Effect of width-to-depth ratio on the mean flow velocities for a Kinoshita meander bend

width-to-depth;Kinoshita;meander;secondary flow

Fernandez, Roberto ; Garcia ; Marcelo H.

关键词: width-to-depth;    Kinoshita;    meander;    secondary flow;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/31050/FernandezArrieta_Roberto.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The present work analyses the effect of different width-to-depth ratios on themean surface velocities of a Kinoshita meander bend. The characteristicsof flow in such a bend have been studied by Ancalle (2007) and Abad andGarcia (2009a) for width-to-depth ratios equal to 2.4 and 4.0. The presentstudy extends that work and includes a higher width-to-depth ratio (equalto 12.0) in addition to those already studied.The main difference between previous studies and the current one is the techniqueused to measure. Particle Tracking Velocimetry (PTV), a non-intrusivetechnique, was adopted here to take the measurements. The technique allowsmeasuring in the Kinoshita flume for higher width-to-depth ratios than it isfeasible with the use of other techniques such as Acoustic Doppler Velocimeters(ADVs).The results obtained from the measurements are also used to validate a2D depth-averaged rigid-lid model called STREMR (Bernard (1993)). Themodel has an empirical correction for secondary flow which is evaluated inlight of the values obtained from the measurements. Results obtained withthe model are in good agreement with the measurements taken, showing thatSTREMR is an adequate tool to model flows in bends even if they are notshallow.Measured and modeled values indicate that different width-to-depth ratioshave similar patterns but the secondary flow intensity is different in all ofthem, thus modifying the time required for the core of high velocities to migratefrom the inner part of the bend to the outer part. Velocity turnover inregions of low curvature happens at slightly different locations for the differentwidth-to-depth ratios suggesting that the secondary flow intensity plays a role in it.