一个基于粗糙元方向比率和空气动力学粗糙度的起动摩阻风速模式  

An improved scheme for modeling wind friction threshold velocity dependent on the aspect ratio of individual element and aerodynamic roughness length

作　　者：梅凡民[1] 王姗 唐丽萱 苏进[2] Mei Fanmin;Wang Shan;Tang Lixuan;Su Jin(School of Environmental and Chemical Engineering,Xi’an Polytechnic University,Xi’an 710048,China;School of Sciences,Xi’an Polytechnic University,Xi’an 710048,China)

机构地区：[1]西安工程大学环境与化学工程学院,陕西西安710048 [2]西安工程大学理学院,陕西西安710048

出　　处：《中国沙漠》2020年第6期98-104,共7页Journal of Desert Research

基　　金：兰州大学西部灾害与环境力学教育部重点实验室开放基金项目;国家自然科学基金项目(41340043,11601411)。

摘　　要：粉尘释放模型对风蚀粉尘气候、生态效应的评价和沙尘天气的预报有重要意义。条件试验表明,MB模式和SL模式存在高估或低估起动摩阻风速的情形,但未得到观测数据的支持。鉴于此,利用风洞实验测量了不同密度(0.0072~0.51)、方向比率(4~25)、孔隙率(0.15~0.75)的粗糙元覆盖的中粗沙床面的起动摩阻风速。结果表明:当空气动力学粗糙度大于1 mm时,MB模式存在高估(相对误差率80%~100%)起动摩阻风速而失效的情形,SL模式存在低估(相对误差率-50%^-20%)起动摩阻风速的情形。基于观测数据本文提出了一个基于粗糙元方向比率、粗糙和光滑床面空气动力学粗糙度比值及裸沙起动摩阻风速的新模式,可以模拟低、中、高密度的粗糙元覆盖床面的起动摩阻风速,模拟的误差在±0.1 m·s-1以内。Improvement in modeling dust emission is very important for predictions of sand-dust storms and climatic and ecological effects of soil-derived dust events. It has not been validated since overestimation from one classical scheme for modeling saltation threshold over roughness surfaces and underestimation from another scheme were found in terms of condition analysis. As a result,wind friction threshold velocities over find-medium sand surfaces with roughness elements with various aspect ratios(0. 25-25),densities(0. 0072-0. 51),and porosities(0. 15-0. 75) were measured in a wind tunnel. It indicates that overestimation(the relative error around 80%-100%)and incorrectness from one scheme and underestimation(the relative error from-50% to-20%)from another scheme will occur as roughness length more than 1 mm. An improved scheme for modeling saltation threshold is proposed here,dependent on aspect ratio of individual element,the ratio of overall aerodynamic roughness to erodible roughness. The new scheme can be applied to predicate wind friction velocity over beds with sparse,medium and dense roughness elements,having very low relative error around ±0. 1 m·s-1.

关 键 词：粉尘释放 起动摩阻风速 方向比率 空气动力学粗糙度 风洞实验 

分 类 号：X169[环境科学与工程—环境科学]