Abstract
Complex heat transfer fluxes occur in the urban canopy layer on typical summer days. It is important to clarify the heat and momentum flux on the urban surfaces. The experiment was performed in the thermally stratified wind tunnel in Tokyo Polytechnics University. Experiment was conducted on 8 cases of unstable flow. Bulk Richardson number was –0.268(US1) to -0.02(US4) on smooth surface and –0.262(UR1) to –0.024(UR4) on rough surface. To measure flow temperature, cold-wire was used. Wind velocity distribution was measured by using 2-D LDA. Thickness of turbulent boundary layer is 0.1m to 0.25m on smooth and rough surface. Thickness of thermally boundary layer is same as turbulent boundary layer. The value of momentum flux is increase with the decrease of stability. Vertical heart fluxes of near the surface indicate positive value. It shows create turbulence by buoyancy. The value of vertical heart fluxes on rough surface larger than on smooth surface.
