Direct numerical simulations of turbulent channel flow over ratchet roughness

IF 2 3区工程技术 Q3 MECHANICS

Flow, Turbulence and Combustion Pub Date : 2022-08-09 DOI:10.1007/s10494-022-00352-8

Angela Busse, Oleksandr Zhdanov

引用次数: 4

Abstract

The influence of the orientation of ratchet-type rough surfaces on their fluid dynamic roughness effect is investigated using direct numerical simulations of turbulent channel flow at \(Re_{\tau }=395\). The ratchet length-to-height ratio is varied from \(\ell /k=2\) to 16 for a fixed ratchet height of \(k/\delta =0.1\) where \(\delta\) is the mean channel half-height. The results show that both roughness function and mean flow and turbulence statistics strongly depend on the ratchet orientation. Existing empirical formulae, which estimate the roughness function \(\Delta U^+\) or the equivalent sand-grain roughness \(k_s\) based on surface-slope related parameters such as the effective slope or the Sigal-Danberg parameter, fail to accurately predict the differences between ratchet surfaces with high windward slopes and ratchet surfaces with high leeward slopes.

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棘轮粗糙度上湍流通道流动的直接数值模拟

通过对\(Re_{\tau }=395\)湍流通道流动的直接数值模拟，研究了棘轮型粗糙表面的取向对其流体动力粗糙度效应的影响。对于固定的棘轮高度\(k/\delta =0.1\)，棘轮长高比从\(\ell /k=2\)变化到16，其中\(\delta\)是平均通道半高。结果表明，粗糙度函数、平均流量和湍流统计量都强烈依赖于棘轮方向。现有经验公式基于有效坡度或Sigal-Danberg参数等表面坡度相关参数估算粗糙度函数\(\Delta U^+\)或等效沙粒粗糙度\(k_s\)，无法准确预测高迎风坡度棘轮面与高背风坡度棘轮面之间的差异。

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

Flow, Turbulence and Combustion 工程技术-力学

CiteScore

5.70

自引率

8.30%

发文量

审稿时长

2 months

期刊介绍： Flow, Turbulence and Combustion provides a global forum for the publication of original and innovative research results that contribute to the solution of fundamental and applied problems encountered in single-phase, multi-phase and reacting flows, in both idealized and real systems. The scope of coverage encompasses topics in fluid dynamics, scalar transport, multi-physics interactions and flow control. From time to time the journal publishes Special or Theme Issues featuring invited articles. Contributions may report research that falls within the broad spectrum of analytical, computational and experimental methods. This includes research conducted in academia, industry and a variety of environmental and geophysical sectors. Turbulence, transition and associated phenomena are expected to play a significant role in the majority of studies reported, although non-turbulent flows, typical of those in micro-devices, would be regarded as falling within the scope covered. The emphasis is on originality, timeliness, quality and thematic fit, as exemplified by the title of the journal and the qualifications described above. Relevance to real-world problems and industrial applications are regarded as strengths.