A laboratory study on the sandy ripples' processes and effects on the wave field due to the water wave action

• Main Authors: Chang, Kuo-Ching, 陳國欽
• Other Authors: Lin I-Chen
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/22869789889034458620

碩士 === 淡江大學 === 水資源及環境工程學系 === 86 === In the aspect of engineering application,the existence of the ripples will affect the on-offshore sediment transporting direction . The ripples may also be one of the major factors of which may affect the quality of sediment transportation.In this study, the flow visualization technique is utilized to obtain an elementary knowledge about the transient processes until mature sandy ripples being formed.The mature wavelength and wave height of ripples are ripples being formed. The mature wavelength and waveheight of ripples are also made by using a/D50 and Shields parameter φ. The experimental relationships between the ripple geometry and hydraulic parameters were derived. The effects due to the existence of the ripples on the changes of wave heights are also studied in order to estimate the related friction factor . In which functional relationships between the ripple geometry and hydraulic parameters were derived as fw=1.5468(η^2/a*λ)^0.64 . The results of moving bed experiments are smallthan the former results of fixed artificial rippled shear plate . The form roughness can be calculated from Swart's formula (1976) , and Ks is about 0.9~2.7 η. The experimental results reveal that the relation between the equivalent form roughness Ks/ηand Shields parameter φ is Ks/η=7.8φ^0.837 .