Turbulent flow over walls and around solid objects

提出的研究方案采用数值和实验相结合的方法来研究湍流。湍流是工业和环境应用中最普遍的流动形式，其特征是动量和标量量的输运水平增强。通常，湍流涉及到固体表面的存在，这就极大地改变了湍流结构，使输运特性更加复杂，难以预测设计目的。提出的数值模拟和实验将增强我们对符合这种情况的流动的基本理解。该研究将在四个具体项目的背景下进行，所有这些项目都与固体表面上的湍流有关。第一个应用考虑了附面层流动中有限圆柱后面的尾迹。特别令人感兴趣的是紧靠在汽缸后面的复杂尾迹——或紊流区域。这个流场景在某些方面类似于一个短排气堆栈。第二个流考虑平面壁面射流在一个平坦的表面上，这个表面可以是光滑的，也可以是粗糙的。对于粗糙表面，壁面射流的表面摩擦阻力行为尚未得到很好的理解。请注意，在某些方面，有限圆柱体类似于表面粗糙度的单个元素。要考虑的第三种流动是带有固体颗粒的气体或液体的多相流。在这种情况下，固体表面在流体中运动，固体颗粒会产生小的尾迹，并相互作用。这种流动情况涉及颗粒材料的气动输送，如在一些农业机械应用中，以及采矿应用中的液体浆流。第四个项目是最新颖的，涉及通过多孔组织支架的流动，这是一个正在发展的生物医学应用。提出的研究计划将在萨斯喀彻温大学机械工程流体动力学组内进行。它将有助于推进我们的基本理解，并解决加拿大工业面临的一些紧迫的技术挑战。

The proposed research program uses both numerical and experimental methods to study turbulent flow. Turbulence is the most prevalent flow regime in industrial and environmental applications, and is characterised by enhanced levels of transport for momentum and scalar quantities. Often, turbulent flow involves the presence of a solid surface, which then significantly modifies the turbulence structure and makes the transport characteristics more complex to predict for design purposes. The numerical simulations and experiments being proposed will enhance our fundamental understanding of flows that fit this scenario. The research will be pursued in the context of four specific projects all of which relate to turbulent flow over a solid surface. The first application considers the wake behind a finite cylinder mounted in a boundary layer flow. Of special interest is the complex wake -- or region of disturbed flow -- immediately behind the cylinder. This flow scenario in some ways resembles a short exhaust stack. The second flow considers a plane wall jet over a flat surface, which can be either smooth or covered with surface roughness. The behaviour of the skin friction drag on the wall jet for rough surfaces is not yet well understood. Note that in some ways a finite cylinder resembles a single element of surface roughness. The third flow to be considered is the multiphase flow of a gas or liquid with solid particles. In this case, the solid surface is moving through the fluid, and the solid particles will generate small wakes as well as interact with each other. This flow scenario relates to pneumatic conveyance of granular material as in some agricultural machinery applications and liquid slurry flow in mining applications. The fourth project is the most novel and pertains to flow through a porous tissue scaffold, which is a developing biomedical application. The research program being proposed will be conducted within the fluid dynamics group in Mechanical Engineering at the University of Saskatchewan. It will serve to advance our fundamental understanding and also address some pressing technical challenges being encountered by Canadian industry.