相邻圆柱/斜坡及其展向间距对平板流动转捩影响的直接数值模拟

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关键词：直接数值模拟；线性模态；相干结构；粗糙元

中图分类号：O357.5文献标志码：A

DOI：10.7652/xjtuxb202508004 文章编号：0253-987X（2025）08-0032-10

Direct Numerical Simulation on the Influence of Adjacent Cylinder/Ramp and Spanwise Spacing on the Transition of Flat Plate Flow

ING Weihao，WANG Zhiheng，HUANG Wenlin， SUN Zhongguo， XI Guang （School of Energy and Power Engineering，Xi'an Jiaotong University，Xi'an 71o049，China）

Abstract： In order to address the issue of unclarified effect of adjacent roughness elements on plate transition，direct numerical simulation was employed to investigate the transition induced by the spanwise arrangement of adjacent roughness elements， comprising cylinders and ramps. These roughness elements were resolved utilizing the embedded boundary method，with spanwise intervals set at 2.5h and 5h ，respectively，where h denotes the height of the roughness elements. The study elucidated the effects of transient and time-averaged flow characteristics，coherent structures， and characteristic modes. Findings indicated that ramps with significant disturbances predominantly influenced the breakdown of hairpin vortices，the onset of transition，and the energy transferred from time-averaged flow to the fluctuating flow. With the ramp neglected，a decrease in spanwise spacing effectively promoted transition. The interplay between roughness elements of varying shapes could generate a more potent nonlinear coherent structure than that observed among elements of uniform shape. The intense disturbance caused by the ramp predominantly contributed to the wall-normal and spanwise fluctuating waves of the coherent structure，rather than to the streamwise fluctuating waves. The interaction between adjacent roughness elements of diverse shapes， facilitated by an optimal reduction in spanwise spacing， promoted the evolution of the nonlinear structure at the central position. This structure could be approximated by several linear modes across the full frequency spectrum. When the spanwise spacing was well-chosen， roughness elements with different shapes might induce low-frequency resonance of nonlinear structures in a region near the downstream，substantially enhancing their evolutionary dynamics.

Keywords： direct numerical simulation; linear mode; coherent structure; roughness elements

从层流到湍流过渡的边界层转捩问题是现代流体力学尚未完全解决的重要研究领域，而粗糙元诱导转捩是其中的重要内容。（剩余12787字）