PIV法および直接数値計算法による流砂のマイクロメカニクスの解明

利用PIV方法和直接数值计算方法阐明流沙的微观力学

基本信息

批准号：
13650575
负责人：
WELLS John C.
金额：
$ 2.05万
依托单位：
Ritsumeikan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

Toward the objective of understanding the micromechanics of bedload sediment transport, the present project had three objectives : (1) Development and validation of a numerical method to simulate the motion of many solid particles in a turbulent flow, (2) Development and validation of a micro force-moment sensor, (3) Clarification of the microdynamics of bedload particle motion.Concerning objective (1) : To perform simulations of the type envisaged, it is necessary to develop an accurate model for the forces between particles in water, in particular the viscous "lubrication" force. To that end,we dropped glass beads vertically onto a stainless steel plate whose roughness was varied over two orders of magnitude, from 1 to 100 microns. Contrary to previous theoretical arguments, we found that roughness decreased the coefficient of restitution, and by an amount that was similar in air and water, which suggests that energy dissipation is dominated by plastic deformation within asperities of the solid material. In other work, we have proposed an important variation of Kajishima's method of simulating solid particles in a turbulent flow (ref. 1 below).Objective (2) : We have micromachined chips with a crossbar structure capable of measuring all 6 components of force and moment applied to the structure. A test particle can be mounted thereon, and installed at the bottom of a water channel. Tests with the particle half-emerging from the bed plate have achieved a fairly reproducible signal down to ReT of 300(ref. 6 below).Objective (3) : We have performed DNS of turbulent flow in a smooth-bed channel flow with a surface-mounted hemisphere. We found an extremely high correlation between the lift on the hemisphere, its drag, and the nearby streamwise velocity component (ref. 2 below). We also found very different skewness of forces on a hemisphere of diameter d+=12 vis-a-vis a diameter of d+=33. 10. KEY WORDS

为了理解床载沉积物传输的微观力学的目的，本项目具有三个目标：（1）模拟数值方法的开发和验证，以模拟许多固体颗粒在湍流流中的运动，（2）微力量运动传感器的开发和验证，（3）对床位粒子运动的准确（1）的准确性（1）阐明，以阐明（3）水中颗粒之间的力，尤其是粘性的“润滑”力。为此，我们将玻璃珠垂直放到一个不锈钢板上，其粗糙度在两个数量级（从1至100微米）上变化。与以前的理论论点相反，我们发现粗糙度降低了恢复的系数，并且在空气和水中相似的量降低了量，这表明能量耗散是由固体物质的垂体内部内部的塑性变形所支配的。在其他工作中，我们提出了Kajishima在湍流中模拟固体颗粒的方法的重要变化（参考文献1）。目标（2）：我们具有具有横杆结构的微机械芯片，能够测量所有6个成分的力和矩矩置于结构上。可以将测试粒子安装在其上，并安装在水通道的底部。从床板中进行半出现的粒子的测试已达到相当可重复的信号，向下降至300（参考文献6）。对象（3）：我们已经在平滑床的流动中进行了湍流的DNS DN，并具有表面安装的半球。我们发现半球上的升力，其阻力与附近的流速速度分量之间存在极高的相关性（下面的参考文献2）。我们还发现，力在直径d+= 12 vis-a-vis a直径为d+= 33的半球上的偏斜度非常不同。 10。关键词