EXPERIMENTAL STUDY ON FLOW KINEMATICS AND SEDIMENT TRANSPORT UNDER ORTHOGONAL WAVE-CURRENT INTERACTION M. PRADEEP CHAMINDA FERNANDO NATIONAL UNIVERSITY OF SINGAPORE 2006 EXPERIMENTAL STUDY ON FLOW KINEMATICS AND SEDIMENT TRANSPORT UNDER ORTHOGONAL WAVE-CURRENT INTERACTION M. PRADEEP CHAMINDA FERNANDO (B.Sc.Eng. (Hons.), University of Peradeniya, Sri Lanka) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF CIVIL ENGINEERING NATIONAL UNIVERSITY OF SINGAPORE 2006 Dedicated with love and gratitude to my parents Your hard work and all commitments are for my successes ACKNOWLEDGEMENTS First of all, I offer my heartfelt thanks for my god Jesus Christ for giving me the wisdom, strength and finally directing me to the end to succeed in higher studies. I would like to express my sincere and deepest gratitude to my supervisor, Asst. Prof. John Guo for assisting me in the Ph.D. study. Your valuable advice, suggestions and continuous guidance provided to complete my study are highly appreciated. Also I would be very much grateful to Prof. Cheong Hin Fatt the chairman of my thesis advisory committee and Assoc. Prof. Lin Pengzhi for helping me with all the suggestions and comments to progress with my experimental study. Dr. Wu Yongsheng, thank you for your help during your stay in NUS. Also I must thank Prof. Albert Williams and Todd Morrison for sharing some field data for the study. I am also grateful to the civil engineering department selection committee for giving me an opportunity to study at NUS and also for providing me with financial assistance. Mr. Krishna, Mr. Ooh Sing Hua, Mr. Martin, Mrs. Norela, Mr. Semawi and Mr. Roger thank you very much for your continuous support specially during the setup of experiment. Thanks are extended to hydraulics group friends Dr. Liu, ChuanJiang, DongChao, Zhang Dan, XioHui, Didi, DongMing, WenYu, HaoLiang, QuangHong and others for their support and friendship. I specially grateful to Edgar for being a very good friend for me during my stay at NUS and for all your kind supports. i My deepest gratitude and love to you my parents and all my family members. My parents late Mr. Hamilton Fernando and Mrs. Malani Fernando, I am indebted to you for all your support and endless love. I know that you dedicated your life lot with continuous hard work, emotional commitments and unforgettable sacrifices to educate your children. Dear mother you are the one who made your children’s life success and here, I sincerely memorize everything adoringly. My parents in law late Mr. Joseph Fernando and Mrs. Allen Obris, my sincere gratitude is for you for your kindness, love and support. Father and father in law, I dearly remember, with heartfelt sorrow, your sudden death before completing my studies. My wife Sithara, my deepest thanks to you for supporting me throughout with love, understanding and constant encouragement. My dearest daughter Shamary Duwa, you are the gift from heaven, I thank you my new born for making us very happy. I also remember my elder sister Chanika, brother in law Lakshman Aiya, Hirusha Putha, Hirushi Duwa, younger sister Ashika and Nona Ranjanee for your love and all your support for my studies. Special thanks to my brothers in law Dilak, Demian and Nalaka for care you extended to my parents during my stay in Singapore. I am especially thankful to my wife Sithara and Anu for helping me to correct the thesis. Without your support I would not be able to complete this on time. My Sri Lankan friends Shameen, Dulakshi, Dammika, Dumindu, Buddhi, OG, Lesly, Namunu, Kumara, Lakshan, GC, Prabath, Ravi, Sidanths, Damitha, Predipika, Ananda, Jagath, Nadasiri, Thushara, Indika, Lalith, Herath and others you all made Singapore a home, accept my big thanks for your friendship and support. ii TABLE OF CONTENTS Page i Acknowledgements Table of contents iii Summary vii Nomenclature x List of figures xiv List of tables xix CHAPTER INTRODUCTION 1.1 Wave-current interaction 1.2 Sediment transport 1.3 Objectives 13 1.4 Outline of the thesis 15 CHAPTER REVIEW OF LITERATURE 2.1 Theoretical work on combined wave-current flow 16 2.1.1 Flow kinematics 18 2.1.1.1 Analytical solutions (wave effects on currents) 18 2.1.1.2 Numerical models (wave effects on currents) 22 2.1.1.3 Surface Parameters of combined flow 22 Bed dynamics 24 2.1.2.1 Bed shear stresses and flow regimes 24 2.1.2.2 Ripple geometry and sediment motion 26 2.1.2 2.2 2.3 16 Laboratory Experiments 30 2.2.1 Co-linear wave-current flow experiments 31 2.2.2 Arbitrary angle wave-current flow experiments 33 Field measurements 36 iii 2.4 2.3.1 Non-storm conditions 36 2.3.2 Storm conditions 37 Summary 38 EXPERIMENTAL FACILITY AND INSTRUMENTATIONS 40 3.1 Acoustic Doppler Velocimeter (ADV) 40 3.2 PV-07 Electronic bed profile indicator 42 3.3 KENEK capacitance type wave height meter 45 3.4 Wave generation system 47 3.5 Wave basin carriage 47 3.6 Flow meter, Oscilloscope and WaveBook data acquisition system 48 CHAPTER CHAPTER EXPERIMENTAL SET-UP 4.1 4.2 50 Experimental set-up over fixed and movable beds 50 4.1.1 Generation of currents 53 4.1.2 Wave generation 54 4.1.3 Wave Absorbers and movable bed 56 Validations of experimental set-up and preliminary justifications of flow conditions 57 4.2.1 58 Pure current flow 4.2.1.1 Steady and uniform flow check across the current channel 4.2.2 58 4.2.1.2 Current directional velocity distribution 59 4.2.1.3 Bed shear stress and sediment motion 62 Pure waves 62 4.2.2.1 Wave height distributions in the basin and wave reflection 63 iv 4.2.2.2 Three directional velocities and comparison to linear wave theory 4.2.3 66 Combined wave-current flow 67 4.2.3.1 Cross-wave analysis 68 4.2.3.2 Wave height distribution in the wave-current interaction area 4.3 68 4.2.3.3 Three directional velocities 70 4.2.3.4 Sediment settling in the wave-free zone 72 Experimental procedure 72 4.3.1 Wave-current interaction over the fixed bed 72 4.3.2 Wave-current interaction over the movable bed 73 CHAPTER EXPERIMENTAL RESULTS AND DISCUSSION (CONCRETE BED) 75 5.1 Eddy-viscosity structure of wave-current orthogonal interaction 75 5.2 Water surface parameters of orthogonal wave-current flow 83 CHAPTER BED GEOMETRY AND SEDIMENT TRANSPORT 6.1 (MOVABLE BED EXPERIMENT) 88 Pure wave flow 88 6.1.1 Vortex Ripples’ Geometry 92 6.1.2 Effective bed roughness scale ripples formed by pure waves 98 6.2 Combined wave-current flow 103 6.3 Sediment transport under wave-current orthogonal motion 109 v CHAPTER WAVE EFFECTS ON CURRENTS (MOVABLE BED EXPERIMENT) 112 7.1 Pure current over plane sand bed 112 7.2 Pure current over ripples formed by combined wave-current flow 116 7.3 Combined wave-current flow over the movable bed 118 7.3.1 Current directional velocity distribution 122 7.3.2 Bed shear stress and hydraulic roughness height 128 7.3.3 Comparison of experimental measurements with existing theoretical models and suggestions to modify the models 131 7.3.3.1 Christoffersen and Jonsson (1985), Fredsǿe (1984) models 7.3.3.2 Grant and Madsen (1986) model 132 139 CHAPTER AN ANALYTICAL SOLUTION ON WAVE-CURRENT FLOW AT AN ARBITRARY ANGLE 145 8.1 Introduction on past wave-current models 145 8.2 Bed shear stress under combined wave-current action 151 8.3 Calculation procedure 161 CHAPTER VALIDATION OF THE PRESENT MODEL 9.1 9.2 Model predictions in comparison to the field measurements 164 164 9.1.1 Drake et al. (1992) (Northern California shelf) 164 9.1.2 Huntley and Hazen (1988) (Nova Scotia shelf, Canada) 168 9.1.3 Cacchione et al. (1987) (Russian river shelf) 171 9.1.4 Grant et al. (1984) (Northern California shelf) 173 9.1.5 Larsen et al. (1981) (Washington, Australian shelf) 175 Model predictions in comparison to the laboratory measurements 179 vi 9.2.1 Present experiment ( φ = 900 ) 9.2.2 Kemp and Simons (1982, 1983), Bakker and van Doorn 9.2.3 179 (1978) ( φ = 00 , 1800 ) 186 Sleath (1990) ( φ = 900 ) 190 193 CHAPTER 10 CONCLUSIONS AND RECOMMENDATIONS 10.1 Experimental set-up 193 10.2 Effects of waves on pure currents 194 10.3 Effects of current on pure waves 195 10.4 Validation and modification of theoretical models 196 10.5 Present theory 199 10.6 Bed ripple geometry and sediment transport 201 10.7 Limitations and suggestions for future work 202 References 205 Appendix A Wave Reflection and Cross-Wave Analysis 221 Appendix B Suspended Sediment Motion in the Wave Free Zone 227 Appendix C Estimation of Nikuradse’s Equivalent Sand Roughness and Determination of Flow Regimes 229 Appendix D Estimation of Critical Depth Averaged Velocity to Produce Non-Eroded Sand Bed 231 Appendix E Sieve Analysis of Sediment Appendix F MATLAB Program for Present Model for a Reference 233 Current 235 Appendix H Wave Height Distribution in the Combined Wave - Current Flow 236 Appendix I Measurements of Current Directional Mean Velocity Distribution in Pure Current and Combined Wave-Current Flows List of publications 239 254 vii APPENDIX I Measurements of Current Directional Mean Velocity Distribution in Pure Current and Combined Wave-Current Flows I.1 Pure current over plane sand bed I.1.1 10.5cm/s depth averaged current Position A u z ( cm ) 0.84 2.43 3.95 5.55 7.10 8.43 10.06 11.33 12.71 14.25 17.20 20.20 23.09 26.06 29.01 Position B ( cm 7.55 8.41 8.88 9.23 9.97 10.10 10.22 10.47 10.51 10.52 10.94 11.25 11.77 11.66 11.73 Position D z ( cm ) 0.96 2.58 4.18 5.65 7.30 8.70 10.55 12.00 13.40 14.96 18.06 20.81 23.90 26.87 29.76 u z s) ( cm ) 1.05 2.66 4.18 5.93 7.20 9.00 10.13 11.57 13.10 14.56 17.60 20.52 23.40 26.45 29.35 Position C ( cm z s) 7.77 9.08 9.40 9.42 9.75 9.98 10.13 10.37 10.54 10.97 11.08 11.20 11.37 11.59 11.51 ( cm ) 0.86 2.40 3.97 5.57 7.30 8.80 10.65 11.37 13.05 14.34 17.30 20.23 23.19 26.20 29.06 u ( cm s) 7.83 8.68 9.01 9.45 9.77 9.99 10.51 10.74 10.52 10.71 10.94 11.02 11.35 12.00 12.38 Position E u ( cm z s) 8.29 9.38 9.75 9.79 10.27 10.49 10.70 11.01 10.89 11.13 11.34 11.59 11.68 11.83 12.05 ( cm ) 1.05 2.68 4.30 5.85 7.34 8.65 9.96 11.62 13.01 14.52 17.46 20.51 23.50 26.44 28.43 u ( cm s) 8.13 8.65 9.60 9.57 9.85 9.38 9.68 10.26 10.74 10.90 11.23 11.24 11.75 11.83 11.90 Stations A, B, C, D, E are shown in Figure 6.1 ( z ) was measured from local bottom 239 I.1.2 13.5cm/s depth averaged current Position A z ( cm ) 0.80 2.40 3.95 5.47 6.81 8.40 9.76 11.27 12.67 14.24 17.23 20.17 23.12 26.10 29.07 Position B u ( cm z s) 9.79 11.03 11.86 11.30 11.99 12.52 12.67 12.76 13.41 13.68 13.85 13.83 14.13 14.75 15.21 ( cm ) 1.11 2.72 4.30 5.91 7.27 8.63 10.15 11.54 12.97 14.53 17.45 20.46 23.41 26.37 29.40 Position C u ( cm z s) 10.30 10.70 11.26 12.17 12.24 12.69 12.56 13.18 13.46 13.45 13.94 13.64 14.50 14.52 15.23 Position D u z ( cm ) ( cm s ) Position E u z ( cm ) ( cm s ) 1.00 2.61 4.13 5.67 7.45 8.61 10.10 11.48 12.97 14.50 17.45 20.47 23.42 26.43 29.35 1.07 2.03 3.77 5.32 7.12 8.61 9.98 11.00 12.42 13.99 17.03 19.97 22.96 25.93 28.90 10.75 12.08 12.75 12.87 12.94 13.70 13.82 14.06 14.03 14.24 14.23 14.45 14.50 15.16 15.82 ( cm ) 0.84 2.44 4.05 5.54 7.15 8.40 9.85 11.30 12.70 14.18 17.30 20.20 23.11 26.00 29.00 u ( cm s) 10.24 11.39 12.11 12.34 12.62 12.79 13.44 13.39 13.90 13.75 14.16 14.48 14.50 14.95 15.73 10.54 10.61 11.54 11.63 12.41 12.52 12.79 12.77 13.19 13.39 14.29 14.87 14.97 15.39 15.77 Stations A, B, C, D, E are shown in Figure 6.1 ( z ) was measured from local bottom 240 I.2 Pure current (depth averaged 10.5cm/s) over the pure wave formed ripples I.2.1 ( H = 9.92cm, T = 1.5s ) Position A (trough closets) u z ( cm ) ( cm s ) 1.35 2.91 4.32 5.85 7.35 8.80 10.63 12.16 13.49 14.87 17.93 20.95 23.85 26.87 29.78 7.26 8.03 8.57 8.90 9.92 10.06 10.50 10.67 10.56 10.90 10.86 11.39 11.56 11.26 12.23 Position D (trough closets) z ( cm ) 1.05 2.65 4.08 5.72 7.33 8.55 10.26 11.50 13.00 14.47 17.40 20.33 23.37 26.25 29.25 u ( cm Position B (crest closets) u z ( cm ) ( cm s ) 1.42 3.06 4.45 5.93 7.53 8.84 10.28 11.77 13.30 14.73 17.42 20.34 23.00 25.80 29.02 6.38 7.58 8.36 9.07 9.11 9.73 9.73 10.01 10.15 10.44 11.02 11.16 11.28 11.63 12.08 1.05 2.36 4.20 5.67 7.06 8.55 9.92 11.52 12.91 14.90 17.40 20.41 23.38 26.41 29.30 7.39 8.24 8.68 9.73 9.50 10.12 10.33 10.51 10.47 10.46 11.02 11.49 11.54 11.51 11.63 Position E (trough closets) z s) 7.22 7.88 8.53 8.73 9.26 9.51 10.14 9.98 10.54 9.88 11.22 10.80 10.96 11.39 11.68 Position C (crest closets) u z ( cm ) ( cm s ) ( cm ) 1.13 2.63 4.20 5.63 7.12 8.85 10.20 11.45 12.84 14.35 18.00 20.79 23.73 26.70 29.70 u ( cm s) 6.57 8.27 8.55 9.27 9.11 10.12 10.38 10.48 10.74 10.70 11.33 11.76 11.74 11.97 12.09 Stations A, B, C, D, E are shown in Figure 6.1 ( z ) was measured from local bottom. Brackets indicates that the vertical profiling is nearest to the crest or trough of the bed ripple 241 I.2.2 ( H = 15.15cm, T = 1.5s ) Position A (trough closets) u z ( cm ) ( cm s ) 1.01 2.57 4.00 5.65 7.25 8.73 10.10 11.50 13.00 14.38 17.30 20.30 23.30 26.25 29.16 6.77 8.03 8.07 8.70 9.56 9.95 10.61 10.94 11.39 11.09 11.47 11.71 11.57 11.71 12.10 Position D (trough closets) z ( cm ) 1.40 3.10 4.72 6.00 7.50 9.00 10.60 12.05 13.26 14.88 17.86 20.70 23.96 26.84 29.30 u ( cm Position B (crest closets) u z ( cm ) ( cm s ) 1.40 3.06 4.39 5.74 7.35 8.79 10.10 11.75 13.09 14.64 17.76 20.78 23.72 26.72 29.74 6.18 6.95 8.52 8.75 9.36 9.60 10.09 9.71 10.48 10.30 10.72 11.21 11.34 11.80 12.51 1.43 2.91 4.27 5.87 7.30 8.95 10.10 11.34 12.79 14.30 17.31 6.63 7.36 8.32 9.00 9.85 9.68 10.55 10.62 10.88 11.05 11.40 Position E (trough closets) z s) 7.46 8.06 9.11 9.84 9.59 10.11 10.41 11.11 10.85 11.35 11.39 11.55 11.79 11.70 12.04 Position C (crest closets) u z ( cm ) ( cm s ) ( cm ) 0.92 2.50 4.01 5.66 7.42 9.00 10.52 11.67 13.14 14.57 17.69 20.39 23.41 26.41 29.41 u ( cm s) 6.16 7.34 7.22 9.17 9.12 9.59 10.57 10.13 11.01 11.25 11.33 11.90 11.65 12.09 12.26 Stations A, B, C, D, E are shown in Figure 6.1 ( z ) was measured from local bottom. Brackets indicates that the vertical profiling is nearest to the crest or trough of the bed ripple 242 I.3 Pure current (depth averaged 10.5cm/s) over wave-current formed ripples I.3.1 Wave ( H = 5.99cm, T = 1.5s )-Current ( U = 10.5 cm s ) formed ripples Position A (trough closets) u z ( cm ) ( cm s ) 1.08 2.48 3.98 5.40 6.91 8.78 10.03 11.50 12.76 14.10 17.12 20.10 23.01 26.10 28.88 I.3.2 6.61 7.85 8.63 9.76 10.02 9.96 10.12 10.66 10.88 11.01 11.01 11.32 11.47 11.55 11.54 z 0.90 2.49 3.96 5.30 6.94 8.23 9.84 11.34 12.82 14.26 17.30 20.25 23.29 26.31 29.20 2.38 4.00 5.50 7.02 8.61 9.86 11.15 12.69 14.10 17.13 20.12 23.11 25.95 29.04 8.14 8.79 9.41 9.75 10.26 10.23 10.60 10.68 10.88 10.95 11.05 11.36 11.57 11.96 Position C (trough closets) u z ( cm ) ( cm s ) 0.73 2.50 3.90 5.31 6.73 8.17 9.67 11.30 12.63 14.10 17.14 20.22 23.30 26.18 27.20 7.87 9.23 9.56 10.11 10.56 10.85 11.10 11.04 11.16 11.25 11.43 11.77 11.81 12.22 12.11 Wave ( H = 5.96cm, T = 1.5s )- Current ( U = 13.5 cm s ) formed ripples Position A (crest closets) ( cm ) Position B (crest closets) u z ( cm ) ( cm s ) u ( cm Position B (trough closets) z s) 6.59 7.47 8.25 8.45 9.50 9.64 9.59 10.45 10.49 10.71 11.23 11.40 11.89 12.02 12.12 ( cm ) 1.19 2.15 3.55 5.11 6.83 8.60 10.05 11.47 12.95 14.41 17.40 20.34 23.21 26.31 28.11 u ( cm Position C (crest closets) z s) 6.11 7.33 7.98 8.73 9.11 9.26 9.70 10.24 9.91 10.70 11.27 11.65 11.52 12.17 12.05 ( cm ) 1.14 2.72 4.27 6.01 7.20 8.57 10.14 11.56 12.98 14.37 17.40 20.49 23.45 26.44 u ( cm s) 8.01 8.76 9.02 9.68 10.09 10.14 10.27 10.92 11.12 11.53 11.80 12.18 12.67 12.62 Stations A, B, C are shown in Figure 6.1 ( z ) was measured from local bottom. Brackets indicates that the vertical profiling is nearest to the crest or trough of the bed ripple 243 I.3.3 Wave ( H = 9.84cm, T = 1.5s )-Current ( U = 10.5 cm s ) formed ripples Position A (crest closets) z ( cm ) 0.96 2.51 4.24 5.94 7.47 8.83 10.16 11.58 12.91 14.36 17.54 20.51 23.47 26.50 29.40 I.3.4 u ( cm z s) 5.22 6.85 7.89 8.16 9.28 9.39 9.50 9.91 10.08 10.27 10.66 10.64 11.03 11.31 11.07 z 1.25 2.72 4.21 5.61 7.23 8.74 10.11 11.60 13.21 14.67 17.64 20.61 23.59 26.59 29.55 ( cm ) 1.10 2.53 4.10 5.43 6.91 8.56 10.01 11.31 12.88 14.40 17.91 20.74 23.73 26.73 29.69 u ( cm Position C (trough closets) z s) 6.90 7.38 7.59 9.07 9.58 9.42 9.67 10.14 10.17 10.43 10.65 10.83 10.81 11.08 11.56 ( cm ) 0.98 2.57 4.10 5.53 7.07 8.61 10.11 11.24 12.70 14.02 17.15 20.24 23.14 26.30 u ( cm s) 7.41 8.56 8.95 9.36 9.71 10.05 10.78 10.87 10.79 11.04 11.36 11.27 11.78 11.93 Wave ( H = 9.91cm, T = 1.5s )-Current ( U = 13.5 cm s ) formed ripples Position A (trough closets) ( cm ) Position B (crest closets) u ( cm Position B (crest closets) z s) 6.24 7.30 7.81 8.79 9.26 9.29 9.83 9.86 9.81 10.08 10.30 10.44 10.82 10.94 11.36 ( cm ) 1.19 2.75 4.50 5.69 7.23 8.88 10.38 11.67 13.18 14.46 17.61 20.53 23.46 26.51 29.35 u ( cm Position C (crest closets) z s) 6.42 7.54 8.41 8.89 9.31 9.38 9.84 9.76 10.08 9.98 10.44 10.72 11.15 11.20 11.49 ( cm ) 1.37 2.74 4.32 6.33 7.25 9.03 10.09 11.51 13.07 14.63 17.60 21.00 23.64 26.00 u ( cm s) 7.23 7.91 9.10 9.32 10.01 10.01 10.49 10.83 10.81 11.06 11.21 11.45 11.67 11.87 Stations A, B, C are shown in Figure 6.1 ( z ) was measured from local bottom. Brackets indicates that the vertical profiling is nearest to the crest or trough of the bed ripple 244 I.3.5 Wave ( H = 15.27cm, T = 1.5s )-Current ( U = 10.5 cm s ) formed ripples Position A (trough closets) z ( cm ) 1.15 2.45 3.93 5.56 7.12 8.41 9.91 11.51 12.86 14.28 17.39 20.33 23.33 26.26 28.29 I.3.6 u ( cm z s) 5.76 7.23 8.03 8.38 8.99 9.56 9.51 10.14 10.12 10.21 10.68 10.75 10.85 11.09 11.58 z 1.30 2.73 4.13 5.53 7.14 8.74 10.21 11.41 12.71 14.40 17.51 20.33 23.20 26.23 29.13 ( cm ) 1.10 2.80 4.10 5.54 7.10 8.53 10.05 11.55 12.84 14.45 17.45 20.39 23.25 26.27 29.11 u ( cm Position C (trough closets) z s) 6.61 7.64 8.10 8.90 9.42 9.44 9.80 10.05 10.35 10.41 10.66 11.05 11.20 11.40 11.77 ( cm ) 0.99 2.70 4.07 5.49 7.02 8.52 9.97 11.49 12.87 14.48 17.49 20.37 23.41 26.54 29.41 u ( cm s) 6.95 7.71 8.97 9.22 9.21 9.76 9.85 9.89 9.86 10.35 10.91 11.16 11.51 11.58 11.79 Wave ( H = 15.4cm, T = 1.5s )-Current ( U = 13.5 cm s ) formed ripples Position A (crest closets) ( cm ) Position B (crest closets) u ( cm Position B (trough closets) z s) 6.13 6.74 7.99 8.32 8.76 9.28 9.25 9.97 9.92 10.31 10.26 11.01 11.21 11.37 11.46 ( cm ) 1.45 2.96 4.27 5.72 7.19 8.62 10.01 11.56 13.00 14.56 17.00 20.58 23.50 26.50 29.32 u ( cm Position C (trough closets) z s) 7.52 8.37 8.70 9.31 9.51 9.64 10.04 10.31 10.36 10.46 11.06 11.04 11.37 11.73 11.83 ( cm ) 1.11 2.45 3.94 5.44 6.92 8.40 9.94 11.46 12.79 14.36 17.20 20.40 23.29 26.40 28.32 u ( cm s) 8.06 8.45 8.96 9.39 9.75 9.96 10.13 10.53 10.81 10.75 11.47 11.43 11.73 12.15 12.09 Stations A, B, C are shown in Figure 6.1 ( z ) was measured from local bottom. Brackets indicates that the vertical profiling is nearest to the crest or trough of the bed ripple 245 I.4 Current directional mean velocity distribution in wave-current combined flow over the movable bed I.4.1 Measurements at Station A H = 6.00cm, T = 1.5s H = 10.51cm, T = 1.5s H = 17.49cm, T = 1.5s U = 10.5 cm s (trough closets) u z ( cm ) ( cm s ) U = 10.5 cm s (crest closets) u z ( cm ) ( cm s ) U = 10.5 cm s (trough closest) u z ( cm ) ( cm s ) 1.20 2.80 4.50 6.20 8.00 9.86 11.50 12.30 13.61 14.70 17.59 20.54 23.65 26.70 4.92 6.73 8.43 9.15 9.93 10.15 10.17 10.56 10.69 10.82 11.33 11.66 12.06 12.34 1.00 2.66 4.03 5.63 8.04 9.54 11.04 12.54 13.42 14.92 17.30 20.33 23.33 26.13 5.23 6.62 7.73 9.42 10.08 10.23 10.94 11.22 11.63 11.68 12.06 12.33 12.36 12.32 1.05 2.50 4.00 5.50 7.00 8.50 10.00 11.50 13.00 14.50 17.50 20.50 23.50 5.70 7.20 8.45 9.71 10.79 11.38 11.64 12.19 12.46 12.99 12.88 12.99 13.16 H = 8.62cm, T = 1.5s H = 11.67cm, T = 1.5s H = 15.07cm, T = 1.5s U = 13.5 cm s (crest closets) U = 13.5 cm s U = 13.5 cm s (trough closets) u z ( cm ) ( cm s ) (crest closets) u z ( cm ) ( cm s ) z ( cm ) u ( cm s ) 1.30 2.80 4.40 5.80 7.20 8.44 10.13 11.64 13.10 14.44 17.50 20.47 23.51 26.51 6.25 8.10 9.54 10.60 11.96 12.30 12.86 13.12 13.47 13.99 14.24 14.66 15.04 15.21 1.37 2.87 4.50 5.73 7.23 8.80 10.47 12.54 13.64 14.80 18.21 20.90 24.15 5.38 7.87 9.26 10.72 11.04 12.25 12.99 13.28 13.45 13.85 14.15 14.27 15.29 1.10 2.60 4.10 5.60 7.10 8.60 10.10 11.60 13.10 14.60 17.60 20.60 23.60 7.68 9.48 10.59 12.43 13.63 14.12 14.54 15.17 15.51 15.93 16.25 16.32 16.28 Position of Stations A is shown in Figure 6.1 ( z ) was measured from local bottom. Brackets indicates that the vertical profiling is nearest to the crest or trough of the bed ripple 246 I.4.2 Measurements at Station B H = 7.18cm, T = 1.5s H = 11.28cm, T = 1.5s H = 18.64cm, T = 1.5s U = 10.5 cm s (crest closets) U = 10.5 cm s (crest closets) U = 10.5 cm s (crest closets) u z ( cm ) 0.80 2.30 3.60 5.30 6.80 8.30 9.77 11.31 12.90 14.40 17.15 20.10 23.14 26.00 ( cm z s) 3.22 4.92 7.09 8.15 8.76 9.64 9.85 10.09 10.50 10.93 11.43 11.38 11.63 12.20 ( cm ) 1.45 2.95 4.30 5.95 7.45 8.87 10.37 11.87 13.08 14.58 17.55 20.55 23.84 u ( cm u z s) 4.45 6.44 8.03 9.09 9.85 10.40 10.89 11.61 11.55 11.60 12.00 12.11 12.25 ( cm ) 1.30 2.80 4.30 5.80 7.30 8.80 10.30 11.80 13.30 14.80 17.80 20.80 22.80 ( cm s) 2.59 6.42 8.14 9.74 10.56 11.30 11.73 12.04 12.52 13.09 13.37 13.16 13.06 H = 7.72cm, T = 1.5s H = 13.34cm, T = 1.5s H = 18.64cm, T = 1.5s U = 13.5 cm s (trough closets) U = 13.5 cm s (crest closets) U = 13.5 cm s (trough closets) z ( cm ) 1.15 2.56 4.07 5.64 7.06 8.49 9.83 11.10 12.60 14.20 17.25 20.30 23.36 26.39 u ( cm z s) 4.99 7.34 9.43 10.16 11.26 12.15 12.90 12.47 13.51 13.89 13.89 15.18 15.41 15.20 ( cm ) 1.78 3.28 5.00 4.00 5.50 8.30 9.80 11.47 13.20 14.80 17.43 20.40 23.49 u ( cm z s) 6.08 8.23 9.53 10.06 11.16 12.41 12.97 13.29 14.03 14.07 14.64 15.38 15.31 ( cm ) 1.03 2.53 4.03 5.53 7.03 8.53 10.03 11.53 13.03 14.53 17.53 20.53 22.03 u ( cm s) 6.67 8.56 11.09 13.59 13.99 14.92 15.54 16.33 16.57 16.52 16.82 17.00 16.57 Position of Stations B is shown in Figure 6.1 ( z ) was measured from local bottom. Brackets indicates that the vertical profiling is nearest to the crest or trough of the bed ripple 247 I.4.3 Measurements at Station C H = 5.75cm, T = 1.5s H = 9.49cm, T = 1.5s H = 15.73cm, T = 1.5s U = 10.5 cm s (trough closets) U = 10.5 cm s (trough closets) U = 10.5 cm s (trough closets) z ( cm ) 0.90 2.20 4.00 5.90 7.40 8.97 10.30 11.50 13.00 14.33 17.54 20.40 23.00 25.00 u ( cm z s) 4.33 6.28 7.67 8.82 9.85 10.18 10.34 10.70 10.69 10.95 11.46 11.82 12.04 12.33 ( cm ) 1.10 2.60 4.10 5.60 7.30 9.03 10.53 12.03 13.53 15.03 18.00 21.00 23.50 u ( cm u z s) 4.85 6.40 8.87 10.07 10.86 11.29 11.76 12.15 11.90 12.33 12.37 12.47 12.44 ( cm ) 1.00 2.50 4.00 5.50 7.00 8.50 10.00 11.50 13.00 14.50 17.50 20.50 ( cm s) 3.88 6.79 8.79 9.36 10.16 10.99 11.59 11.97 12.34 12.98 13.39 13.59 H = 7.19cm, T = 1.5s H = 11.12cm, T = 1.5s H = 16.56cm, T = 1.5s U = 13.5 cm s (crest closets) U = 13.5 cm s (crest closets) U = 13.5 cm s (trough closets) z ( cm ) 1.00 2.57 4.16 5.80 7.40 8.60 10.10 11.50 13.02 14.50 17.40 20.37 23.44 26.51 u ( cm z s) 5.57 8.29 10.70 11.60 12.09 12.63 12.87 13.65 13.60 14.20 14.09 14.93 15.66 15.92 ( cm ) 0.89 2.45 3.60 5.27 6.41 7.88 9.69 11.15 12.15 13.41 16.66 19.64 22.54 u ( cm z s) 5.56 6.19 9.24 10.99 12.67 12.84 13.48 14.00 14.34 14.70 15.37 15.75 15.76 ( cm ) 1.27 2.77 4.27 5.77 7.27 8.77 10.27 11.77 13.27 14.77 17.77 20.77 23.27 u ( cm s) 6.87 8.75 10.54 12.86 14.27 15.67 15.73 16.31 16.75 17.21 17.21 16.90 16.85 Position of Stations C is shown in Figure 6.1 ( z ) was measured from local bottom. Brackets indicates that the vertical profiling is nearest to the crest or trough of the bed ripple 248 I.4.4 Measurements at Station D H = 4.40cm, T = 1.5s H = 7.28cm, T = 1.5s H = 13.23cm, T = 1.5s U = 10.5 cm s (trough closets) U = 10.5 cm s (trough closets) U = 10.5 cm s (crest closets) u z ( cm ) 1.15 2.60 4.17 5.74 7.20 8.90 10.35 11.77 13.30 15.09 18.21 21.04 24.01 27.06 ( cm u z s) 4.59 6.17 7.58 8.86 9.82 10.36 10.74 11.05 11.16 11.54 11.78 11.90 12.25 12.31 ( cm ) 1.20 2.70 4.52 6.02 7.52 9.02 10.52 12.02 13.52 15.02 18.02 21.00 24.00 27.00 ( cm u z s) 2.02 4.75 6.75 7.92 8.86 9.25 9.79 10.71 10.47 11.08 11.64 11.79 12.07 11.98 ( cm ) 1.29 2.79 4.29 5.79 7.29 8.79 10.29 11.79 13.29 14.79 17.79 20.79 ( cm s) 4.58 6.08 7.93 8.94 10.11 11.19 11.44 12.03 12.12 12.66 12.52 12.76 H = 5.63cm, T = 1.5s H = 8.45cm, T = 1.5s H = 12.13cm, T = 1.5s U = 13.5 cm s (trough closets) U = 13.5 cm s (trough closets) U = 13.5 cm s (trough closets) z ( cm ) 1.10 2.80 4.28 5.86 7.41 8.86 10.50 11.90 13.05 14.36 17.34 20.40 23.44 26.61 u ( cm z s) 5.11 7.61 9.33 10.72 11.67 12.20 12.90 13.00 13.26 13.74 14.03 14.44 14.63 15.32 ( cm ) 1.08 2.58 4.08 5.58 7.08 8.58 10.08 11.58 13.08 14.21 17.21 20.21 23.40 26.20 u ( cm z s) 5.28 7.12 8.55 10.92 11.21 12.60 12.98 13.78 14.10 14.29 14.78 15.11 15.08 14.98 ( cm ) 1.33 2.83 4.33 5.83 7.33 8.83 10.33 11.83 13.33 14.83 17.83 20.83 23.83 26.83 u ( cm s) 2.79 7.36 9.51 11.61 12.72 13.06 14.15 14.82 15.63 15.41 15.87 16.55 16.55 16.18 Position of Stations D is shown in Figure 6.1 ( z ) was measured from local bottom. Brackets indicates that the vertical profiling is nearest to the crest or trough of the bed ripple 249 I.4.5 Measurements at Station E H = 9.85cm, T = 1.5s H = 15.36cm, T = 1.5s H = 21.80cm, T = 1.5s U = 10.5 cm s (crest closets) U = 10.5 cm s (trough closets) U = 10.5 cm s (trough closets) z ( cm ) 1.16 2.74 4.44 5.85 7.23 8.46 10.02 11.55 13.00 14.42 17.42 20.40 23.35 24.81 u ( cm z s) 6.03 8.73 10.27 11.09 10.87 11.27 11.31 11.78 11.91 12.12 12.15 12.41 12.62 12.40 ( cm ) 1.30 2.62 4.46 6.22 7.70 8.38 10.87 11.51 12.67 14.40 17.35 20.47 22.75 u ( cm z s) 3.94 5.53 7.00 8.20 8.99 10.28 10.14 10.54 11.57 11.82 12.14 12.16 12.36 ( cm ) 0.85 2.35 3.85 5.35 6.85 8.35 9.85 11.35 12.85 14.35 17.35 20.35 u ( cm s) 2.43 4.30 4.65 5.32 6.44 7.85 8.33 9.30 9.76 10.25 11.43 12.06 H = 9.50cm, T = 1.5s H = 14.89cm, T = 1.5s H = 21.73cm, T = 1.5s U = 13.5 cm s (crest closets) U = 13.5 cm s (crest closets) U = 13.5 cm s (crest closets) z ( cm ) 0.70 2.54 4.00 5.51 7.20 8.70 10.20 11.50 12.90 14.50 17.44 20.40 23.43 26.30 u ( cm z s) 8.62 10.05 12.03 12.91 12.88 13.31 14.21 14.37 14.50 14.57 15.20 15.36 15.71 15.74 ( cm ) 0.90 3.20 4.63 6.30 7.80 8.70 10.40 11.48 12.70 14.60 17.58 20.45 23.71 u ( cm z s) 6.23 8.16 9.99 11.63 12.67 13.29 14.05 13.93 14.80 14.59 15.43 15.09 15.38 ( cm ) 1.40 2.90 4.40 5.90 7.40 8.90 10.40 11.90 13.40 14.90 17.90 20.90 u ( cm s) 5.53 7.11 9.95 11.20 12.73 14.38 15.20 15.80 16.18 16.88 17.53 17.57 Position of Stations E is shown in Figure 6.1 ( z ) was measured from local bottom. Brackets indicates that the vertical profiling is nearest to the crest or trough of the bed ripple 250 Height above bottom (cm) 35 30 25 20 15 Location A H = 10.51cm 10 U = 10.5 cm s z0 = 0.0544cm 0 Height above bottom (cm) 35 10 12 Velocity (cm/s) 14 16 18 20 30 25 20 15 Location A H = 17.49cm 10 U = 10.5 cm s z0 = 0.0394cm 0 Height above bottom (cm) 35 10 12 Velocity (cm/s) 14 16 18 20 30 25 20 15 Location B H = 7.72cm 10 U = 13.5 cm s z0 = 0.0519cm 0 Height above bottom (cm) 35 10 12 Velocity (cm/s) 14 16 18 20 30 25 20 15 Location B H = 13.40cm 10 U = 13.5 cm s z0 = 0.0202cm 0 10 12 Velocity (cm/s) 14 16 18 20 251 Height above bottom (cm) 35 30 25 20 15 Location D H = 4.4cm 10 U = 10.5 cm s z0 = 0.0085cm 0 Height above bottom (cm) 35 10 12 Velocity (cm/s) 14 16 18 20 30 25 20 15 Location D H = 7.28cm 10 U = 10.5 cm s z0 = 0.0141cm 0 Height above bottom (cm) 35 10 12 Velocity (cm/s) 14 16 18 20 30 25 20 15 Location D H = 13.23cm 10 U = 10.5 cm s z0 = 0.0219cm 0 Height above bottom (cm) 35 10 12 Velocity (cm/s) 14 16 18 20 30 25 20 15 Location D H = 5.63cm 10 U = 13.5 cm s z0 = 0.0519cm 0 10 12 Velocity (cm/s) 14 16 18 20 252 Height above bottom (cm) 35 30 25 20 15 Location D 10 H = 8.45cm U = 13.5 cm s z0 = 0.0202cm 0 Height above bottom (cm) 35 10 12 Velocity (cm/s) 14 16 18 20 30 25 20 15 Location D 10 H = 12.13cm U = 13.5 cm s z0 = 0.0098cm 0 Height above bottom (cm) 35 10 12 Velocity (cm/s) 14 16 18 20 30 25 20 15 Location E 10 H = 15.36cm U = 10.5 cm s z0 = 0.0141cm 0 Height above bottom (cm) 35 10 12 Velocity (cm/s) 14 16 18 20 30 25 20 15 Location E 10 H = 14.89cm U = 13.5 cm s z0 = 0.0202cm 0 10 12 Velocity (cm/s) 14 16 18 20 Figure I.1. Measurements of time mean current velocities ( ) of wave-current perpendicular interaction, predictions by Christoffersen and Jonsson (1985) ( ), Fredsǿe (1984) ( ), Grant and Madsen (1986) (one point ) and present (depth averaged ;one point ) models . For one point prediction the reference velocity was taken at about 0.3h (water depth h = 35cm , wave period T = 1.5s ) 253 Publications 1. M.P.C. Fernando, J. Guo., Y.S. Wu, “Experimental study on the interaction of waves normal to current in a wave basin” Tenth Asian Congress of Fluid Mechanics 2004. Peradeniya, Sri Lanka. (Paper No. C26) 2. M.P.C. Fernando, P. Lin., “Experimental determination of friction coefficient and velocity profiles for wave-current perpendicular interaction” The fifth international Symposium on ocean wave measurements and analysis, Madrid, Spain. (Paper No. 284) 3. M.P.C. Fernando, J. Guo, “Laboratory study of eddy viscosity structure under wave-current interaction” Invited paper for AOGS 2005; (Asia Oceania Geosciences Society’s 2nd Annual meeting). Singapore. (Paper No. 58-OAA0115) 4. M.P.C. Fernando, J. Guo., P. Lin, Wave-current interaction at an angle – Part I : Experiments. (under preparation for journal publication) 5. M.P.C. Fernando, P. Lin, J. Guo., Wave-current interaction at an angle – Part II : Theory. (under preparation for journal publication) 6. Experimental study on sediment transport and bed ripple geometry under orthogonal wave-current flow (under preparation for journal publication) 254 [...]... previous experimental studies on combined wave- current flow have been conducted for parallel wave- current conditions and theoretical models lack validation for 900 wave- current motions The purpose of this study was to investigate flow kinematics and sediment transport experimentally for orthogonal wave- current flow to validate existing theories and to develop a new theoretical model to describe wave- current. .. suspension properties and sediment transport rate under pure wave, pure current and wave- current interaction over flat concrete and movable rippled sand bed are required to provide an improved understanding of the complex non-linear wave- current interaction mechanisms However, due to the limitation of experimental facilities especially wave basins and difficulty of generating and controlling the required wave. .. and currents are considered For example, in the design of offshore jackets both wave and current loadings are considered and marine structures undergo erosion of sediment around their bases due to scouring action of waves and tidal currents Therefore a complete understanding of flow kinematics and bed dynamics under wave- current interaction is important and necessary to study the coastal processes on. .. pure currents A similar sediment transport process is observed in the near shore region where both waves and currents are important in determining the sediment budget and 8 therefore in the study of longshore sediment transport, attention of wave- current perpendicular interaction is necessary In the wave- current interaction, the total sediment transport can be divided into current- related and wave- related... orientations, waves co-exist with currents on continental shelves Effects of combined wave- current flow on many coastal practices are significant and therefore, during the past four decades many researchers have contributed experimentally and theoretically to the understanding of wave- current interaction mechanisms This thesis presents an experimental investigation of orthogonal wave- current flow The study. .. wave and current flows in wave basins, only very few experimental data are available for wave- current flow interactions at arbitrary angles in comparison to flume experimental data which describe only following or opposing currents with waves Physically modeling the wave- current orthogonal interactions in wave flumes by mechanical means of bed oscillation perpendicular to current flow direction could... effect on flow kinematics and bed dynamics of the combined flow Scarcity of available data on wave- current interactions at arbitrary angles is a major shortcoming on studies of wave- current flows to investigate how the interaction angles affect the flow Unlike wave flumes, wave basins can be used to conduct experiments to investigate wavecurrent interactions at any angle But, uniform steady current flow. .. behaviour in the continental shelf Many coastal processes on the continental shelf are governed by the interaction of waves and currents On many continental shelves, re-suspension of sediments by energetic waves and currents is the dominant mechanism for sediment transport Once sediment is suspended by waves, it is transported by currents that can redistribute sediment on the shelf The along-shelf transport. .. angle wave- current flows Some modifications for these theoretical models are proposed to better describe orthogonal wave- current interaction The method of Bijker (1971) accords with measurements of suspension and current related sediment transport quantity under orthogonal wave- current flow Based on time-variant bed shear stress of the combined flow, a new theory is developed to describe the interaction. .. wave- current flow at arbitrary angle interactions A physical model was constructed in a 3-D wave basin to reproduce orthogonal wave- current flow over both the flat concrete and movable sand bed Experimental runs were conducted for pure currents, pure waves and combined wavecurrent flows for the measurements of three directional velocities, water surface elevations, bed profile geometries, suspended sediment concentrations . EXPERIMENTAL STUDY ON FLOW KINEMATICS AND SEDIMENT TRANSPORT UNDER ORTHOGONAL WAVE- CURRENT INTERACTION M. PRADEEP CHAMINDA FERNANDO NATIONAL. 2006 EXPERIMENTAL STUDY ON FLOW KINEMATICS AND SEDIMENT TRANSPORT UNDER ORTHOGONAL WAVE- CURRENT INTERACTION M. PRADEEP CHAMINDA FERNANDO (B.Sc.Eng. (Hons.), University. describe orthogonal wave- current interaction. The method of Bijker (1971) accords with measurements of suspension and current related sediment transport quantity under orthogonal wave- current flow.