Numerical study of wind profiles over simplified water waves

Shuyang Cao , Enzhen Zhang , Liming Sun , Jinxin Cao

Abstract

Vertical profiles of mean and fluctuating wind velocities over water waves were studied, by performing Large-Eddy Simulations (LES) on a fully developed turbulent boundary layer over simplified water waves. The water waves were simplified to two-dimensional, periodic and non-evolving. Different wave steepness defined by a/y (a: wave amplitude; y : wavelength) and wave age defined by c/U (c: phase velocity of the wave; U: bulk velocity of the air) were considered, in order to elaborate the characteristics of mean and fluctuating wind profiles. Results shows that, compared to a static wave, a moving wave plays a lesser aerodynamic role as roughness as it moves downstream slower or a little faster than air, and plays more aerodynamic roles when it moves downstream much faster than air or moves in the opposite direction to air. The changes of gradient height, power law index, roughness length and friction velocity with wave age and wave amplitude are presented, which shed light on the wind characteristics over real sea surfaces for wind engineering applications.

Key Words

large-eddy simulation; wave age; wave amplitude; wind profiles

Address

Shuyang Cao and Jinxin Cao — State Key Lab for Disaster Reduction in Civil Engineering, Tongji University, Siping Road 1239, Shanghai, China
Enzhen Zhang — School of Civil Engineering, Tongji University, Siping Road 1239, Shanghai, China
Liming Sun — Tongji Architectural Design (Group) Co. Ltd, Siping Road 1230, Shanghai, China

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