On the simulation of flow around discrete coniferous trees

The present study is to establish a numerical model capable of predicting flow past discrete coniferous trees, so as to provide a handy tool for pedestrian wind analysis during the preliminary design stage for local wind environments. In the study, a tree factor was proposed to reflect the effect due to the existence of the trees. Besides the applications of numerical computations in flow analysis, wind tunnel measurements were also performed to guide and confirm the numerical simulations. By comparing the velocity profiles at certain downstream cross-sections of tree panels, the variation of the tree factor was calibrated and the result can be readily used to predict the flow around discrete coniferous trees. Results also showed that the proposed tree factor generally increased with increases in the volume ratio and horizontal thickness of the tree body. Based on the calibrated relationship of the tree factor, finally, additional numerical computations were performed to simulate flow past an isolated tree and dual trees in a tandem and a side-by-side arrangement. The predicted downstream wind velocity profiles appeared in good agreement with the measurement results.