Purpose

The purpose of this paper is to analyze the heat and momentum transfer for steady two-dimensional incompressible nanofluid flow through a wavy channel with linearly varying amplitude in the entrance region.

Design/methodology/approach

The mass, momentum and energy conservation equations for laminar flow of Cu-water nanofluids are computationally solved using the finite element method. A parametric study is carried out by varying the dimensionless length of the channel section with varying amplitude (EL), Reynolds number (Re) and nanoparticle volume fraction (Φ) in the ranges 0 ≤ EL ≤ 25.5, 105 ≤ Re ≤ 900 and 0 ≤ Φ ≤ 0.04.

Findings

A higher heat transfer rate is seen in the wavy channel compared to a plane channel beyond a critical value of Re (Re_crit) whose value varies with EL; moreover, the overall heat transfer decreases with EL. The heat transfer rate increases with phi for all EL values investigated. The combined effects of the increase in the overall heat transfer and the associated pressure drop in the wavy channel compared to the parallel plate channel are presented as performance factor (PF) against EL. For the highest value of EL (= 25.5), PF monotonically decreases with Re. For smaller values of EL (= 5.5 and 11.5) and also for EL = 0, PF decreases with Re in the lower and the higher Re regimes, while it increases in the intermediate Re regime. In all cases, PF is higher for φ = 0.04 than for the base fluid. The sensitivity of the average Nusselt number to nanoparticle volume fraction follows a non-monotonic trend with the change in Re, φ and EL.

Practical implications

This study finds relevance in several applications such as solar collectors, heat exchangers and heat sinks.

Originality/value

To the best of the authors’ knowledge, the analysis of forced convection flow of nanofluid through a wavy channel with linearly varying amplitude is reported for the first time in the literature.

中文翻译：

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强制对流纳米流体流过入口处线性变化波浪通道的分析

目的

本文的目的是分析稳定的二维不可压缩纳米流体流过入口区域具有线性变化振幅的波浪通道的热量和动量传递。

设计/方法/途径

Cu-水纳米流体层流的质量、动量和能量守恒方程是使用有限元方法计算求解的。通过在 0 ≤ EL ≤ 25.5、105 ≤ Re ≤ 900 和 0范围内改变具有不同振幅 ( EL )、雷诺数 ( Re ) 和纳米颗粒体积分数 (Φ)的通道部分的无量纲长度来进行参数研究≤ Φ ≤ 0.04。

发现

与平面通道相比，波浪通道具有更高的传热速率，超过Re（Re _crit）的临界值，其值随EL而变化；此外，整体热传递随EL降低。对于所有研究的EL值，传热速率随 phi 增加。与平行板通道相比，波浪通道中整体传热增加和相关压降的综合影响以性能因子 ( PF ) 对EL的形式表示。对于EL的最高值(= 25.5)，PF随Re单调递减. 对于较小的EL值（= 5.5 和 11.5）以及EL = 0，PF在较低和较高的Re范围内随Re减小，而在中间Re范围内增加。在所有情况下， φ = 0.04 时的PF均高于基液。随着Re、 φ 和EL的变化，平均努塞尔数对纳米粒子体积分数的敏感性遵循非单调趋势。

实际影响

这项研究发现了太阳能集热器、热交换器和散热器等多种应用的相关性。

原创性/价值

据作者所知，文献中首次报道了纳米流体通过振幅线性变化的波浪通道的强制对流分析。