考虑边界层自由风速的粗糙床面跃移通量模式
The saltation model for roughness surface incorporating effect of free wind velocity over boundary layer
徐杨 1梅凡民 1朱海波2
作者信息
- 1. 西安工程大学 环境与化学工程学院,陕西 西安 710048
- 2. 杨凌职业技术学院,陕西 杨凌 712100
- 折叠
摘要
用于粗糙床面的风沙天气预报的跃移通量模式主要考虑了床面的空气动力学粗糙度对跃移通量的影响而最近的研究表明边界层自由风速等因素也会影响跃移强度.鉴于此,根据边界层风洞测试的6组密实粗糙元和3组孔隙粗糙元覆盖床面在不同自由风速下的跃移通量,确认了前人的基于床面空气动力学粗糙度的跃移通量模式的不确定性,发现了实测的跃移通量是粗糙床面空气动力学粗糙度、边界层自由风速和调整摩阻风速(摩阻风速与起动摩阻风速的函数)的复合函数,此结果可能与粗糙床面风沙边界层属于非常应力层有关.
Abstract
Two previous saltation models for roughness surface focus on effect of aerodynamic roughness length on sand transport rate,disagreement with recent investigations which find that such the factor as free wind veloci-ty over boundary layer also affects significant saltation flux.Thus,saltation fluxes under various free velocities over 9 roughness surfaces were observed in a blown-sand wind tunnel to develop new model,including the 6 sand surfaces covered with compact roughness elements,and the 3 sand surfaces with porous elements.We find that there exists a significant gap between the observed and computed saltation fluxes by the traditional mod-els,and that the new saltation model is better since it incorporates the ensemble effects of roughness length,free wind velocity and the modified wind friction(function of wind friction threshold velocity and wind friction veloc-ity)on saltation.The effect of free wind velocity on saltation flux could be related with the variation of total shear stress over roughness surface with height.
关键词
跃移通量/自由风速/粗糙元/起动摩阻风速/摩阻风速Key words
saltation flux/free wind velocity/roughness element/wind friction threshold velocity/wind fric-tion velocity引用本文复制引用
出版年
2024
NETL
NSTL
万方数据