NUMERICAL STUDY OF TURBULENT FLOW FIELDS OVER FLAT AND HILLY TERRAIN CONSIDERING THE EFFECT OF CORIOLIS FORCE

Abstract

In this study, a formula for the maximum turbulence length scale 𝑙􀯠􀯔􀯫 is first proposed to reproduce the neutrally stratified atmospheric boundary layer over different terrain types considering the effects of Coriolis force. The effects of Coriolis force on turbulent flows over 3-D hills with different slopes and height ratios (hill height / atmospheric boundary layer height) are subsequently clarified in terms of flow patterns and turbulent statistics. The results show that the vertical distributions of mean velocity on the windward side of 3-D hills are slightly affected by the Coriolis force regardless of hill slopes and height ratios. However, it is found that the Coriolis force has a positive influence on the wake recovery of 3-D steep hills with large height ratios and its influence enhances as the hill slope and the height ratio increase. Moreover, the fractional speed-up ratio at the crest of 3-D hills is significantly increased as the hill slope and the height ratio increase.