A Numerical Study for Turbulent Flow and Thermal Influence over Inhomogenous Canopy of Roughness Elements |
| |
Authors: | Email author" target="_blank">Zhengtong?XieEmail author Jiachun?Li |
| |
Institution: | (1) School of Engineering Sciences, University of Southampton, Southampton, SO17 1BJ UK;(2) Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100080, China |
| |
Abstract: | A large-eddy simulation with transitional structure function(TSF) subgrid model we previously proposed was performed to investigate
the turbulent flow with thermal influence over an inhomogeneous canopy, which was represented as alternative large and small
roughness elements. The aerodynamic and thermodynamic effects of the presence of a layer of large roughness elements were
modelled by adding a drag term to the three-dimensional Navier–Stokes equations and a heat source/sink term to the scalar
equation, respectively. The layer of small roughness elements was simply treated using the method as described in paper (Moeng
1984, J. Atmos Sci. 41, 2052–2062) for homogeneous rough surface. The horizontally averaged statistics such as mean vertical profiles of wind velocity,
air temperature, et al., are in reasonable agreement with Gao et al.(1989, Boundary layer meteorol. 47, 349–377) field observation (homogeneous canopy). Not surprisingly, the calculated instantaneous velocity and temperature
fields show that the roughness elements considerably changed the turbulent structure within the canopy. The adjustment of
the mean vertical profiles of velocity and temperature was studied, which was found qualitatively comparable with Belcher
et al. (2003, J Fluid Mech. 488, 369–398)’s theoretical results. The urban heat island(UHI) was investigated imposing heat source in the region of large
roughness elements. An elevated inversion layer, a phenomenon often observed in the urban area (Sang et al., J Wind Eng. Ind. Aesodyn. 87, 243–258)’s was successfully simulated above the canopy. The cool island(CI) was also investigated imposing heat sink to
simply model the evaporation of plant canopy. An inversion layer was found very stable and robust within the canopy. |
| |
Keywords: | canopy cool island inhomogeneous large-eddy simulation roughness element urban heat island |
本文献已被 SpringerLink 等数据库收录! |
|