Laser Doppler velocimeter measurements of flow field around a bluff body

Greater understanding of the details of the how fields around bluff bodies and the separated regions associated with these hows is necessary to advanc e the knowledge of fluid-structure interactions. These mechanisms are parti cularly important in wind engineering in determining design pressures on st ructures. In almost all instances the maximum design pressure occurs in reg ions of separated flow. The details of the how in these separated regions a nd the criteria for physical or numerical modeling of the flows in these re gions are not well understood. Measurements have been conducted using a las er Doppler velocimeter (LDV) to examine the structure of separated shear la yers and the associated regions of separated flow. a LDV is an important to ol for this application. A LDV system is capable of measuring reversing flo ws and consequently high local turbulent intensities. Thermal anemometry do es not allow measurements under these conditions. When making measurements with a LDV in air, it is necessary to seed the how with particles. Seeding is a challenge in applying these measurement techniques to flows in boundar y-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 a nd within separated regions associated with these shear layers. The use of a LDV system provides an additional tool to explore this complex region. (C ) 1998 Elsevier Science Ltd. All rights reserved.