Turbulence within and above real and artificial urban canopies

摘要: Understanding the turbulence characteristics of ASL flow in and through urban areas is essential to predicting dispersion cities. Urban areas, however, alter inherent found Atmospheric Surface Layer (ASL) a variety mechanisms. Due difficulty obtaining characteristic measurements actual simplified models (usually wind tunnel models) are typically used isolate mechanisms affecting around buildings or groups buildings. Results from these often validate computational models. These turn predict that have complex geometries topography based on limited amount data area. The depth much larger than most making it possible consider as surface roughness at large scales. At scales area therefore produces regime above an (in inertial sublayer above) basically has been modified by presence terrain below it. It can be argued transitions more » bluff body influenced upstream conditions surrounding Roughness Sublayer (URSL) into Canopy (UC). In regimes rational expect (i.e. wake recirculation regions, vortex shedding, etc.) impose affect transfer energy between eddies different sizes. Thus detailed understanding phenomena is, for example, necessary accurately high-resolution This paper compares sonic anemometer obtained during Joint 2003 (JU03) Field Experiment with those simulated Mock Setting Test (MUST). JU03 was held downtown Oklahoma City street canyon, while MUST performed array aligned, same-size obstacles simulating near full scale. experiments, both true ASL, provide opportunity compare produced canyon semi-complex geometry highly geometry. Local effects were dominate lowest 10% producing predominantly positive along-wind vertical cospecta variations mean statistics. A complicated structure velocity components. also dramatically cascade some cases adding over discrete bandwidths altering slope spectra high frequency range typical f{sup -5/3} behavior subrange. « less