Flow over periodic hills: an experimental study |
| |
Authors: | Ch Rapp M Manhart |
| |
Institution: | 1.Fachgebiet Hydromechanik,Technische Universit?t München,München,Germany |
| |
Abstract: | Two-dimensional flow over periodically arranged hills was investigated experimentally in a water channel. Two-dimensional
particle image velocimetry (PIV) and one-dimensional laser Doppler anemometry (LDA) measurements were undertaken at four Reynolds
numbers (
\text5,600 £ Re £ \text37,000\text{5,600} \le Re \le \text{37,000}). Two-dimensional PIV field measurements were thoroughly validated by means of point-by-point 1D LDA measurements at certain
positions of the flow. A detailed study of the periodicity and the homogeneity was undertaken, which demonstrates that the
flow can be regarded as two-dimensional and periodic for
Re 3 \text10,000Re \ge \text{10,000}. We found a decreasing reattachment length with increasing Reynolds number. This is connected to a higher momentum in the
near-wall zone close to flow separation which comes from the velocity speed up above the obstacle. This leads to a velocity
overshoot directly above the hill crest which increases with Reynolds number as the inner layer depth decreases. The flow
speed up above that layer is independent of the Reynolds number which supports the assumption of inviscid flow disturbance
in the outer layer usually made in asymptotic theory for flow over small hills. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|