Bluff-body wakes and turbulent flows

“钝体”具有非流线型形状和非常高的阻力系数。钝体周围的流动是复杂的，其特点是有大面积的分离流动，其中流动不遵循体的形状。在机体下游的低压尾迹中，可能是不稳定的，也可能是紊流的，当涡旋周期性地从机体表面释放出来时，就会出现“旋涡脱落”现象。在某些条件下，涡流脱落可能会引起不必要的结构运动，即“流致振动”。我的研究计划的主要科学目标是推进对崖体尾迹的物理理解，其中重点是围绕表面安装的有限高度的崖体的流动，例如有限圆柱，有限方棱镜和屋顶安装的烟囱。我想更好地理解尾迹产生体和局部流场之间的基本关系，以及近尾迹是如何受到身体形状变化、与其他钝体的接近程度以及地平面的存在的影响的。对于安装在屋顶的烟囱（“横流中的高架射流”），我想更好地理解烟囱射流状态是如何影响烟囱和烟囱尾流中的气流所受的力的。

"Bluff bodies" have non-streamlined shapes and very high drag coefficients. Flow around a bluff body is complex, and is characterized by a large region of separated flow, where the flow does not follow the shape of the body. In the low-pressure wake downstream of the body, which may be unsteady or turbulent, the phenomenon of "vortex shedding" occurs as vortices are periodically released from the surface of the body. Under certain conditions, vortex shedding may cause unwanted structural motion known as "flow-induced vibration." The main scientific goal of my research program is to advance the physical understanding of bluff-body wakes, where the emphasis is the flow around surface-mounted, finite-height bluff bodies, such as finite circular cylinders, finite square prisms, and rooftop-mounted chimney stacks. I want to better understand the fundamental relationships between the wake-generating body and the local flow field, and how the near wake is influenced by alterations to the body shape, its proximity to other bluff bodies, and the presence of the ground plane. For the rooftop-mounted stack (an "elevated jet in cross-flow"), I want to better understand how the stack jet flow regimes affect the forces experienced by the stack and the flow in the stack wake. A second scientific goal of my research is to better understand the effects of surface roughness on wall-bounded turbulent shear flows, specifically the plane turbulent wall jet. Turbulent wall jets are encountered in the film cooling of turbine blades and in slotted flaps on airplane wings. For this flow, I want to better understand the effects of surface roughness and Reynolds number on the skin-friction drag acting on the wall. For both main research areas, the expected research contributions will include new experimental data for engineering design work, and new knowledge into the fundamentals of fluid flow behaviour. Both experimental and numerical modeling approaches will be used in the research program.