Toward a wall-stress model for LES over rough boundaries ; contributions to experimental and simulation technology

建立粗糙边界上 LES 的壁应力模型；

基本信息

批准号：
15560448
负责人：
WELLS John C.
金额：
$ 2.11万
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：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15560448/
关键词：
Turbulence Wall Stress Microsensor Bedload Particle Image Velocimetry Simulation turbulence L.E.S.wall stress P.I.V.Fictitious Domain simulation curved wall pressure drag Velocity microsensor two-phase flow numerical simu

项目摘要

To contribute to research on simulation of wall turbulence, the present research project has developed relevant measurement technology, and has proposed a hybrid LES-RANS wall-stress modeling technique and a new fictitious-domain method for simulating turbulent flow with highly concentrated dispersed particles.Concerning measurement technique, we have developed Stereo PIV (Particle Image Velocimetry) as applied to an open water-channel. First, we pointed out some simple but new aspects of camera calibration. Next, we proposed a new image-processing Technique to directly measure the rate of shear at a wall, both as seen by a single camera, and as reconstructed in 3D from two camera views. This "PIV/Interface Gradiometry" technique was successfully applied to experimental images from a sinusoidal wall. Such basic contributions will facilitate application of (stereo) PIV to regions near possibly complex boundaries.To allow numerical simulation of solid-liquid two-phase flow near a sediment bed, we extended Kajishima's fictitious-domain technique to handle cases of high particle concentration. Tests on "closed" and "open" rotating drums, partially filled with glass beads, gave good agreements on bed angles and other important parameters. Following these tests, we considered a biperiodic "minimal" turbulent channel containing 1500 spherical beads. Parameters were adjusted to yield particle Reynolds number around 15, and nondimensional shear stress (Shields parameter) in the range 0.06 1.1. Over this range, results for sediment flux agreed to within 20% with the prediction of the Meyer-Peter Mueller equation.To contribute to the unresolved theoretical issues related to LES over a boundary of complex shape, the PI has also derived an equation for the pressure drag on a "patch" of wall in terms of the advection of vorticity nearby.

To contribute to research on simulation of wall turbulence, the present research project has developed relevant measurement technology, and has proposed a hybrid LES-RANS wall-stress modeling technique and a new fictitious-domain method for simulating turbulent flow with highly concentrated dispersed particles.Concerning measurement technique, we have developed Stereo PIV (Particle Image Velocimetry) as applied to an open water-channel.首先，我们指出了相机校准的一些简单但新方面。接下来，我们提出了一种新的图像处理技术，以直接测量墙壁上的剪切速率，既可以通过单个相机都可以看到，又可以从两个相机视图中重建3D。这种“ PIV/界面级别计量学”技术成功地应用于正弦壁的实验图像。这种基本贡献将促进（立体）PIV在可能复杂边界附近的区域中应用。为了允许在沉积物床附近固体液的两相流量进行数值模拟，我们扩展了Kajishima的虚拟域技术来处理高颗粒浓度的病例。在“封闭”和“打开”的旋转鼓上进行的测试部分充满了玻璃珠，在床角和其他重要参数上提供了良好的协议。经过这些测试，我们考虑了一个双层“最小”湍流通道，其中包含1500个球形珠。将参数调整为在15左右的粒子雷诺数中产生颗粒雷诺数，而无二维剪应力（SHIELDS参数）在0.06 1.1范围内。在此范围内，沉积物通量的结果同意在20％以内，并预测了Meyer-peter Mueller方程。为有助于在复杂形状的边界上与LES相关的未解决的理论问题，PI还得出了在附近涡度方面的“墙面”墙壁上的压力阻力的方程式。