Study of complex turbulent flows over rough walls and flow of non-newtonian fluid through model porous media

本文的目的是研究复杂的近壁湍流流动和非牛顿流体在多孔介质中的流动。紊流研究将重点研究湍流壁面射流、压力梯度边界层和明渠浅层尾迹的粗糙度效应。压力梯度参数的值将由弱到强变化。平面和立体粒子图像测速（PIV）将用于进行速度测量。瞬时速度场将用于识别相干结构，并将阐明这些结构在各种湍流和表面条件下对湍流产生的动力学作用。从PIV数据，等等值线和剖面的时间平均平均速度和各种项的输运方程湍流动能和雷诺应力将被评估。利用平面激光诱导荧光研究了壁面射流和尾迹中粗糙度对标量输运和混合过程的影响。壁面射流的结果将提供内层和外层之间相互作用的见解，以及这种相互作用是如何被特定粗糙度所改变的。压力梯度实验将提供粗糙度和压力梯度对湍流结构的综合影响的信息。从湍流研究中获得的物理认识和高质量的数据集将在未来用于指导精确模型的开发，以预测具有工程重要性的湍流。多孔介质将包括垂直和平行放置在矩形通道中的丙烯酸棒阵列。这些棒只会填满沟道顶部和底部壁之间的一小部分空间。将研究各种非牛顿流体。将测量流体的流变特性。将使用PIV来研究速度场。将研究孔隙度、通道高度的填充分数和比流体等变量对杆内再循环开始的影响，以及平原流对多孔介质的渗透。这项研究将为培养高素质人才提供机会，并为加拿大带来可观的经济效益。

The objectives of this proposal are to study complex near-wall turbulent flows and flow of non-Newtonian fluid through porous media. The turbulence research will focus on the investigation of roughness effects on turbulent wall jets, pressure gradient boundary layers, and shallow wakes in an open channel. The values of the pressure gradient parameter will be varied from mild to strong. A planar and stereo particle image velocimetry (PIV) will be used to conduct the velocity measurements. The instantaneous velocity field will be used to identify coherent structures, and the dynamic role of these structures on turbulence production in the various turbulent flows and surface conditions will be elucidated. From the PIV data, iso-contours and profiles of the time averaged mean velocity and the various terms in the transport equations for turbulent kinetic energy and Reynolds stresses will be evaluated. A planar laser induced fluorescence will be used to study roughness effects on scalar transport and mixing process in the wall jets and wakes. The wall jet results will provide insight into the interaction between the inner and outer layers, and how this interaction is modified by specific roughness. The pressure gradient experiments will provide information on the combined effects of roughness and pressure gradients on the turbulent structure. The physical understanding obtained from the turbulence research and the high quality data sets will be used in the future to guide the development of accurate models for predicting turbulent flows of engineering importance. The porous media will comprise arrays of acrylic rods placed perpendicular and parallel to flow in a rectangular channel. The rods will fill only a fraction of the space between the top and bottom walls of the channel. A variety of non-Newtonian fluids will be studied. The rheological properties of the fluids will be measured. A PIV will be used to study the velocity field. The effects of variables such as porosity, filling fraction of channel height and specific fluid on onset of recirculation within the rods, and penetration of the plain flow into the porous media will be studied. The research will provide opportunity to train highly qualified personnel and provide substantial economic benefits to Canada.