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

• 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
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650575/
• 关键词: wall turbulence; bedload sediment transport; particle; collision; coefficient of restitution; simulation; Stereo PIV; micro-sensor; 衝突・接触モデル; 直接数値計算法; 力・モーメントの測定

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

为了理解推移质泥沙运动的微观力学，本项目有三个目标：(1)开发和验证一种数值方法来模拟许多固体颗粒在湍流中的运动，(2)开发和验证微力矩传感器，(3)阐明推移质泥沙运动的微观动力学。明确的目标(1)：为了进行设想的类型的模拟，必须开发一个精确的模型来描述水中颗粒之间的作用力，特别是粘性的“润滑”力。为此，我们将玻璃珠子垂直地放在一块不锈钢平板上，其粗糙度从1微米到100微米不等两个数量级。与以前的理论论证相反，我们发现粗糙度降低了恢复系数，并且在空气和水中的降幅相似，这表明能量耗散是由固体材料粗糙内的塑性变形主导的。在另一项工作中，我们提出了Kajishima模拟湍流中固体颗粒的方法的一个重要变体(参考文献[1])。目标(2)：我们的微机械芯片具有横杆结构，能够测量施加在该结构上的力和力矩的所有6个分量。测试颗粒可以安装在其上，并安装在水槽的底部。用半露出床板的颗粒进行的测试已经获得了相当可重复性的信号，RET可达300(参考文献)。目的(3)：我们对带有表面安装半球的光滑床槽流中的湍流流动进行了数值模拟。我们发现半球上的升力、它的阻力和附近的流向速度分量(REF)之间存在着极高的相关性。2)。我们还发现，直径为d+=12的半球上的力的偏斜度与直径为d+=33的半球上的力的偏斜度非常不同。10.关键词

项目成果

A.T.Nguyen, D.V.Dao, T.Toriyama, J.C.Wells, S.Sugiyama: "Measurement of loads acting on a near-wall particle in turbulent water flow by using 6-DOF MEMS-based sensor"Technical Digest of the 20th Sensor Symposium 2003, IEEJ. 139-144 (2003)

A.T.Nguyen、D.V.Dao、T.Toriyama、J.C.Wells、S.Sugiyama：“使用基于 6 自由度 MEMS 的传感器测量作用在湍流水流中近壁粒子上的载荷”2003 年第 20 届传感器研讨会技术摘要

F.Takashima, J.C.Wells, Y.Yamamoto, Y.Kakehi: "On the turbulent flow structures initiating rollup motion of a spherical particle on a water-channel bed"Proc. 3rd JAHR Symposium on River, Coastal, and Estuarine Morphodynamics. 1137-1144 (2003)

F.Takashima、J.C.Wells、Y.Yamamoto、Y.Kakehi：“关于在水道床上引发球形颗粒滚动运动的湍流结构”Proc。

D.V.Dao, T.A.Nguyen, T.Toriyama, J.C.Wells, S.Sugiyama: "A MEMS-based Microsensor to Measure All Six Components of Force and Moment on a Near-Wall Particle in Turbulent Flow"Proceeding of the 12th IEEE International Conference on Solid-State Sensors, Actu

D.V.Dao、T.A.Nguyen、T.Toriyama、J.C.Wells、S.Sugiyama：“基于 MEMS 的微传感器，用于测量湍流中近壁粒子上力和力矩的所有六个分量”第 12 届 IEEE 国际会议论文集

J.C.Wells, K.Kishida, N.Ukai, Y.Himeno, C.V.Nguyen: "Temporally-resolved stereo I.V. in a cross-stream plane in open channel flow, with a comment on the pinhole model for Scheimpflug cameras"Proceedings, 10th International Symposium on Flow Visualization.

J.C.Wells、K.Kishida、N.Ukai、Y.Himeno、C.V.Nguyen：“明渠流中交叉流平面中的时间解析立体声 I.V.，以及对 Scheimpflug 相机的针孔模型的评论”论文集，第 10 届国际会议

Dao, D.V., T.Toriyama, J.C.Wells, S.Sugivama: "Silicon Piezoresistive Six-Degree of Freedom Force-Moment Micro Sensor"Sensors and Materials, International Journal on Sensor Technology. V15(3). (2003)

Dao, D.V.、T.Toriyama、J.C.Wells、S.Sugivama：“硅压阻六自由度力力矩微传感器”传感器和材料，国际传感器技术杂志。