EFFECT OF FLOW IRREGULARITY ON OSCILLATORY BOUNDARY LAYER FLOW

Proceedings of the International Conference on Coastal Engineering

Mahesa Bhawanin¹  Jan S. Ribberink²  Dominic A van der A¹  Tom O'Donoghue¹ 

[1] University of Aberdeen;University of Twente

关键词: oscillatory flow;    boundary layer;    turbulence;    flow tunnel;    laboratory experiments;   

DOI  :  10.9753/icce.v34.sediment.44

学科分类：建筑学

来源: Coastal Engineering Research Council

【 摘 要 】

The paper reports on new oscillatory flow tunnel experiments in which detailed measurements have been made of boundary layer velocities for full-scale regular and irregular oscillatory flows over sand-rough and gravel-rough fixed beds. The irregular flows were generated by amplitude modulation of the corresponding regular flows, to give same free-stream urms and same velocity and acceleration skewness. The experimental setup is described and initial results relating to flow structure, turbulence and bed shear stress are presented. Results presented for boundary layer development, turbulence intensity, turbulent stress and log-law-based estimates of bed shear stress suggest that the hydrodynamics within a flow half-cycle are largely independent of the previous flow half-cycle, at least close to the bed where the presented results have focused. Time-history effects are not entirely absent however, especially higher up from the bed. More detailed analysis is needed to elucidate further.

【 授权许可】

Unknown