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

本文的主要目的是研究复杂的近壁湍流和非牛顿流体在多孔介质中的流动。紊流研究将集中于研究粗糙度对紊流附壁射流、压力梯度边界层和明渠浅尾流的影响。压力梯度参数的值将从温和到强烈变化。将使用平面和立体粒子图像测速仪（PIV）进行速度测量。瞬时速度场将被用来识别相干结构，并阐明这些结构在各种湍流和表面条件下对湍流产生的动态作用。根据PIV数据，将评估时间平均平均速度的等值线和剖面以及湍流动能和雷诺应力的传输方程中的各项。利用平面激光诱导荧光技术研究了粗糙度对壁面射流和尾流中标量输运和混合过程的影响。壁射流的结果将提供洞察的内部和外部层之间的相互作用，以及这种相互作用是如何修改特定的粗糙度。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理解和高质量的数据集将在未来用于指导精确模型的开发，用于预测具有工程重要性的湍流。多孔介质将包括垂直和平行于矩形通道中的流动放置的丙烯酸棒阵列。杆将仅填充通道的顶壁和底壁之间的空间的一小部分。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。将研究诸如孔隙率、通道高度的填充分数和特定流体等变量对棒内再循环的发生以及平原流到多孔介质中的渗透的影响。该研究将为培养高素质人才提供机会，并为加拿大提供可观的经济效益。

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.