Structure of turbulent flow in EMEC's tidal energy test site

Abstract Measurements of bulk turbulent parameters (Kinetic energy, dissipation rates, Reynolds stress, etc.) were performed in the bottom boundary layer of the European Marine Energy Centre (EMEC) tidal test site using Acoustic Doppler Current Profilers (ADCPs). Flood and ebb currents exceed 1.4 ms− 1 near the seabed (at 2.63 mab) and generate > 7 Pa stresses. The production of turbulent kinetic energy (TKE) P , was found to be negative below 2 × 10 − 9  Wm − 3 and, of up to 5 × 10 − 4  Wm − 3 was estimated during flood flows and decreasing to 10 − 5  Wm − 3 during slack water. The TKE dissipation rate e was estimated using the structure function method with greatest value of up to 5 × 10 − 1  Wm − 3 near the seabed around maximum flood, falling to 4 × 10 − 3  Wm − 3 around slack water. The comparison between P and e was performed by calculating individual ratios of P corresponding to e using a bootstrap resampling technique. The study shows that the ratio e / P averaged over whole flood and ebb were found to be ~ 0.3553 and ~ 0.3266, respectively, indicating that production exceeds dissipation. The uncertainties in Reynolds stress estimates due to instrument noise was found to be 4 × 10 − 4  Pa.