Study on street canyon flows with bottom heating

Urban street canyon flows in the presence of bottom heating are investigated using a two-dimensional numerical model with a k-e turbulence model. The simulations show that when the wind speed is slow the bottom heating can have important effects on the flow regime, an upward buoyancy flux created a distinctive effect on the mail flow, thereby dividing the flow structure into two contra-rotating cells. As the result, the higher concentration may appear on the windward face than on the leeward face. On the contrary, when the wind speed is high or there is no heating, there is a unique vortex in the street canyon, the higher concentration may appear on the leeward face than on the windward face. It is concluded that the temperature different range and the wind speed are same important for the thermal effects in street canyon.