scholarly journals A Simple Nozzle-Diffuser Duct Used as a Kuroshio Energy Harvester

2021 ◽  
Author(s):  
Po-Hung Yeh ◽  
Shang-Yu Tsai ◽  
Wei-Ren Chen ◽  
Shing-Nan Wu ◽  
Meng-Chang Hsieh ◽  
...  
Keyword(s):  
Energy Demand ◽  
Energy Harvester ◽  
Normal Wave ◽  
Sea Surface ◽  
Ocean Current ◽  
Ansys Fluent ◽  
Wave Condition ◽  
Storm Wave ◽  
Engineering Practices ◽  
The Kuroshio

In response to the increasing energy demand in Taiwan and the global trend of renewable energy development, Kuroshio energy is a potential energy source. How to extract this invaluable natural resource has then become an intriguing and important question in engineering practices. This study conducted a study for a nozzle-diffuser duct (NDD) as the Kuroshio currents energy harvester. The computational fluid dynamics (CFD) software ANSYS Fluent was employed to calculate the drag and added mass coefficients of the duct anchored to the seabed. Those coefficients were further imported into Orcaflex to simulate the motion of the duct under normal and storm wave conditions. Results showed that the duct was stable 25 m below the sea surface under normal wave condition. When the wave condition changed to storm waves, the duct needed to dive into at least 90 m below the sea surface to regain its stability and obtain high power take-off (PTO). An optimal design nozzle-diffuser-duct was reported and a PTO peak of 15 kW was expectable in the Kuroshio currents. Once a suitable offshore platform can be developed with sixty-six NDDs, a Megawatt Kuroshio ocean current power generation system is feasible in the near future.

scholarly journals A Simple Nozzle-Diffuser Duct Used as a Kuroshio Energy Harvester

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1552
Author(s):  
Po-Hung Yeh ◽  
Shang-Yu Tsai ◽  
Wei-Ren Chen ◽  
Shing-Nan Wu ◽  
Meng-Chang Hsieh ◽  
...  
Keyword(s):  
Energy Demand ◽  
Energy Harvester ◽  
Normal Wave ◽  
Sea Surface ◽  
Ocean Current ◽  
Ansys Fluent ◽  
Wave Condition ◽  
Storm Wave ◽  
Wave Conditions ◽  
The Kuroshio

In response to the increasing energy demand in Taiwan and the global trend of renewable energy development, Kuroshio energy is a potential energy source. How to extract this invaluable natural resource has then become an intriguing and important question in engineering practices. This study reported the results of a feasibility study for a nozzle-diffuser duct (NDD) as the Kuroshio currents energy harvester. The computational fluid dynamics (CFD) software ANSYS Fluent was employed to calculate the drag and added mass coefficients of the duct anchored to the seabed. Those coefficients were further imported into Orcaflex to simulate the motion of the duct under normal and storm wave conditions. Results showed that the duct was stable 25 m below the sea surface under normal wave conditions. When the wave condition changed to storm waves, the duct needed to dive into at least 90 m below the sea surface to regain its stability and obtain high power take-off (PTO). An optimal design nozzle-diffuser-duct was reported, and a PTO peak of 15 kW was expectable in the Kuroshio currents. Once a suitable offshore platform can be developed with sixty-six NDDs, a Megawatt Kuroshio ocean current power generation system is feasible in the near future.

scholarly journals The Role of Back Pressure in the Atmospheric Response to Surface Stress Induced by the Kuroshio

2017 ◽  
Vol 74 (2) ◽  
pp. 597-615 ◽  
Author(s):  
Kohei Takatama ◽  
Niklas Schneider
Keyword(s):  
Boundary Layer ◽  
Wind Stress ◽  
Back Pressure ◽  
Ocean Currents ◽  
Sea Surface ◽  
Ocean Current ◽  
Wind Stress Curl ◽  
General Response ◽  
The Kuroshio

Abstract The effect of ocean current drag on the atmosphere is of interest as a test case for the role of back pressure, because the response is independent of the thermally induced modulation of the boundary layer stability and hydrostatic pressure. The authors use a regional atmospheric model to investigate the impact of drag induced by the Kuroshio in the East China Sea on the overlying winter atmosphere. Ocean currents dominate the wind stress curl compared to the impacts of sea surface temperature (SST) fronts. Wind stress convergences and divergences are weakly enhanced even though the ocean current is almost geostrophic. These modifications change the linear relationships (coupling coefficients) between the wind stress curl/divergence and the SST Laplacian, crosswind, and downwind gradients. Clear signatures of the ocean current impacts are found beyond the sea surface: sea surface pressure (back pressure) decreases near the current axis, and precipitation increases over the downwind region. However, these responses are very small despite strong Ekman pumping due to the current. A linear reduced gravity model is used to explain the boundary layer dynamics. The linear vorticity equation shows that the oceanic influence on wind stress curl is balanced by horizontal advection decoupling the boundary layer from the interior atmosphere. Spectral transfer functions are used to explain the general response of back pressure to geostrophic ocean currents and sea surface height.

scholarly journals Upper Jurassic Bedded Limestones and Early Diagenetic Dolomitized Limestones in the Light of Mineralogical, Geochemical and Sedimentological Studies; Kraków Area, Poland

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 462
Author(s):  
Marcin Krajewski ◽  
Piotr Olchowy
Keyword(s):  
Clay Minerals ◽  
Normal Wave ◽  
Upper Jurassic ◽  
Reef Facies ◽  
Sedimentary Environments ◽  
Storm Wave ◽  
Microscopic Studies ◽  
Silica Alumina ◽  
Characteristic Features ◽  
Facies Types

This paper describes and analyzes the Upper Jurassic (Lower Kimmeridgian) succession exposed in the Zakrzówek Horst, located in the Kraków area. Three distinguished facies types FT 1-FT 3 comprise several limestone varieties: sponge-microbial, pelitic-bioclastic, and partly dolomitized detrital-bioclastic. Their sedimentary environments varied from relatively deeper, attaining storm-wave base, to more shallower, probably close to normal-wave base. Characteristic features of limestones are changes in contents of CaCO3 and insoluble residuum as well as porosity values in vertical transitional zones between facies types. The investigated facies types differ in sediment porosity dependent on development of limestones and its susceptibility to mechanical compaction during the early diagenesis. The studied limestones show high CaCO3 contents and minor insoluble residuum contents comprising quartz, chalcedony and clay minerals. No distinct variability occurs in contents of magnesium, silica, alumina and iron accumulated in clay minerals, iron oxides and oxyhydroxides, as well as in the amounts of amorphous silica. Early diagenetic dolomites, which occur locally within the limestones, were unrelated to fracture systems as possible pathways responsible for transfer of solutions rich in Mg2+ ions. The possible source of Mg2+ ions might have been the pore solutions, which migrated from compacted basinal bedded facies towards reef facies or the grain-supported bedded facies developed in the adjacent areas. Microscopic studies revealed dedolomitization at the surfaces and in the inner parts of dolomite crystals. In many cases, dolomite crystals were replaced by calcite forming pseudomorphs.

scholarly journals Impacts of the Kuroshio Intrusion through the Luzon Strait on the Local Precipitation Anomaly

2021 ◽  
Vol 13 (6) ◽  
pp. 1113
Author(s):  
Wen-Pin Fang ◽  
Ding-Rong Wu ◽  
Zhe-Wen Zheng ◽  
Ganesh Gopalakrishnan ◽  
Chung-Ru Ho ◽  
...  
Keyword(s):  
Kuroshio Current ◽  
Precipitation Anomaly ◽  
Luzon Strait ◽  
Sea Surface ◽  
Research Quality ◽  
Northwestern Pacific ◽  
Kuroshio Intrusion ◽  
Vertical Advection ◽  
Budget Analysis ◽  
The Kuroshio

The Kuroshio Current has its origin in the northwestern Pacific, flowing northward to the east of Taiwan and the northern part of Luzon Island. As the Kuroshio Current flows northward, it quasi-periodically intrudes (hereafter referred to as Kuroshio intrusion (KI)) into the northern South China Sea (SCS) basin through the Luzon Strait. Despite the complex generation mechanisms of KI, the purpose of this study is to improve our understanding of the effects of KI through the Luzon Strait on the regional atmospheric and weather variations. Long-term multiple satellite observations, including absolute dynamic topography, absolute geostrophic currents, sea surface winds by ASCAT, multi-scale ultra-high resolution sea surface temperature (MURSST) level-four analysis, and research-quality three-hourly TRMM multi-satellite precipitation analysis (TMPA), was used to systematically examine the aforementioned scientific problem. Analysis indicates that the KI is interlinked with the consequential anomalous precipitation off southwestern Taiwan. This anomalous precipitation would lead to ~560 million tons of freshwater influx during each KI event. Subsequently, independent moisture budget analysis suggests that moisture, mainly from vertical advection, is the possible source of the precipitation anomaly. Additionally, a bulk formula analysis was applied to understand how KI can trigger the precipitation anomaly through vertical advection of moisture without causing an evident change in the low-level flows. These new research findings might reconcile the divisiveness on why winds are not showing a synchronous response during the KI and consequential anomalous precipitation events.

scholarly journals Rapid warming of sea surface temperature along the Kuroshio and the China coast in the East China Sea during the 20th century

2021 ◽  
pp. 1-43
Author(s):  
Yoshi N. Sasaki ◽  
Chisato Umeda
Keyword(s):  
20Th Century ◽  
East China Sea ◽  
Sea Surface ◽  
East China ◽  
Model Output ◽  
The East China Sea ◽  
China Sea ◽  
Sst Warming ◽  
The Kuroshio ◽  
China Coast

AbstractIt has been reported that the sea surface temperature (SST) trend of the East China Sea during the 20th century was a couple of times larger than the global mean SST trend. However, the detailed spatial structure of the SST trend in the East China Sea and its mechanism have not been understood. The present study examines the SST trend in the East China Sea from 1901 to 2010 using observational data and a Regional Ocean Modeling System (ROMS) with an eddy-resolving horizontal resolution. A comparison among two observational datasets and the model output reveal that enhanced SST warming occurred along the Kuroshio and along the coast of China over the continental shelf. In both regions, the SST trends were the largest in winter. The heat budget analysis using the model output indicates that the upper layer temperature rises in both regions were induced by the trend of ocean advection, which was balanced to the increasing of surface net heat release. In addition, the rapid SST warming along the Kuroshio was induced by the acceleration of the Kuroshio. Sensitivity experiments revealed that this acceleration was likely caused by the negative wind stress curl anomalies over the North Pacific. In contrast, the enhanced SST warming along the China coast resulted from the ocean circulation change over the continental shelf by local atmospheric forcing.

scholarly journals A global eddying hindcast ocean simulation with OFES2

2020 ◽  
Vol 13 (7) ◽  
pp. 3319-3336 ◽  
Author(s):  
Hideharu Sasaki ◽  
Shinichiro Kida ◽  
Ryo Furue ◽  
Hidenori Aiki ◽  
Nobumasa Komori ◽  
...  
Keyword(s):  
General Circulation ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Tidal Mixing ◽  
Surface Salinity ◽  
Previous Version ◽  
Spatiotemporal Scales ◽  
The Kuroshio

Abstract. A quasi-global eddying ocean hindcast simulation using a new version of our model, called OFES2 (Ocean General Circulation Model for the Earth Simulator version 2), was conducted to overcome several issues with unrealistic properties in its previous version, OFES. This paper describes the model and the simulated oceanic fields in OFES2 compared with OFES and also observed data. OFES2 includes a sea-ice model and a tidal mixing scheme, is forced by a newly created surface atmospheric dataset called JRA55-do, and simulated the oceanic fields from 1958 to 2016. We found several improvements in OFES2 over OFES: smaller biases in the global sea surface temperature and sea surface salinity as well as the water mass properties in the Indonesian and Arabian seas. The time series of the Niño3.4 and Indian Ocean Dipole (IOD) indexes are somewhat better in OFES2 than in OFES. Unlike the previous version, OFES2 reproduces more realistic anomalously low sea surface temperatures during a positive IOD event. One possible cause of these improvements in El Niño and IOD events is the replacement of the atmospheric dataset. On the other hand, several issues remained unrealistic, such as the pathways of the Kuroshio and Gulf Stream and the unrealistic spreading of salty Mediterranean overflow. Given the worldwide use of the previous version and the improvements presented here, the output from OFES2 will be useful in studying various oceanic phenomena with broad spatiotemporal scales.

scholarly journals Observed Warm Filaments from the Kuroshio Associated with Mesoscale Eddies

2020 ◽  
Vol 12 (18) ◽  
pp. 3090
Author(s):  
Qian Shi ◽  
Guihua Wang
Keyword(s):  
High Frequency ◽  
Average Length ◽  
Mesoscale Eddies ◽  
Satellite Observations ◽  
Sea Surface ◽  
Large Temperature ◽  
Anticyclonic Eddies ◽  
The Kuroshio ◽  
Sst Gradient

Based on high resolution satellite observations of sea surface temperature (SST), warm filaments near the Kuroshio around the Luzon Strait were systematically identified. These filaments extend an average length of about 200 km from the Kuroshio. The occurrence and features of the warm filaments are highly associated with both mesoscale eddies and the intensity of the SST gradient of the Kuroshio. Warm filaments are formed by heat advection from the warm Kuroshio into the colder interior Pacific Ocean by anticyclonic eddies (∼58%), cyclonic eddies (∼10%), and the dipole eddies (∼16%). The large temperature gradient near the Batanes Islands may also contribute to the high frequency of warm filaments in their vicinity. This study will help elucidate the role of zonal heat transport associated with the Kuroshio–eddy interaction during filament formation.

Sign in / Sign up

Export Citation Format

Share Document