边界层流动中表面粗糙度转变后内部边界层高度、壁面剪应力与平均速度的耦合解析模型
Coupled Analytical Model for the Internal Boundary Layer Height, Wall Shear Stress and Mean Velocity Behind a Surface Roughness Transition in Boundary-Layer Flow
- Indian Institute of Technology Hyderabad（印度理工学院海德拉巴分校）
机构由 AI 辅助整理，请以论文原文为准。
中文总结 AI 辅助
提出耦合解析模型，结合三层速度公式与修正扩散类比，预测粗糙度转变后IBL高度、壁面剪应力及平均速度，经十二个数据集验证，准确适用于光滑-粗糙双向转变。
中文摘要 AI 辅助
本文开发了一个耦合解析框架，用于预测中性大气边界层中表面粗糙度转变下游的内部边界层（IBL）高度、壁面剪应力及平均速度剖面。该新模型将三层解析速度公式与针对IBL增长率的修正扩散类比相结合。扩散类比将IBL增长率与湍流扩散及平均垂直平流联系起来。我们的公式修正了先前模型中的物理不一致性，该先前模型假设湍流扩散仅受上游表面条件控制，且由流线位移引起的特征流向速度差与距粗糙度转变的下游距离无关。关键模型参数，即湍流扩散系数和涡粘性增强系数，被建模为上游至下游空气动力学粗糙度长度比的函数。该耦合模型连同其他三个解析模型，针对涵盖广泛粗糙度比的十二个数据集进行了测试，这些数据集包括风洞实验和大涡模拟。新模型准确预测了所有评估的上游和下游粗糙度组合下的壁面剪应力、平均速度和IBL高度，适用于光滑到粗糙及粗糙到光滑的转变。
英文摘要
A coupled analytical framework is developed to predict the internal boundary layer (IBL) height, wall shear stress and the mean velocity profile downstream of a surface roughness transition in a neutral atmospheric boundary-layer. The new model combines a three-layer analytical velocity formulation with a modified diffusion analogy for the IBL growth rate. The diffusion analogy links the growth rate of the IBL to turbulent diffusion and to mean vertical advection. Our formulation rectifies physical inconsistencies in a previous model that assumed that the turbulent diffusion is controlled only by the upstream surface conditions and that the characteristic streamwise velocity difference caused by streamline displacement is independent of downstream distance from the roughness transition. Key model parameters, namely the turbulent diffusion coefficient and the eddy viscosity augmentation coefficient, are modelled as functions of the upstream-to-downstream aerodynamic roughness length ratio. The coupled model, along with three other analytical models, is tested against twelve datasets covering a wide range of roughness ratios, including wind-tunnel experiments and large-eddy simulations. The new model accurately predicts wall shear stress, mean velocity, and IBL height for all combinations of upstream and downstream roughness values evaluated, for both smooth-to-rough and rough-to-smooth transitions.
