Forced hydraulic jump on artificially roughened beds

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In the scope of the study, prismatic roughness elements with different longitudinal
spacing and arrangements have been tested in a rectangular flume in order to reveal
their effects on fundamental characteristics of a hydraulic jump. Two basic
roughness types with altering arrangements have been tested. Roughness elements of
the first type extends through the channel width against the flow with varying length
and pitch ratios for different arrangements. The second type is of staggered essence
and produced by piecing the roughness elements defined in the initial type into three
parts which are equal in length. The doublet formed from the pieces on the sides is
shifted to the consequent row to make two successive roughness rows encapsulate
the channel span completely. Staggered roughness type is formed with the repetition
of this arrangement along the flume. Independent of their type and arrangement, the
entirety of roughness elements are embedded in the channel bed in order to avoid
their protuberance into the flow, based on the presumption that the crests of the
roughness elements levelled with the channel inlet would be less exposed to caving
effects of flow than the protruding elements.

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In the study, influence of the proposed roughness elements on the fundamental
engineering concerns as the length, height (tail water depth) and energy dissipation
capacity of hydraulic jumps has been questioned in the light of empirical work and
related literature on forced and smooth hydraulic jumps.
At the final stage of the study, it was concluded that both strip and staggered
roughness have positive effects on the characteristics of hydraulic jump given above.
3-7% more energy dissipation was observed in jumps on rough beds compared to
classical hydraulic jumps. For tailwater dept reduction, whereas strip roughness
provided 5-13%, staggered roughness led to 7-15% tailwater depth reduction
compared to classical hydraulic jump. While strip roughness reduced jump length
around 40%, 35-55% reduction was observed with staggered roughness when
compared to classical hydraulic jump.

Çağdaş Şimşek
Forced hydraulic jump on artificially roughened beds · 2006 · 105 sayfa.
Danışman: Doç.Dr. Nuray Tokyay
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