Laser Doppler velocimeter measurements of flow field around a bluff body

Abstract

Abstract Greater understanding of the details of the flow fields around bluff bodies and the separated regions associated with these flows is necessary to advance the knowledge of fluid–structure interactions. These mechanisms are particularly important in wind engineering in determining design pressures on structures. In almost all instances the maximum design pressure occurs in regions of separated flow. The details of the flow in these separated regions and the criteria for physical or numerical modeling of the flows in these regions are not well understood. Measurements have been conducted using a laser Doppler velocimeter (LDV) to examine the structure of separated shear layers and the associated regions of separated flow. A LDV is an important tool for this application. A LDV system is capable of measuring reversing flows and consequently high local turbulent intensities. Thermal anemometry does not allow measurements under these conditions. When making measurements with a LDV in air, it is necessary to seed the flow with particles. Seeding is a challenge in applying these measurement techniques to flows in boundary-layer wind tunnels. Efforts to understand the basic mechanisms affecting pressure fluctuations and associated extreme pressures on a bluff body will be advanced by the ability to measure the flow in separated shear layers and within separated regions associated with these shear layers. The use of a LDV system provides an additional tool to explore this complex region.