Asymmetric unstable natural convection in an open-ended vertical channel with hot-cold walls

IF 6.2 2区工程技术 Q1 MECHANICS

International Communications in Heat and Mass Transfer Pub Date : 2026-03-01 Epub Date: 2026-01-19 DOI:10.1016/j.icheatmasstransfer.2026.110568

Chung-Gang Li

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Abstract

The unstable flow phenomena induced by natural convection in an open-ended vertical channel with an asymmetric hot-cold wall configuration are numerically investigated. Unlike classical vertical channel flows, where buoyancy-driven motion remains steady at moderate Rayleigh numbers (Ra = 5.23 × 10⁵–4.18 × 10⁶), the present configuration exhibits pronounced unsteady behavior due to the interaction of counter-rotating flows adjacent to opposing thermal boundaries. The Grossmann–Lohse (GL) theory, originally developed for horizontal Rayleigh–Bénard convection, is found to effectively characterize the kinetic and thermal dissipation structures in this asymmetric vertical system. These instabilities enhance heat transfer by approximately 20%, indicating a distinct scaling behavior from conventional channel flow. A compressible solver with absorbing and non-reflecting boundary conditions is employed to accommodate bidirectional inlet–outlet flow without prescribing the flow rate.

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具有冷热壁的开放式垂直通道中的不对称不稳定自然对流

对具有非对称冷热壁结构的开放式垂直通道中自然对流引起的不稳定流动现象进行了数值研究。与经典的垂直通道流动不同，在传统的垂直通道流动中，浮力驱动的运动在中等瑞利数（Ra = 5.23 × 105-4.18 × 106）下保持稳定，由于靠近相反热边界的反向旋转流动的相互作用，目前的结构表现出明显的不稳定行为。Grossmann-Lohse （GL）理论，最初是为水平rayleigh - b纳德对流而发展起来的，被发现可以有效地描述这种不对称垂直系统的动力学和热耗散结构。这些不稳定性提高了约20%的传热，表明与传统通道流动相比有明显的结垢行为。采用一种具有吸收和非反射边界条件的可压缩求解器，在不规定流量的情况下适应双向进出口流动。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

International Communications in Heat and Mass Transfer 工程技术-力学

CiteScore

11.00

自引率

10.00%

发文量

648

审稿时长

32 days

期刊介绍： International Communications in Heat and Mass Transfer serves as a world forum for the rapid dissemination of new ideas, new measurement techniques, preliminary findings of ongoing investigations, discussions, and criticisms in the field of heat and mass transfer. Two types of manuscript will be considered for publication: communications (short reports of new work or discussions of work which has already been published) and summaries (abstracts of reports, theses or manuscripts which are too long for publication in full). Together with its companion publication, International Journal of Heat and Mass Transfer, with which it shares the same Board of Editors, this journal is read by research workers and engineers throughout the world.