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~ '. .. 740 HYDRAULIC ENGINEERING '94 this flow pattern is only part of Ibe picture, inslead Ibe fronl bydraulic jump ;, accompanied by two side bydraulic jumps (figure 2c & 3c), The nexl two flow patterns are nol covered by the theory. the first is the occurrence of hydraulic jumps bolb on Ibe leading and lrailing edge of the boulder (figure 2d) , The next occurs witt, Ibe stage gets bigh enougb lhat the fronl bydraulic jump gets wasbed oUlleaving just the bydraulic jump attacbed 10 Ibe rear edge of the boulder (figure 2e), When tilt boulder becomes submerged Ibe theory describes a waler surface with a dip as it flows over Ibe boulder, bullbis was never seen in tbe fleld (figure 3d), The Ibeory's ne" patlern is when Ibe bydraulic jump can appearabove or bebind Ibe boulder (figure 3e), In the field it is always behind and is no longer attached to the boulder, but as now increases il moves downstream (figure 20, The final flow pattern in Ibe theory is one of only a slight rise in the water surface as the water flows over the boulder (figure 30, This is the possible seventh flow pattern lhat was only really documenled in the field once, althougb if was seen several times when tbe flow was very bigb. 2.0 I.g ~ 1.6 u "" ~ 1.4 . -3 1.2 e 1.0 ... I O.s 1;; 0.6 .!l . ::'l1 0.4 0.2 Wave f, lySupe critical ow(= 0) I I Pattern FieldObservations (-LD) OLD OS l>.f&S x f&B ",B OD +00 IH~~ ;.. ~ nlor'" k bydn plicjun (-B) l~f '" . 0 ~ . + u ,,~. '.. 08 o 0 " Hydrau X v' ,v Jumo f Iy Subc 'ticalfl w 0.0 0.0 0.5 1.5 1.0 2.0 2.5 3.0 3.5 4.0 R.elative 8ubIBeqcnce figure 2. Batburst et aI., (1979) flow pattern theory verses field observations, Conclusion There are six, or possibly seven flow patterns that describe the genemtion and location oftbe bydraulicjumps and can be seen clearly in figure I, The field data first reveal that their appeared to be no relation with the mainstream Froude number. This is perhaps unexpected, bot if can be interpreted that tbe relationsbip was masked by tbe affect of more important variables, rather than not being there at all. The second most noticeable finding is thai the field data has a narrow range compared to the ext~t of - . , fLOW PATIERNS--STREAM . d oes these now pattern changes in a very the theOry. It appears .that the over un e~~ Froude number values. The range of narrow range of relative sub.m~rgenc: 7 t I 0 wbile the theory recognises tbat a rtlative submergenc~ :-~es 1~ n:.r::.e ~Iu~ ~d were too low, 0.5 to 0.8. The fun narrower range woul lInpo be n I . used in the theory while the river bas a exlent of possible Froude num r.~ u:1:ive submergence of2.0. The third finding narrow range of 0.2 to 0.9, even W1 a bands in a plot of relative submergence is that the flow patterns ~era:~y:,:~ ~~:in the bands, especially t!'e flow pattern verse' Froude number, ere, (FS) and a downstream bydrauhCJump (D), Even with front and side bydraulic,JUrnps , . " ed and a good trend is apparent, The '0, for field da,:, tbis sbC4ydtter It- s~rpns~~~lf.J:::t~nd bebind tbe boulder (f!3)' "!Id th,e now psllern WIth tbe ~ IC J:dP bydraulic jump (B), seem to be reslncted I~ tbeu next in the sequence, the tra:'~ ~. narrow nature suggests that these particular occurrence to very narrow s. et~ others existing for a restricted range of now patterns are more uns~e ~an t ~t rns th~ show the front and side hydraulic relalivesubmergencevalues. e :~:'I~ jump (D) have a much wider range of jumps (FS), and the downstream ~ can occu; making them more persistent ftlativesubmergencevaluesover~lC:: th:row bands'may be viewed as transitional now patterns. The patterns shOWlRg ten ition from a more stable pattern to the now patterns whh~' . "able the wd artatek to ~W:e the first author was a NERC student. next. The work rep' ,:cd was un e en O.s s dII< s 4 d)~ df\ J sub e) 0.3 s fr s I Hyd?1ulic - ~p -'~' f\ sub super sub o fr" I --- dII< s 0.5 a) fr s 0.5 Flow, separation ~ake sub b) 0.5 s fr s I Hydraulic Flow jump .epara~ _ ~~... sub super sub c) Fr" 1.2 Flow ~;:~raUllC separation ~ W'. super su ake fisore 3' Representalion of Batburst et ai" (1979) now pattern supcritical now, super"" supercritical flow). (\ super tbeory (sub .. References 'D B (1979), "Hydraulics of mountain Bathurst, J. C., Li, R. ~.! andgiSlm~ns, E~~eering Research Center, Colorado rivers," Department of eml ~~I :; n~ER78_79JeB-RML-DBS55, 229p, Slate University, Fort Cotins, '-"U 0 0, i .