Solid barriers for windblown sand mitigation: Aerodynamic behavior and conceptual design guidelines

Abstract

Protection from windblown-sand is one of the key engineering issues for construction and maintenance of human infrastructures in arid environments. In the last century, several barriers with different shapes have been proposed in order to overcome this problem, but literature lacks of a systematic performance quantitative analysis, and the key geometric parameters that promote sedimentation have not been yet recognized. A deep understanding of the aerodynamics effects of sand barrier on the flow is an unavoidable step to achieve these objectives. The present computational study aims to comparatively analyze different kinds of windblown sand mitigation solid barriers, clarify their working principles, extract from the aerodynamics analysis key geometrical features of the barriers and relate them to the sand trapping performances. Approximated metrics for performance assessment are introduced using aerodynamic parameters. The performances of an innovative solid barrier and the ones of commonly used solid barriers are compared in terms of these metrics. The effects of incoming wind velocity profiles on sand trapping performances are evaluated as well. An empirical dimensionless performance estimator is proposed and used to provide general design guidelines.

Shield for Sand: An Innovative Barrier for Windblown Sand Mitigation

“…S4S barrier is patented [33]. The concept is proved by assessing its working principle and aerodynamic performances by means of Computational Fluid Dynamics (CFD) simulations [17]. This part corresponds to the conceptual and preliminary design phases in Civil Engineering.…”

“…For the sake of conciseness, the preliminary estimation of sand trapping performance of S4S barrier is compared with the one resulting from the Straight Vertical Wall (SVW), taken as a reference case. Interested readers can refer to Bruno et al [17] for a wider comparative analysis of the sand trapping performance among a number of other patented solid barriers, e.g. [27,28,29].…”

“…They are scarcely investigated in the scientific literature [16]. They induce an upwind vortex in the mean wind flow, and sand sedimentation mainly occurs on the upwind strip [17]. Their trapping performances are expected to decrease with increasing levels of accumulated sand.…”

Application of Boundary Layer Displacement Thickness in Wind Erosion Protection Evaluation: Case Study of a Salix psammophila Sand Barrier

“…Surface roughness refers to the height at which the surface layer wind profile goes to zero [9]. It is a measure of the decreasing effect of the surface on the wind speed, which affects absolute and relative sediment transport by influencing the threshold wind velocity [10,11,12]. Surfaces that exhibit high resistance to wind erosion display large surface roughness values [13,14,15].…”

Effects of Wind Velocity and Nebkha Geometry on Shadow Dune Formation

“…Parameters such as the fluid velocity, direction, pressure, and shear stress in secondary airflow are altered by the topography of obstacles (Walker & Nickling, 2002;Wang & Huang, 2017). Secondary airflow differs in energy and direction due to variations in the geometry and alignment of obstacles and the wind regime (e.g., wind velocity, wind direction, and angle of incidence; Escauriaza & Sotiropoulos, 2011;McKenna-Neuman and Bédard, 2015;Meire et al, 2014;McKenna-Neuman et al, 2015;Vinuesa et al, 2015;Bruno et al, 2018;Kindere & Ganapathisubramani, 2018;Sun & Huang, 2018;He et al, 2018). Although the relationships between the geometric parameters of the obstacles, the wind velocity, and the length of flow reattachment and recovery have been reported previously (Clemmensen, 1986;Gillies et al, 2014;Gunatilaka & Mwango, 1987;Hesp, 1981 ;Hesp & Smyth, 2017), questions remain about the sensitivity of these secondary airflow structures to changes in wind velocity, the geometry of the obstacles, and the subsequent shadow dune formation.…”