论文标题
壁滑的影响层流经过圆柱体的层流
Effect of wall slip on laminar flow past a circular cylinder
论文作者
论文摘要
对经过二维流的数值研究，经过带有滑动壁的密闭圆柱体。一个无尺寸的数字，Knudsen号码（$ kn $）用于描述圆柱墙的滑动长度。所考虑的Reynolds编号（$ re $）和Knudsen编号（$ kn $）范围分别为$ re = [1，180] $和$ kn = [0，\ infty）$。时间平均流量分离角（$ \ bar {θ_s} $），无量纲再循环长度（$ \ bar {l_s} $）和分布在气缸墙上，拖动系数（$ \ bar {$ \ bar {c_d} $）和drag recred（$）上的切入速度（$ \ bar {u_τ} $）。气缸壁上的时间平均切向速度分布非常符合公式$ \ bar {u_τ} = [\fracα{1+βe^{ - γ（π-θ）}+Δ] sin（θ）$，n efeffients（$α$，$β$，$γ$，$γ$，$γ$，$γ$， Several scaling-laws are found, $log(\bar{u_{τmax}})\sim{log(Re)}$ and $\bar{u_{τmax}}\sim{Kn}$ for low $Kn$, ($\bar{u_{τmax}}$ is the maximum tangential velocity on the cylinder's wall), $ log（dr）\ sim {log（re）} $（$ re \ leq45 $和$ kn \ leq0.1 $），$ log（dr）\ sim {log {log（kn）} $（$ kn \ kn \ leq0.05 $）。在低$ re $，$ dr_v $（减少摩擦阻力）是$ dr $的主要来源。但是，$ dr_p $（减少差压力阻力）在$ re $ $ $ $ $ $ $ $ $> \ sim60 $）和关键数字上的$ kn $贡献最高。 $ dr_v $几乎独立于$ re $。
A numerical study of two-dimensional flow past a confined circular cylinder with slip wall is performed. A dimensionless number, Knudsen number ($Kn$) is used to describe the slip length of cylinder wall. The Reynolds number ($Re$) and Knudsen number ($Kn$) ranges considered are $Re = [1, 180]$ and $Kn = [0, \infty)$, respectively. Time-averaged flow separation angle ($\bar{θ_s}$), dimensionless recirculation length ($\bar{L_s}$) and the tangential velocity ($\bar{u_τ}$) distributed on the cylinder's wall, drag coefficient ($\bar{C_d}$) and drag reduction ($DR$) are investigated. The time-averaged tangential velocity distribution on the cylinder's wall fit well with the formula $\bar{u_τ} = [\fracα{1+βe^{-γ(π-θ)}}+δ]sin(θ) $, where the coefficients ($α$, $β$, $γ$, $δ$) are related with $Re$ and $Kn$. Several scaling-laws are found, $log(\bar{u_{τmax}})\sim{log(Re)}$ and $\bar{u_{τmax}}\sim{Kn}$ for low $Kn$, ($\bar{u_{τmax}}$ is the maximum tangential velocity on the cylinder's wall), $log(DR)\sim{log(Re)}$ ($Re\leq45$ and $Kn\leq0.1$), $log(DR)\sim{log(Kn)}$ ($Kn\leq0.05$). At low $Re$, $DR_v$ (the friction drag reduction) is the main source of $DR$. However, $DR_p$ (the differential pressure drag reduction) contributes the most to $DR$ at high $Re$ ($Re>\sim60$) and $Kn$ over a critical number. $DR_v$ is found almost independent to $Re$.
