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their positions were video-recorded. The recorder was left to play for the duration of the experiment, in which time at least 200 trajectories were recorded. These video records were analysed manually to give two data sets. The first set concerned the trajectories of individual particles; they were grouped into seven primary modes as described in chapter 3. Also, the point at which the particle was deposited on the downstream lee or stoss slope was recorded along with the duration of the particle trajectory from the crest to this landing site. Such distributions are presented in chapter 3 for varying values of depth-averaged flow speed and particle quiescent fall speed. The second set concerned each particle's contribution to the notional concentration beyond the crest during its flight. The description of the methods used here are detailed in chapter 3. 4.4 Chapter 4 experimental methods (Lee and stoss slope capture) The bedforms were arranged as for the jetting experiments except that an initial test was carried out with only two bedforms. All subsequent tests used three bedforms as above. A detailed account of the experimental methods are given in chapter 4. 5 CONCLUSIONS A 6.7m long flume designed for the study of the flow and particle trajectories over sandwaves was constructed and found to give an 2-15
even flow over 0.45m width and up to 0.45m depth. The flume has been used successfully to study the flow over fixed bedforms, from which a number of points concerning adaptions and improvements have been made. 6 SUGGESTED EQUIPMENT MODIFICATIONS Improvements to the rig are listed below in order of priority. - Fitting a stainless steel pump to prevent water discolouration. - Construction of a larger suction tank with sieve or a settling compartment for batchwise removal of the experimental particles. - Additional flow discharge metering equipment. A simple venturi or orifice plate in the discharge line should suffice. - Permanent fitting of depth measurement point gauges. - Increase of flume length should space become available. This would not be too costly since the flume section is built in component form and can be added to as desired. - Providing a pumped drainage system for cleaning and flushing. Re-engineering to allow the flume to be tilted. This would probably involve a complete re-build since a tubular supporting beam is considered most suitable for such purposes. 7 ACKNOWLEDGEMENTS Thanks are extended to Stan Ward for his diligent effort in undertaking such a mammoth construction task alone, for producing such robust equipment from less-than-ideal material and drawings, and for generating so many good ideas. Thanks also go to John 2-16
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FLUID-PARTICLE TRANSPORT DYNAMICS O
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SYNOPSIS The local dynamics of sand
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TABLE OF CONTENTS LIST OF FIGURES C
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CHAPTER 3: JETTING EXPERIMENTS Summ
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2 Numerical scheme 6-5 3 Results 6-
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LIST OF FIGURES Chapter 1 Figure 1.
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U=830mm/s. Figure 16. Thomas et al
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in the boundary layer. a) The forma
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Chapter 3 Figure 1. After Alien (19
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at various values of U/V from 2.7 t
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y Coanda-flapping of the free shear
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of a sandwave crest in the estuary
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Figure 7h-i. The temporal fluctuati
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inclined downwards whereas the time
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starting position (X,Y) at zero ini
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d Sand grain diameter (m) Fi Number
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G Vortex core growth rate (tn/s) ki
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1 INTRODUCTION Sand forms the botto
Page 37 and 38: where U is the depth-averaged veloc
Page 39 and 40: The wavelengths of dunes primarily
Page 41 and 42: detached and then confined within a
Page 43 and 44: The vortex radius rn and apparent w
Page 45 and 46: Recent work by Nezu & Nakagawa (199
Page 47 and 48: found in the outer streaks. 4 MODEL
Page 49 and 50: (1987), for example, modelled gas-s
Page 51 and 52: Profiles of shear stress and turbul
Page 53 and 54: 6ft v "' ' Re In the limit of large
Page 55 and 56: that the particle radius was much s
Page 57 and 58: and travels downstream at speed }*U
Page 59 and 60: capture by transient large eddies s
Page 61 and 62: Chapter 1 Figure 3. Alien (1984). L
Page 63 and 64: Chapter 1 10 8 e 4 I 08 •- 02 Yal
Page 65 and 66: Chapter 1 bw speed fluid Figure 11.
Page 67 and 68: Chapter 1 Figure 16. Thomas et al (
Page 69 and 70: Chapter 1 StCMl STRESS SCALE « K /
Page 71 and 72: Chapter 1 Haiht Vdodty Figure 22. S
Page 73 and 74: Chapter 1 Time = 1.2 2.4 ' ' :•
Page 75 and 76: 1 INTRODUCTION AND DESIGN CONSIDERA
Page 77 and 78: Initial costing for a flume of the
Page 79 and 80: flanges and a maximum flow rate of
Page 81 and 82: could be wound above or below the l
Page 83 and 84: 4 EXPERIMENTAL SETUP AND METHODS He
Page 85 and 86: 4.2 Flow visualisation and model pa
Page 87: any divergence from the beam and to
Page 91 and 92: Chapter 2 Opt 1 h(m) 0.01 Max D(m)
Page 93 and 94: Chapter 2 Part of side section Putt
Page 95 and 96: Chapter 2 Suction tank Bypass Disch
Page 97 and 98: Chapter 2 QUncorrectedflow £ Corre
Page 99 and 100: Chapter 2 60 r 501 40? 30r 20 r lOr
Page 101 and 102: 1_ INTRODUCTION The main features o
Page 103 and 104: 2 EXPERIMENTAL METHODS A detailed d
Page 105 and 106: the relationship is then simply ^ -
Page 107 and 108: number about 0.14. They were taken
Page 109 and 110: along the stoss slope. Figures 8 an
Page 111 and 112: 3.3a) Jetting trajectories when U/V
Page 113 and 114: errors increase substantially due t
Page 115 and 116: likely distributions. 4 DISCUSSION
Page 117 and 118: Our suggestion here is akin to that
Page 119 and 120: not accommodate the differing migra
Page 121 and 122: considered by proponents of numeric
Page 123 and 124: Chapter 3 C,;: Figure 3a-j. The pla
Page 125 and 126: Q CO 23 Figure 6. Distribution of p
Page 127 and 128: Chapter 3 X(cm) 1 2 3 4 5 6 7 8 9 1
Page 129 and 130: Chapter 3 U(m/s) V(m/s) U/V M1+M2 M
Page 131 and 132: O I r+ 21 CO 2 5 8 11 14 17 20 23 >
Page 133 and 134: 8 11 14 17 20 23 25 + Position Figu
Page 135 and 136: Chapter 3 U/V= B5.7 Q9.3 BlO.7^12.8
Page 137 and 138: Chapter 3 Band 1 2 3 4 U(m/s) 0.2 0
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1 INTRODUCTION In chapter 3 we cons
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velocity for a maximum of 40% of th
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layer vortices extending over the d
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2.2 Methods for measuring Coanda-fl
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Section 3.4 considers suspension fr
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This same flow structure has also b
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3.2b) Effect of varying inter-crest
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those with fall speed 0.060m/s for
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3.4 Particle capture from stoss slo
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are discussed in the context of est
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jetted grains settling to the lee s
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Chapter 4 ENTRAINED FLOW Figure 1.
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Figure 3a-j. The plates show partic
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Chapter 4 Percentage occurrence •
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Chapter 4 Interval (s) 60 80 100 12
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Chapter 4 0.024m Conc=8% Figure 12.
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Chapter 4 Figure 16. A cloud of par
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1 INTRODUCTION We use a Rankine vor
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effective particle fall speed in th
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particle velocity Vx=0. The initial
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the vortex axis. Vortex circulation
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dimensional fall times T^ for diffe
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horizontal component lift force (fi
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corresponds to the trajectory trave
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stepping the calculation in VT . Do
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averaged exclusion of the coherent
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C from figure 11 (ie 2.2) then we h
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PflRTICLE DENSITY=1000.000 Kg/n3 LI
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Chapter 5 ft) J k I Figure 4. Varyi
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Chapter 5 Relative Fall Time va Sta
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Chapter 5 Figure 7a. Trajectories o
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Chapter 5 Velocity X —Inertia X L
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Chapter 5 Velocity X —Velocity Y
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Chapter 5 Velocity Y Inertia Y Lift
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Chapter 5 DENSITY PARTICLE=2850.000
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Chapter 5 Rad = 0.006 Rad=0.003 Rad
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Chapter 5 H3 Y=0 Oy=i m Y=2 D-y=3
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CHAPTER 6: NUMERICAL SIMULATION OF
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next. If we now adopt the classical
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st = (4) Where p p was the particle
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3 RESULTS 3.1 Specified 6 and V Fig
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the blue squares to double loops an
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A0fl0 = 1.25V-0.33G-0.005 (7) and f
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Conversely, the upper line of the p
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equations. Such a discrete vortex m
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Figure 1. Schematic of the shear la
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Chapter 6 J G H K M Figure 3. Seven
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Chapter 6 1 T V=0.161 0.1 -- V41185
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Chapter 6 - DataV=0.0335, G=0.01
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CHAPTER 7: RECAPITULATION AND RECOM
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were shown to compare well with pre
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We have shown Coanda-flapping makes
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figure 5, was critically dependant
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stoss slope suspension studies of c
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Figure la-g. The seven trajectory m
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Chapter 7
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Chapter 7 0.0351 0.03 " 03 0.025 0.
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Flow 16 (1) pp 19-34. Bernal LP (19
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Mechanics of Sediment Transport. Is
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turbulence near a smooth wall in a
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moderate Reynolds number shear laye
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Spalding (1961). A single formula f
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USA. 1-12
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APPENDIX 1: BOUNDARY LAYER STUDIES
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(1967) used hydrogen bubble visuali
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The burst-sweep dynamics study of U
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Horseshoe vortex Vortex filament Ho
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APPENDIX 2: FAST9003.HR(RW)/NHT - P
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of the vorticity shed into the near
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transport dynamics of multiphase fl
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APPENDIX 3: FUNDAMENTAL NAVIER-STOK
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APPENDIX 4: CLOSURE METHODS 1 ZERO
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where cr k and CD are empirical con
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K = CDe^ 2 p 2 \U2 -U1 \=e 1e 2 c (
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APPENDIX 6: K-e MODEL OF JOHNS ET A
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They then defined a hydrodynamic co
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with respect to the rest of the vor
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The vorticity equation can be split
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around the crest and the motion of
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micrometers, with mean of 80 microm
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i——COMPARISON WITH PREVIOUS WOR
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width speed (metres) ^(cm/s) 11 Fig
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U (33) = 1.16ms-' Depth = 2.65 m Fi
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APPENDIX 9 : DERIVATION OF FORCES O
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APPENDIX 10 : MODEL CODE FOR CALCUL
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APPENDIX 11: MODEL CODE FOR GROWING
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105 if (scancode .eq. 57) stop GOTO
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