The effects of roadside trees on outdoor thermal environment and air quality within the street canyons in the central part of Sendai city were numerically investigated by CFD analyses coupled with calculations of radiation and conduction. Several cases of analyses were carried out to clarity the effects of tree arrangement, density of trees, elevations and shapes of tree crowns. Five equations: (a) transport equation of momentum, (b) transport equation of heat, (c) transport equation of moisture, (d) transport equation of contaminant gas and (e) heat transfer equation by radiation were solved. The tree canopy model optimized by the present authors was used to reproduce the aerodynamic and thermal effects of trees. The situation where trees were not planted was also simulated for comparison. The results showed very complex effects of roadside trees.
