Numerical Simulation Of Thermal Environment In Urban Residential District

Numerical simulation of thermal environment in an urban residential district is a heated and challenged topic home and abroad in recent years. This dissertation analyzes and studies mainly the basic theories and applications of CFD (Computational Fluid Dynamics) and NHT (Numerical Heat Transfer).Governing equations of outdoor turbulent airflows have been set up and improved, considering the impact of temperature differences, which induces the standard K-e turbulent model insufficient.An effective discritized scheme based on staggered grids is provided by deeply studying the construction and implementation of difference scheme on non-uniform and staggered grids. Coupling of velocity and pressure is solved by SIMPLE method; the boundary conditions and relations of velocity and pressure are analyzed in details. Several algorithms of algebraic equations are listed, and Successive Linear Under Relaxation (SLUR) is expatiated and analyzed carefully.Several ways of coupling of solid-fluid regions, including that vacant proportion practice, segregated volume practice etc, are discussed, and the brief treatment method of solid-region in the fluid is put forward.Post-processing techniques are expounded and discussed from the basic theories and applications of commercial software. Then visualization of heat and mass transfer is put into practice.Numerical simulation and analysis of wind environment in an urban residential district are carried out, based on the theoretical research conclusions mentioned above. Airflow fields distributions of pressure and turbulent quantities are obtained and laid out. Statuses of wind environment with two different inflowing-azimuths are discussed.The testing of thermal environment in one urban residential district of Changsha City in Sep, 2002 is retrospected and concluded. Variations of surface temperatures of the buildings various terries, urban streets in that day are discussed, inflow boundary conditions and partial thermal boundary conditions for thermal environment simulation are obtained. The thermal environment status in this region could be macro-discerned.Several feasible boundary conditions of thermal environment computations are provided. Numerical simulation of thermal environment in that residential district is carried out depending on theoretical studies, wind environment simulations and thermal environment testing mentioned above. Distributions of wind velocity, pressure, turbulence and temperature in two different periods are investigated and analyzed, and feasibility of thermal environment numerical simulation is proved by comparison of temperature and velocity values between testing and simulation in some tested spots.