有助于更好地理解先进微流体系统中的传热和熵产生，这对于优化其设计和性能至关重要。