An Experimental Study on Splash Functions of Natural Sand‐Bed Collision

Abstract

The interaction between sand particles and sand bed is a key part for the study of wind‐blown sand. The splash functions obtained from experimental observations are of great significance to help us understand relevant physical processes. Due to the adoption of substitute material in experiment and immoderate assumptions in numerical simulation, the results of previous studies are still debatable. This paper experimentally studies on splash functions of natural eolian sand particles by using a self‐developed particle emission system to simulate the splash process. Based on the high‐speed photography technique, the distribution of the angle, speed, and number of the liftoff particles and its quantitative characterization are obtained. The mathematical expectations of relevant variables from this work are comparable with existing results but are quantitatively different from the measured data of substitute particles or the numerical simulated results. More importantly, the detailed statistical characteristics of the natural eolian sand splash function are also extracted from our experimental data, which are really significant for elaborative wind‐blown sand study in the future.

Discrete Element Simulation on Sand-Bed Collision Considering Surface Moisture Content

“…Figure 8 presents the restitution coefficient e r of incident grains in sand-bed collisions under different surface moisture in times of 0.15 s. We first compare our numerical simulation results with previous experimental results under a flat surface condition. Simulation results show that the e r of incident grain distributes in the range from 0.5 to 0.6 when the surface is dry, and is consistent with the previous studies from Anderson et al [34] and Chen et al [47]. The reason that our e r results smaller than that of Zhou et al [35] may be the different conditions and materials.…”

“…A particle flow analysis program Particle Flow Code (PFC) is used to simulate the sand-bed collision process in this work. The saltation sand grains in aeolian sand transport process move mainly downwind and vary in non-obvious way along the spanwise direction, which can be approximated as a two-dimensional motion [47]. By comparing with the experimental results, the 2D simulation method has proved to be highly accurate and are widely performed in the numerical simulation of sand-bed collision [34,35,38], so do this work.…”

The Physics of Sediment Transport Initiation, Cessation, and Entrainment Across Aeolian and Fluvial Environments

“…The collision process between an incident particle and a static granular packing has been investigated in many experimental (Ammi et al, ; Bachelet et al, ; Beladjine et al, ; Chen et al, ; Clark et al, , ; Clark, Petersen, et al, ; Mitha et al, ; Nishida et al, ; Oger et al, ; Rioual et al, , ; Tanaka et al, ; Werner, ) and theoretical (Anderson & Haff, , ; Bourrier et al, ; Crassous et al, ; Comola & Lehning, ; Duan, Zhu, & Zheng, ; Haff & Anderson, ; Ho et al, ; Huang et al, ; Kok & Renno, ; Lämmel et al, ; McElwaine et al, ; Namikas, ; Oger et al, , ; Tanabe et al, ; Valance and Crassous, ; Werner & Haff, ; Xing & He, ; Zheng et al, , ) studies in order to better understand aeolian saltation transport and other geophysical phenomena (e.g., rockfall Bachelet et al, ; Bourrier et al, ); see also (Dong et al, ; Gordon & McKenna Neuman, , ; McEwan et al, , ; Nalpanis et al, ; Rice et al, , ; White & Schulz, ; Willetts & Rice, , ) for collision statistics during ongoing aeolian saltation transport. In typical experiments, a spherical incident particle of diameter and mass is shot (e.g., by an airgun) at a given speed and angle onto a static packing of spheres of the same size.…”

“…Chen et al () investigated the particle‐bed collision process for natural sand particles, which exhibit nonspherical shapes and nonuniform particle size distributions. They found significant quantitative and qualitative deviations from the laws describing spherical, uniform particles.…”

Transition from Saltation to Collisional Regime in Windblown Sand

“…One plausible explanation for the overestimation of the simulated mass flow rate may be found in the simplified descrip-tion of the granular phase (e.g., spherical shape, simple visco-elastic model for particle-particle interactions). In particular, the particle shape can significantly affect the mass flow rate as mentioned in [19,20]. Additionally, the turbulent flow model employed in the simulations which is based on classical mixing turbulent length could be eventually improved to account for the possible damping of the turbulence by the saltating particles.…”