Numerical Analysis to Design a Hydraulic-Control Wave-Maker (HCW) for the Study of Oceanographic Flows Haeng Sik Ko 1 , Patrick J. Lynett 1 1 Department of Civil and Environmental Engineering, University of Southern California, Los Angeles, CA − Piston type (Flux limitation) − Pump type (Pulsation problem) − a/h=0.05 (left): a/h=0.3 (right) − Reflection coefficient: 4.76% (a/h=0.05) & 2.56% (a/h=0.3) − a/h=0.05 (left): a/h=0.3 (right) − Reflection coefficient: 4.78% (a/h=0.05) & 2.10% (a/h=0.3) 2) Optimized baffle: a/h=0.01, kh=1 Absorbing wave reflection 2 − Extract horizontal velocity data any point − The data averaged and applied along outlet boundary − Using wave celerity, time shifting is computed Absorbing wave reflection 1 − Extract horizontal velocity data near outlet boundary (Experimentally this would be done in real time with ADV) − The data averaged and applied along outlet boundary (Experimental radiation boundary condition) 3) Optimized baffle: a/h=0.05, kh=0.1 Sensitivity analysis − Baffle length, number and position 4) Optimized baffle: a/h=0.05, kh=1 1) Optimized baffle: a/h=0.01, kh=0.1 Design of the optimized baffle − 10 baffles are located over wave amplitude range of a/h=0.05 − Baffle length: 0.05m 2) Baffle number & position (a/h=0.05, kh=1) − To create various amplitude wave, lots of baffles should be positioned INTRODUCTION Motivation − The lack of experimental studies with respect to complex oceanographic flows: Nonlinear & multi-scale physics − General wave-maker techniques (Dean & Dalrymple, 1991) have been used, based on dispersive & shallow water theory, linear to weakly nonlinear waves theory Objective of HCW − Develop new experimental device to study multi-scale and vertically-variable oceanographic flows − Design HCW by numerical analysis (OpenFOAM® ) 1) Ability of wave generation and absorption: Compared to analytical solution 2) Optimized HCW: Sensitivity analysis METHODOLOGY HCW system − Inlet and outlet boundaries: a set of vertical baffles − Each baffle connected to an individual pump − The controllable vertical distribution of flow − Horizontal particle velocities along water depth are averaged over each baffle height − The averaged velocities are imposed at each baffle as inlet condition − Any arbitrary flow can be reasonably created − Different sets of baffles can be connected to different reservoirs to create vertical density profiles SENSITIVITY ANALYSIS SENSITIVITY ANALYSIS RESULTS AND ANALYSES 1) Baffle length (a/h=0.05, kh=1, 3 inlet case) − Baffle length ranges from 0.05 to 0.3 RESULTS AND ANALYSES SUMMARY − A new method of wave generation and absorption by using HCW is verified through numerical analysis. − The optimized design of HCW is found through sensitivity analyses, such baffle length, number and position. − Preliminary results using a small-scale physical model of a HCW will be presented. REFERENCES 1. R. Dean, R. Dalrymple, (1991) Water Wave Mechanics for Engineers and Scientists, World Scientific. FUTURE WORK