Friction velocity

The momentum flux and friction velocity increase with speed .

动量通量和摩擦速度随风速增加。

The roughness length will vary little along with wind speed and friction velocity when the wind speed increases to some extent .

当风速增大到一定程度时，粗糙度随着风速和摩擦速度变化都不明显。

Field Observation of Dust Threshold Friction Velocity on Different Types on Farmland Surfaces

不同类型农田地表粉尘起动摩阻风速的野外观测

Various methods to determine the friction velocity u in steady uniform flows are analyzed and then compared based on experimental data .

2通过水槽试验资料分析，论述比较了恒定均匀流摩阻流速u的各种研究方法，其取值将直接影响卡门常数κ、积分常数a或b、尾流系数∏及悬浮指数z等参数。

It is found that : 1.the effect of sidewall should be considered when using global resistance method to estimate the friction velocity ;

结果表明：（1）利用阻力平衡法计算摩阻流速时应考虑边壁影响；

Experimental analysis on influence from sudden change of roughness of open channel bottom on friction velocity of turbulent flow and wall shear stress ;

模拟计算了薄板坯连铸过程中的紊流速度场、温度场及溶质场分布，计算分析了拉速变化对三场及凝固过程的影响。

Wind velocity and roughness length influence the friction velocity , the range of average friction velocity is 0.058 ~ 0.092m/s .

摩阻风速受风速和地表粗糙度的影响，日平均摩阻风速最大变化范围是0.058～0.092m/s。

According to the micro-aggregates size distribution parameter 、 roughness length from the simulation of ground situation threshold friction velocity and friction wind speed ;

由表土微团粒粒度分布参数、地表状况等模拟粗糙度、起动摩阻风速和摩阻风速；

The threshold friction velocity over the Loess Plateau depends on the wind direction , due to the complex terrain and inhomogeneous surface .

由于受地形及非均匀下垫面的影响，黄土高原的临界起沙摩擦速度与风向有关。

Calculating Friction Velocity from Data by a Ship-borne Supersonic Anemometer ; The computer performs these calculations with surprising speed .

由船载超声风速仪数据计算摩擦速度计算机以惊人的速度完成这些演算。

Some relationships of roughness length , friction velocity and resistance coefficient with wind velocity and wave height in neutral stratification have been given .

给出了中性层结时水面粗糙度、动力摩擦速度及阻力系数与风速和浪高的关系。

Using the data of the wind gradient observation on oil platform in Bohai sea , the sea surface friction velocity and roughness under different wind conditions were calculated .

本文用海上石油平台上观测的风梯度资料，计算了在不同风况下海面摩擦速度和粗糙高度。

The large roughness length of the Loess hilly dunes and the large interparticle cohesion for the clay soil texture increases the local friction velocity .

黄土丘陵沟壑区的地表粗糙度值和土壤粒子间的相互作用力较大，从而导致了较大的临界起沙摩擦速度。

For the single size bed , we get the relationship between wind speed and the friction velocity and Fourier nodes , and determine the value of the number of nodes .

在单一粒径下，得到了风速与摩阻速度和傅里叶节点数之间的关系，进而确定了节点数的取值。

The numerical model of atmospheric boundary layer suggested by Blackadar is extended to the case over water , in which the roughness of water is a function of friction velocity .

本文将Blackadar的中性大气边界层数值模式推广到水面上的大气边界层，其中粗糙度是摩擦速度的函数。

The results show that the aerodynamic roughness length of gravel bed is a function of gravel size , coverage , free velocity , friction velocity and the atmospheric stratification stability ;

得出以下结论：戈壁风蚀面上空气动力学粗糙度长度与砾石粒径、高度、覆盖度、自由风速、摩擦速度以及大气层结稳定度有关；

The difference of threshold friction velocity at desert and oasis results in that the occurring frequency of the dusty weather at oasis is more than that at desert .

农田和沙地起沙临界摩擦速度的差异，导致绿洲站沙尘天气发生的频数比沙漠站大；

Furthermore , average values of momentum and scalar ( sensible heat ) roughness lengths as well as changes of scalar roughness length with friction velocity are determined by utilizing the data .

同时，还用该资料给出了动量和标量粗糙度（感热粗糙度）长度的平均值及其标量粗糙度随摩擦速度的变化关系。

Both the ratio of friction velocity to free stream wind velocity and the thickness of airflow are subject to the sidewall effect , showing the increase trend with the decreasing aspect ratios .

随着风洞宽高比的减小，断面内中垂线上的气流摩阻速度与自由流速的比值以及受风洞边壁影响的气流厚度均增大。

Based on the measured data , the change of the friction velocity of turbulent flow and the characteristics of the wall shear stress under different sudden roughnesses and different water depths are analyzed herein .

通过实测资料分析不同糙率突变和不同水深的紊流摩阻流速变化情况和水流的壁面切应力的特点。

The surface heating flux can induce the surface wind speed , friction velocity , and stratification stability strengthening at day and weakening at night and so bring the fluctuating of dust storm intensity .

地面热通量能够导致地面风速、层结不稳定度、地面摩擦速度等沙尘暴重要影响因子出现白天增强、夜间减弱的变化，进而影响沙尘暴的强度波动。

We also simulate the vertical mass flux and the horizontal mass flux of particles with the variation of the friction velocity . Compared with the experimental values , both of them are in good agreements .

同时我们模拟得到了跃移运动时，颗粒的垂直质量通量和水平质量通量随摩阻速度的变化规律，与实验值相比较，两者非常吻合。

Due to the time lags between the friction velocity and the bed-load transport , the relation of sediment transport intensity Φ and the flow parameter ψ is no longer unique in unsteady flows .

非恒定流推移质输沙率与水流强度的变化并不同步，Φ与ψ之间不再是一一对应的关系；

While the friction velocity is between 0.108 ~ 0.136m / s , though the simulation one is 2 & 6 times more than observed dust emission flux , it can reflect the reality best .

当平均摩阻风速在0.108～0.136m/s范围内时，模拟粉尘释放通量与观测值最为相似，约为观测粉尘释放通量的2～6倍。

After reviewing the history and the present status of the studies in U and air-sea interaction , we report a recently developed method to measure friction velocity from data by a ship-borne supersonic anemometer .

本文在综述U及海-气交换的研究历史和现状之后，报告了我们新近提出的一种计算由船载超声风速仪数据测量摩擦速度U的新方法。

The roughness length of vegetation cover surface depends on the type , height , coverage of the vegetation , zero-plane displacement height , free velocity , friction velocity and the atmospheric stratification stability .

植被覆盖面空气动力学粗糙度长度取决于植被类型、植被高度、覆盖度、零平面位移高度、自由风速、摩擦速度以及大气层结稳定度。

In addition , the effects of such factors as the friction velocity , the roughness height and the magnitude of grain and their regularities are studied in detail on the structure of windblown sand flow .

进一步详细研究了影响风沙流结构的主要因素，如风速分布、地表粗糙度、沙粒粒径等对风沙流结构的影响方式和规律。

We established the stochastic model of threshold friction velocity , and derived an analytical expression of the threshold friction velocity with random variables ( the eccentricity , the eccentricity angle , support angle and contact angle ) .

建立了临界启动风速的随机模型，推导出含有随机变量（偏心距、偏心角、支持角以及接触角）的临界启动风速的解析表达式。

With the examples of Gobi and oasis in Dunhuang , the critical friction velocity of dust emission by wind erosion and the particle size distribution of surface soil during the wind erosion were analyzed in this paper .

以敦煌地区的戈壁和绿洲为例，对地表土壤风蚀起沙的临界摩擦速度及其变化特征和风蚀起沙过程中地表土壤的粒子尺度分布及其对垂直尘粒通量的影响进行了分析研究。

Furthermore , under pure wind sea regimes , when the atmosphere near the sea surface is unstable , the normalized error of Dyers ' scheme on friction velocity is the least , only of 8.47 % .

并且在纯风浪海面状况下，当近海层大气处于不稳定层结时，Dyer74方案计算的摩擦速度相对EC直接测量值的归一化误差最小，仅为8.47%，能够较好的估计近海层摩擦速度。