Engineering analysis of turbulent flow measurements near Kuchinoshima Island

Abstract

Ocean current measurements from near Kuchinoshima Island are analyzed to consider turbulence characteristics with regard to the engineering design of an ocean current turbine. The location of the measurements is offshore of Kuchinoshima in the Tokara Strait within the path of the Kuroshio Current. The measurement campaign was from January 15 to 16, 2016 using the Nortek Signature 500 ADCP and Nortek Vector ADV. Turbulence characteristics of turbulence intensity, integral timescale, and integral length scale are evaluated at 1 m increments above the seabed. Doppler noise removal is performed and power density spectrums are presented. The findings will lead to more accurate loading calculations and simulations for performance evaluation.

Turbulent flow structure over rough side-wall surface under wave-against-current motion

“…Similar phenomenon was also reported by Novo and Kyozuka 51 in a field study at a natural channel under the tidal current flow conditions. Recently in the study of Imamura et al,52 similar pattern of autocorrelation function was reported. The autocorrelation function estimation locations, y/B = 0.02, 0.1, 0.5 and 1 represent the region close to the wall, mid-region and far-region from the wall.…”

Comparison of ADCP measurements to Kuroshio current flow simulations for ocean current turbines

“…5 Since 2011, development of a single point moored, floating, twin turbine has been underway to harness the energy of the Kuroshio Current and various elements of the flow conditions have been studied. 6,7 The device design being considered in this work is meant to operate submerged in the midwater column utilizing large ;15 m diameter turbine blades. This small size ocean current turbine is estimated to generate about 200 kW, suitable for a small demand load, such as that of a small remote island.…”

Application of acoustic Doppler current profilers in predicting contaminant transport in channels

“…If the ADCP could accurately capture other turbulence quantities, such as Reynolds stress (e.g., or turbulent kinetic energy (e.g., Imamura et al, 2018;, the transverse mixing coefficient could potentially be extracted as well by combining measurements with additional information on the water body. Methods for calculating turbulent kinetic energy (TKE) from an ADCP in literature (1) make assumptions regarding the flow (e.g., , (2) position the ADCP or ADCPs strategically with certain beam sets (e.g., Guerra and Thompson, 2017;Imamura et al, 2018), or (3) measure not the true value of TKE but indicate the relative strength of turbulence in the water column (e.g., . A method that is simple to apply, can be used with any ADCP, and produces accurate estimates of TKE would be useful in predicting mixing and transport in rivers.…”

“…Reynolds stresses have been used to assess performances of stream barbs and estimate eddy diffusivities and mixing times in a coastal river . Turbulent kinetic energy (TKE) is also important for several applications, such as modeling turbulence in tidal currents (Garcia Novo and Kyozuka, 2020), characterizing mixing for invasive species control in a large lake , and measuring anticipated tidal energy for turbine design (Imamura et al, 2019).…”

“…Choosing the orientation of the ADCP cleverly or adding beams can avoid the assumption of statistical homogeneity and its associated errors. An ADCP with a beam oriented along one of the three coordinate directions can accurately measure the root mean squared (RMS) velocity in that direction (e.g., Imamura et al, 2018), but because of the available beam orientations, computing the other two RMS velocities likely requires further assumptions.…”