Advanced modeling of flows with turbulence, multiple phases and complex surfaces

工程师们感兴趣的许多工业和环境流动是湍流和多相的，并且涉及到一个坚实的边界。湍流的特征是由于不同大小和方向的涡流运动而引起的局部速度场的明显随机波动。湍流具有强烈的混合和高输运率的特点，因此具有重要的实用价值。一种重要的多相流是含有固体颗粒的流体的流动。在这种情况下，颗粒的输运是由颗粒所受的流体动力阻力决定的。拟议的研究计划将研究湍流和多相流的特性，重点是流体与固体表面的相互作用。它还将研究与活组织相关的复杂壁面上的非湍流微流体流动。 将研究四种不同的壁面流动形态。第一种流动形态是湍流平面壁面射流，通过引导平行于壁面的射流来形成。对于粗糙表面的壁面，粗糙度对射流的影响还没有完全了解。第二种流动形式是绕过安装在地平面上的有限棱镜。棱镜后面产生的尾迹是复杂的，包含非定常的涡旋结构。这些结构产生的确切机制尚未确定。第三种流动形态是湍流气固两相流动，如气力输送。在这种情况下，颗粒和湍流之间的相互作用是复杂的，很难纳入工程模型中。最终的构型是通过多孔组织支架的微流体流，这有助于生物组织的生长。组织表面的生长和变化是对流动提供的营养物质和机械刺激的反应。 对这些流动模式的研究将为流体如何与不同构型的固体壁相互作用提供新的见解。将使用新的数值和实验方法研究流动，以获得瞬时速度场，并将使用先进的分析工具对其进行处理，以识别相关的流动结构。这些研究不仅将促进我们对流固相互作用的基本理解，而且还将用于改进工程师用于预测工业和环境应用中的平均流动特性的湍流和多相模型。最后，模拟活组织上的流动的能力，随着流动特征的变化而增长和变化，将展示计算流体动力学的潜力，以增强我们对生物医学系统的理解。

Many industrial and environmental flows of interest to engineers are turbulent and multiphase, and involve a solid boundary. A turbulent flow is characterized by apparently random fluctuations in the local velocity field due to eddy motions of different size and orientation. Turbulent flows are of great practical importance, since they are characterized by intense mixing and high transport rates. One important multiphase flow is the flow of a fluid containing solid particles. In this case, the particle transport is dominated by the hydrodynamic drag forces on the particles. The proposed research program will investigate the characteristics of turbulent and multiphase flows, with a focus on the fluid interaction with the solid surfaces. It will also study non-turbulent, micro-fluidic flows over complex walls associated with living tissues. Four different wall flow configurations will be studied. The first flow configuration is a turbulent plane wall jet, created by directing a jet parallel to a wall. For walls with a rough surface, the effect of the roughness on the jet is not yet fully understood. The second flow configuration is flow over a finite prism mounted on a ground plane. The wake created behind the prism is complex and contains unsteady vortical structures. The exact mechanism for the generation of these structures has not yet been determined. The third flow configuration is that of turbulent gas-particle flow, such as occurs in pneumatic transport. In this case, the interaction between the particles and the turbulence is complex and difficult to incorporate in engineering models. The final configuration is micro-fluidic flow through a porous tissue scaffold which facilitates the growth of biological tissue. The tissue surface grows and changes in response to the nutrients and mechanical stimulation supplied by the flow. The study of these flow paradigms will provide new insight as to how a fluid interacts with solid walls of different configurations. The flows will be studied using novel numerical and experimental methods to obtain the instantaneous velocity fields, which will be processed using advanced analysis tools to identify the pertinent flow structures. These studies will not only advance our fundamental understanding of fluid-solid interactions, but will also be used to improve the turbulence and multiphase models used by engineers to predict mean flow properties in industrial and environmental applications. Finally, the ability to simulate flow over a living tissue, which grows and changes in response to the flow characteristics, will demonstrate the potential of computational fluid dynamics to enhance our understanding of biomedical systems.