标题： 通过域变换的肋条湍流建模 显示英文标题

标题： Turbulence modeling over riblets via domain transformation

摘要： 数值和实验研究已经证明，精心设计的顺流延伸的肋条在降低壁面摩擦阻力方面具有减阻潜力。 为了支持此类表面波纹的系统设计，最近的研究将控制方程的简化版本与创新的方法相结合，以表征粗糙边界对流动动力学的影响。 值得注意的是，涡粘性增强的线性化纳维-斯托克斯方程的统计响应已被证明能够有效捕捉肋条抑制湍流的能力，量化背景湍流对平均速度的影响，并重现已建立的减阻趋势。 在本文中，我们通过实施用于表面表示的域变换，以及对肋条的小几何参数进行扰动分析，增强了这种无需仿真的方法的灵活性和计算效率。 虽然域变换使微分方程变得复杂，但它提供了精确的边界表示，并通过扰动分析简化控制方程的维度复杂性，从而促进了在高雷诺数下对复杂肋条形状的分析。 我们的方法成功预测了半圆形肋条的减阻趋势，与现有文献一致。 我们进一步利用我们的框架研究受肋条影响的流动机制，并将研究扩展到摩擦雷诺数高达2003的通道流动。 我们的研究结果揭示了在大而尖锐的半圆形肋条上出现的凯尔文-赫姆霍兹滚筒，这些滚筒导致这些几何结构中的减阻效果退化。 此外，我们还研究了肋条对近壁流动结构的影响，重点在于它们对大肋条上顺流延伸结构的抑制作用。 显示英文摘要

摘要： Numerical and experimental studies have demonstrated the drag-reducing potential of carefully designed streamwise-elongated riblets in lowering skin-friction drag. To support the systematic design of such surface corrugations, recent efforts have integrated simplified versions of the governing equations with innovative methods for representing the effects of rough boundaries on flow dynamics. Notably, the statistical response of the eddy-viscosity-enhanced linearized Navier-Stokes equations has been shown to effectively capture the ability of riblets in suppressing turbulence, quantify the influence of background turbulence on the mean velocity, and reproduce established drag-reduction trends. In this paper, we enhance the flexibility and computational efficiency of this simulation-free approach by implementing a domain transformation for surface representation, along with a perturbation analysis on a small geometric parameter of the riblets. While domain transformation complicates the differential equations, it provides accurate boundary representations and facilitates the analysis of complex riblet shapes at high Reynolds numbers by enabling perturbation analysis to simplify the dimensional complexity of the governing equations. Our method successfully predicts drag reduction trends for semi-circular riblets, consistent with existing literature. We further utilize our framework to investigate flow mechanisms influenced by riblets and extend our study to channel flows with friction Reynolds numbers up to 2003. Our findings reveal the emergence of Kelvin-Helmholtz rollers over large and sharp semi-circular riblets, contributing to the degradation of drag reduction in these geometries. Additionally, we examine the impact of riblets on near-wall flow structures, focusing on their suppression of streamwise-elongated structures in flows over large riblets.