Plume Flow Research Articles

Intracontinental mantle plume and its implications for the Cretaceous tectonic history of East Asia

A-type granitoids, high-Mg basalts (e.g., picrites), adakitic rocks, basin-and-range-type fault basins, thinning of the North China Craton (NCC), and southwest-to-northeast migration of the adakites and I-type granitoids in southern Korea and southwestern Japan during the Cretaceous are attributed to the passive upwelling of deep asthenospheric mantle or ridge subduction. However, the genesis of these features remains controversial. Furthermore, the lack of ridge subduction during the Cretaceous in recently suggested plate reconstruction models poses a problem because the Cretaceous adakites in southern Korea and southwestern Japan could not have been generated by the subduction of the old Izanagi oceanic plate. Here, we speculate that plume-continent (intracontinental plume-China continent) and subsequent plume-slab (intracontinental plume-subducted Izanagi oceanic plate) interactions generated the various intracontinental magmatic and tectonic activities in eastern China, Korea, and southwestern Japan. We support our proposal using three-dimensional numerical models: 1) An intracontinental mantle plume is dragged into the mantle wedge by corner flow of the mantle wedge, and 2) the resultant channel-like flow of the mantle plume in the mantle wedge apparently migrated from southwest to northeast because of the northeast-to-southwest migration of the East Asian continental blocks with respect to the Izanagi oceanic plate. Our model calculations show that adakites and I-type granitoids can be generated by increased slab-surface temperatures because of the channel-like flow of the mantle plume in the mantle wedge. We also show that the southwest-to-northeast migration of the adakites and I-type granitoids in southern Korea and southwestern Japan can be attributable to the opposite migration of the East Asian continental blocks with respect to the Izanagi oceanic plate. This correlation implies that an intracontinental mantle plume existed in eastern China during the Cretaceous and that the mantle plume was entrained into the mantle wedge as a channel-like flow. An intracontinental mantle plume can explain the adakitic rocks, A-type granitoids, high-Mg basalts, and basin-and-range-type fault basins distributed in eastern China. Thus, the mantle plume and its interaction with the overlying continent and subducting slab through time plausibly explain the Cretaceous tectonic history of East Asia.

Vapor plume oscillation mechanisms in transient keyhole during tandem dual beam fiber laser welding

Vapor plume oscillations are common physical phenomena that have an important influence on the welding process in dual beam laser welding. However, until now, the oscillation mechanisms of vapor plumes remain unclear. This is primarily because mesoscale vapor plume dynamics inside a millimeter-scale, invisible, and time-dependent keyhole are difficult to quantitatively observe. In this paper, based on a developed three-dimensional (3D) comprehensive model, the vapor plume evolutions in a dynamical keyhole are directly simulated in tandem dual beam, short-wavelength laser welding. Combined with the vapor plume behaviors outside the keyhole observed by high-speed imaging, the vapor plume oscillations in dynamical keyholes at different inter-beam distances are the first, to our knowledge, to be quantitatively analyzed. It is found that vapor plume oscillations outside the keyhole mainly result from vapor plume instabilities inside the keyhole. The ejection velocity at the keyhole opening and dynamical behaviors outside the keyhole of a vapor plume both violently oscillate with the same order of magnitude of high frequency (several kHz). Furthermore, the ejection speed at the keyhole opening and ejection area outside the keyhole both decrease as the beam distance increases, while the degree of vapor plume instability first decreases and then increases with increasing beam distance from 0.6 to 1.0 mm. Moreover, the oscillation mechanisms of a vapor plume inside the dynamical keyhole irradiated by dual laser beams are investigated by thoroughly analyzing the vapor plume occurrence and flow process. The vapor plume oscillations in the dynamical keyhole are found to mainly result from violent local evaporations and severe keyhole geometry variations. In short, the quantitative method and these findings can serve as a reference for further understanding of the physical mechanisms in dual beam laser welding and of processing optimizations in industrial applications.

A Mathematical Model for the Multiphase Transport and Reaction Kinetics in a Ladle with Bottom Powder Injection

A computation fluid dynamics-population balance model-simultaneous reaction model (CFD-PBM-SRM) coupled model has been proposed to study the multiphase flow behavior and refining reaction kinetics in a ladle with bottom powder injection, and some new and important phenomena and mechanisms are presented. For the multiphase flow behavior, the effects of bubbly plume flow, powder particle motion, particle-particle collision and growth, particle-bubble collision and adhesion, and powder particle removal into top slag are considered. For the reaction kinetics, the mechanisms of multicomponent simultaneous reactions, including Al, S, Si, Mn, Fe, and O, at the multi-interface, including top slag-liquid steel interface, air-liquid steel interface, powder droplet-liquid steel interface, and bubble-liquid steel interface, are presented, and the effect of sulfur solubility in the powder droplet on the desulfurization is also taken into account. Model validation is carried out using hot tests in a 2-t induction furnace with bottom powder injection. The result shows that the powder particles gradually disperse in the entire furnace; in the vicinity of the bottom slot plugs, the desulfurization product CaS is liquid phase, while in the upper region of the furnace, the desulfurization product CaS is solid phase. The predicted sulfur contents by the present model agree well with the measured data in the 2-t furnace with bottom powder injection.

Effect of Scarfing on Rectangular Nozzle Supersonic Jet Plume Flow Characteristics

An experimental and computational fluid dynamics study is reported of supersonic jets issuing from a high-aspect-ratio rectangular convergent–divergent nozzle with and without a scarfed exit. Schlieren visualization and laser Doppler anemometry measurements captured near-field aerodynamic development of an unheated jet at overexpanded, design, and underexpanded conditions. Reynolds-averaged Navier–Stokes computational fluid dynamics predictions using an eddy viscosity closure (Spalart–Allmaras model) for clean and scarfed geometries were compared with measurements to examine the ability to capture nozzle scarfing effects. The measured plume shape for a scarfed nozzle was strongly affected at overexpanded conditions (a distorted four-lobe shape was observed), whereas a rectangular shape was retained for underexpanded flow although plume bifurcation occurred. The development of the plume shape and the mixing rate was a consequence of the strong vortices that occur with rectangular nozzles, with extra vortices introduced by scarfing. The nozzle exit static pressure changed dramatically when scarfing was added, influencing plume secondary flows and near-field development. The main features of scarfed jet development were predicted qualitatively correctly; the four-lobe overexpanded shape was reproduced but the strength of pressure-driven secondary velocities was overpredicted. The experimental data provided represent a challenging validation test case for computational fluid dynamics studies of three-dimensional supersonic jet plumes with scarfed interaction effects.

The effect of damper leakage and fire size on the performance of smoke control system in high-rise building

The major function of smoke control system is to prevent smoke from penetrating to vertical shaft or stairwell by pressurizing vestibule where is generally located between the vertical shaft and living room. Thus, it is important to calculate the required flow rate of air supply for remaining the pressure difference of 40 ~ 60 Pa between the shaft and vestibule. Heat and mass transfer from fire plume and leaking flows among building structures are representative influence factors on the flow rate. The previous studies, however, focused on calculation of the flow rate of air supply without considering the fire effect and damper leakage. In this study, the effect of damper leakage and fire size on the performance of smoke control system was investigated when considering various parameters, i.e., building size and pressurizing method. The effective damper leakage area was measured in a wind tunnel and used to numerical analysis for parameter study. As the results, in the case of whole floor pressurizing method, the increase rate of the flow rate is about two times than that of the parted floor pressurizing method. Also, the pressure difference steeply decreases at the fire floor whereas it slightly increases at the other floors as the fire size increases.

The Effect of Sudden Permeability Changes in Porous Media Filling Box Flows

We report upon experimental and analytical investigations of filling box flows in non-uniform porous media characterized by a sudden change in permeability. The porous medium consists of two layers separated by a horizontal permeability jump and is initially filled with light ambient fluid. A line source located at the top of the upper layer supplies dense contaminated fluid that falls toward the bottom of the domain. Two configurations are studied, i.e., a low-permeability layer on top of a high-permeability layer and vice versa. In the former scenario, the flow dynamics are qualitatively similar to the case of a uniform porous medium. Thus, the analytical formulation of Sahu and Flynn (J Fluid Mech 782:455–478, 2015) can be adopted to compute the parameters of interest, e.g., the plume volume flux. In the latter scenario, the flow dynamics are significantly different from those of the uniform porous medium case; after reaching the permeability jump, some fraction of the dense plume propagates horizontally as a pair of oppositely directed interfacial gravity currents. Meanwhile, the remaining fraction of the plume flows downward into the lower layer where it accumulates along the bottom boundary in the form of a deepening layer of discharged plume fluid. Depending on the permeability ratio of the upper and lower layers and the source conditions, the gravity currents may become temporarily arrested after traveling some finite horizontal length. An analytical prediction for this so-called run-out length is derived, motivated, in part, by the immiscible analysis of Goda and Sato (J Fluid Mech 673:60–79, 2011). Finally, a prediction of the filling box time, consisting of the time required to fill the control volume up to the point of contaminated fluid overflow, is made. These predictions are compared with analog experimental measurements. Generally positive agreement is found when the higher-permeability layer is located below the lower-permeability layer. In the opposite circumstance, the agreement is conditional. If the run-out length of the gravity current is less than the horizontal dimensions of the control volume (or tank in case of the experiments), the agreement is good. By contrast, when the run-out length is large, comparatively poor agreement may be realized: In spite of the higher density of the contaminated fluid, it may occupy the entirety of the upper layer before filling the lower layer.

Plume‐ridge interaction via melt channelization at Galápagos and other near‐ridge hotspot provinces

AbstractThe interaction of mantle plume driven flow with upwelling flow due to a nearby mid‐ocean ridge occurs for many mantle plumes including Galápagos and Iceland. This interaction is typified by trace element and isotopic signatures demonstrating the “contamination” of normal ridge composition by relatively enriched plume material. However, another common signature of plume‐ridge interaction is volcanic lineaments linking ridges and nearby plumes, perhaps most conspicuously the Wolf‐Darwin lineament (WDL) at Galápagos and the Rodrigues Ridge (RR) at La Réunion. These enigmatic features remain unexplained. Plume‐ridge interaction is commonly modeled in terms of interaction between solid‐state plume flow and divergent ridge flow, but such models do not likely lead to the kind of solid‐state flow channelization that might explain narrow features such as the WDL and RR. Likewise, models involving tapping of anomalously hot and/or fertile asthenosphere between the plume and ridge due to lithospheric faulting appear to be inconsistent with a variety of evidence. We propose an alternative model in which the lineaments are the surface expressions of localized melt channels in the asthenosphere formed due to instabilities in a two‐phase partially molten system. A thermodynamic analysis shows that given the magma fluxes inferred to be associated with structures such as WDL and RR, these melt channels can be maintained over plume‐ridge distances up to ∼1000 km. These results suggest that plume‐ridge interaction in general, possibly including transport of plume‐derived material along ridge axes (e.g., Iceland), may involve transport in high‐melt‐fraction channels, as opposed to just solid‐state mantle flow.

PIV and LIF study of flow and thermal fields of twine plumes in water

Flow and thermal fields of a pair of plane plumes in water are investigated by means of PIV and LIF experiments. The plumes are generated from thermal line sources, which are made out of electrically heated cylinders with a diameter of D = 1.21 mm. A cylinder-to-cylinder distance was 17.9 D . Either continuous or pulsating heating were used with the same heating input power. Because the cylinder-to-cylinder distance is moderately small, deflections of plumes from a vertical direction occur and the plumes are inclined together. This behavior is caused by a confined entrainment from a space between the both plumes. For a continuous heating, low frequency oscillations were identified and the natural frequency was evaluated as 0.5 Hz. Based on this finding, pulsating heating was used at the subharmonic frequency of 0.25 Hz. The maximum time-mean velocity magnitude at the continuous and pulsating heating were commensurable, approximately 0.007 m/s. On the other hand, pulsating heating achieves by 36 % higher velocity peaks. A very strong velocity oscillations were generated by pulsating heating at the distance approximately 8.3 D above the cylinders, where the velocity maxima oscillate along the time-mean value of 0.0057 m/s from −30% to +70 %. Temperature fields reasonably agree with this findings, despite a relatively fast equalization of the temperature field was concluded. The results demonstrate enhancement effects of pulsations in flow/thermal fields.

Isotopically enriched N‐MORB: A new geochemical signature of off‐axis plume‐ridge interaction—A case study at 50°28′E, Southwest Indian Ridge

AbstractInteraction between the Southwest Indian Ridge (46°E and 52°20′E) and Crozet hotspot has been proposed by geophysical studies but remains controversial mostly due to the lack of E‐MORB (enriched mid‐ocean ridge basalts). Forty‐seven new samples collected from this region, including 15 from segment 27 centered at 50°28′E with a 10 km thick crust, are all N‐MORB (normal MORB) and can be classified into two groups: a high‐Al group only at 50°28′E and a Main group widespread. The former, with higher Al2O3 and lower TiO2 and SiO2, have slightly enriched Sr‐Nd‐Hf‐Pb isotopic compositions. We propose that their major and trace elemental signatures were modified by reaction with primitive cumulate in the crust, whereas the enriched isotopic compositions indicate the contribution of Crozet plume materials. During upslope flow of the Crozet plume to the ridge, decompression melting would occur along the path, which would deplete the plume in incompatible elements but not significantly change the isotopic compositions. Thus, when they finally reach the ridge, the depleted residue would remelt due to further decompression at MOR and produce isotopically enriched N‐MORB at segment 27. Isotopically enriched N‐MORB are known elsewhere, mostly at slower‐spreading ridges possibly influenced by plumes with large plume‐ridge distances. In particular, the constant Nd isotopic compositions with decreasing (La/Sm)N ratios for off‐axis magmatism between the Réunion hotspot toward the CIR perfectly match such a plume‐ridge interaction model. Therefore, aside from E‐MORB, isotopically enriched N‐MORB can also be considered as the geochemical signature for off‐axis plume‐ridge interaction.

基于红外技术的液体火箭发动机尾焰流场测量研究

基于红外技术的液体火箭发动机尾焰流场测量研究

Measurements and Visualization of the Fluid Field of the Plume from an Animal Housing Ventilation Fan

Various dispersion models have been developed to simulate the fate and transport of air emissions from animal housing systems to meet the increasing need for knowledge in this area. However, the accuracy of the models may be challenged due to the unknown plume rise and plume shape. This paper reports a combination of theoretical and field study of the plum rise and shape of air flow from a ventilation fan commonly used in mechanically ventilated animal houses. The theoretical modeling of the plume shape was conducted using a commercial Computational Fluid Dynamics (CFD) package named FloEFD; the field measurements of the plume field was conducted using five 3D ultrasonic anemometers to simultaneously measure the air flow in the plume at various locations (four heights and five downwind distances). The TECPLOT package was used to visualize the plume flow field based upon anemometer measurements. While the plume shapes were found to be left-shifted by the CFD model and TECPLOT visualization, the magnitudes of the 3D wind velocities from field measurement were found to be significantly larger than those from CFD model. The plume field measurements indicated that the plume of a 0.6 m (24-inch) ventilation fan had a depth about 9 m, a width about ±6 m, and a rise (lifting) beyond the highest measurement point, 4.88 m (16 ft).

基于红外技术的液体火箭发动机尾焰流场测量研究

基于红外技术的液体火箭发动机尾焰流场测量研究

Three-Dimensional Numerical Analysis of LOX/Kerosene Engine Exhaust Plume Flow Field Characteristics

Aiming at calculating and studying the flow field characteristics of engine exhaust plume and comparative analyzing the effects of different chemical reaction mechanisms on the engine exhaust plume flow field characteristics, a method considering fully the combustion state influence is put forward, which is applied to exhaust plume flow field calculation of multinozzle engine. On this basis, a three-dimensional numerical analysis of the effects of different chemical reaction mechanisms on LOX/kerosene engine exhaust plume flow field characteristics was carried out. It is found that multistep chemical reaction can accurately describe the combustion process in the LOX/kerosene engine, the average chamber pressure from the calculation is 4.63% greater than that of the test, and the average chamber temperature from the calculation is 3.34% greater than that from the thermodynamic calculation. The exhaust plumes of single nozzle and double nozzle calculated using the global chemical reaction are longer than those using the multistep chemical reaction; the highest temperature and the highest velocity on the plume axis calculated using the former are greater than that using the latter. The important influence of chemical reaction mechanism must be considered in the study of the fixing structure of double nozzle engine on the rocket body.

Observations of inner shelf cross-shore surface material transport adjacent to a coastal inlet in the northern Gulf of Mexico

Motivated by the Deepwater Horizon oil spill, the Surfzone and Coastal Oil Pathways Experiment obtained Acoustic Doppler Current Profiler (ADCP) Eulerian and GPS-drifter based Lagrangian “surface” (<1m) flow observations in the northern Gulf of Mexico to describe the influence of small-scale river plumes on surface material transport pathways in the nearshore. Lagrangian paths are qualitatively similar to surface pathlines derived from non-traditional, near-surface ADCP velocities, but both differ significantly from depth-averaged subsurface pathlines. Near-surface currents are linearly correlated with wind velocities (r =0.76 in the alongshore and r =0.85 in the cross-shore) at the 95% confidence level, and are 4–7 times larger than theoretical estimates of wind and wave-driven surface flow in an un-stratified water column. Differences in near-surface flow are attributed to the presence of a buoyant river plume forced by winds from passing extratropical storms. Plume boundary fronts induce a horizontal velocity gradient where drifters deployed outside of the plume in oceanic water routinely converge, slow, and are re-directed. When the plume flows west parallel to the beach, the seaward plume boundary front acts as a coastal barrier that prevents 100% of oceanic drifters from beaching within 27km of the inlet. As a result, small-scale, wind-driven river plumes in the northern Gulf of Mexico act as coastal barriers that prevent offshore surface pollution from washing ashore west of river inlets.

Numerical study on rarefied unsteady jet flow expanding into vacuum using the Gas-Kinetic Unified Algorithm

The unsteady process of rarefied jet flows expanding into a vacuum is numerically solved by the Gas-Kinetic Unified Algorithm (GKUA) based on the Boltzmann model equations. The discrete velocity ordinate method (DVOM) is adopted to discretize the velocity space of the molecular velocity distribution function, while the corresponding numerical integral technique is developed to evaluate macroscopic flow variables, including number density, flow velocity, temperature and so on. The time-explicit finite difference scheme is constructed to capture the unsteady evolution of the discrete velocity distribution functions at each DVO point by using the unsteady time-splitting method. The multi-block docking grid technique is designed for different regions of flow field in physical space with self-adaptive adjustment. Then, the supersonic planar jet flows with the wide range of Knudsen numbers, from 100 to 0.1, are solved numerically and discussed, including startup to steady state and shutting down. The GKUA results of free-molecule jet flows are analyzed and compared with the Maxwellian analytical solutions for collisionless plume flows, in which good agreement shows the validity and accuracy of the present numerical method. When taking the collision effect into account, the unsteady jet flows with different Knudsen numbers are computed by the present GKUA method. It is shown that the collision term of the Boltzmann model equation plays an important role in this rarefied gas diffusion into the back flow when Kn ≤ 10. However, the colliding relaxation term have a little influence on the kernel region in the startup process for Kn ≥ 0.1. In general, the convective transport term of the Boltzmann model equation dominates the kernel region of the jet flow during the unsteady process of gas expanding into a vacuum. The numerical experience indicates that the present GKUA can provide a vital tool for solving unsteady flow problems covering various flow regimes by directly tracing the time evolution of the Boltzmann-type velocity distribution function.

Propagating buoyant mantle upwelling on the Reykjanes Ridge

Crustal features of the Reykjanes Ridge have been attributed to mantle plume flow radiating outward from the Iceland hotspot. This model requires very rapid mantle upwelling and a “rheological boundary” at the solidus to deflect plume material laterally and prevent extreme melting above the plume stem. Here we propose an alternative explanation in which shallow buoyant mantle upwelling instabilities propagate along axis to form the crustal features of the ridge and flanks. As only the locus of buoyant upwelling propagates this mechanism removes the need for rapid mantle plume flow. Based on new geophysical mapping we show that a persistent sub-axial low viscosity channel supporting buoyant mantle upwelling can explain the current oblique geometry of the ridge as a reestablishment of its original configuration following an abrupt change in opening direction. This mechanism further explains the replacement of ridge-orthogonal crustal segmentation with V-shaped crustal ridges and troughs. Our findings indicate that crustal features of the Reykjanes Ridge and flanks are formed by shallow buoyant mantle instabilities, fundamentally like at other slow spreading ridges, and need not reflect deep mantle plume flow.

Acoustic measurements of vertical velocity and temperature fluctuations of a hydrothermal plume with comparisons to large eddy simulations

The acoustic scintillation method is used to study the hydrothermal plume of Dante within the Main Endeavour vent field (MEF) at the Endeavour segment of the Juan de Fuca Ridge. Forty days of vertical velocity and temperature fluctuations were obtained from the rising plume above the Dante edifice in an environment where the flow is dominated by strong (5cm/s) semi-diurnal tidal currents and a northerly mean residual current (3cm/s). These acoustic measurements provide a window on deep-sea hydrothermal plume dynamics in strong oscillatory cross flows. A large eddy simulation, parameterized with anisotropic mixing coefficients, taking into account ambient stratification and time-dependent background flows and calibrated by the acoustic measurements, yields insight into turbulent processes, entrainment, plume bending, rise height, and, inferentially, mound heat flux. The turbulent dissipation rates for kinetic energy (ε) and thermal variance (εθ) is approximated by computing the Reynolds averaged sub-grid scale turbulent production from shear and buoyancy (ε = P-B) and from temperature fluxes (εθ = Pθ), respectively, which are needed to compare to the acoustic derived turbulence levels. A new cabled observatory reciprocal acoustic scintillation system on the NEPTUNE observatory that will allow real time measurements of mean and turbulent flow of a hydrothermal plume will also be introduced.

Wind relaxation and a coastal buoyant plume north of Pt. Conception, CA: Observations, simulations, and scalings

AbstractIn upwelling regions, wind relaxations lead to poleward propagating warm water plumes that are important to coastal ecosystems. The coastal ocean response to wind relaxation around Pt. Conception, CA is simulated with a Regional Ocean Model (ROMS) forced by realistic surface and lateral boundary conditions including tidal processes. The model reproduces well the statistics of observed subtidal water column temperature and velocity at both outer and inner‐shelf mooring locations throughout the study. A poleward‐propagating plume of Southern California Bight water that increases shelf water temperatures by 5°C is also reproduced. Modeled plume propagation speed, spatial scales, and flow structure are consistent with a theoretical scaling for coastal buoyant plumes with both surface‐trapped and slope‐controlled dynamics. Plume momentum balances are distinct between the offshore (&gt;30 m depth) region where the plume is surface‐trapped, and onshore of the 30 m isobath (within 5 km from shore) where the plume water mass extends to the bottom and is slope controlled. In the onshore region, bottom stress is important in the alongshore momentum equation and generates vertical vorticity that is an order of magnitude larger than the vorticity in the plume core. Numerical experiments without tidal forcing show that modeled surface temperatures are biased 0.5°C high, potentially affecting plume propagation distance and persistence.

Radium isotopes assess water mixing processes and its application in the Zhujiang River estuary

Radium (Ra) isotopes are useful for tracing water mass transport and examining estuarine hydrological dynamics. In this study, several hydrological parameters, nutrients, chlorophyll-a (chl-a), suspended particulate matter (SPM) and Ra isotopes (223Ra, 224Ra and 226Ra) of surface waters of the Zhujiang (Pearl) River estuary (ZRE) were measured. This was done for both winter (December) and summer (July) seasons, to quantitatively understand the seasonal characteristics of river plume flow rate and trajectories, as well as the ecological response. The results show that Ra concentrations in summer were higher than in winter, especially 224Ra (about 2–5 times higher). The spatial distribution of three Ra isotopes and relative Ra water ages indicated that river water mainly flushed out of ZRE through the western side in winter, where the water transport was about 5 days faster than in the eastern zone. In summer, diluted river water expended to the east side, resulting in fairly similar water ages for both sides of the river mouth. Although nutrients were higher during the summer season, lower chl-a concentrations indicated that reduced primary production might be caused by high SPM (low light penetration). The results obtained from this study will provide knowledge needed for effectively developing and managing the ZRE.

Geochemical evidence of the indirect pathway of terrestrial particulate material transport to the Okinawa Trough

The major source of particulate matter in the East China Sea (ECS) is the Changjiang (Yangtze) River. Sediment types, the geochemical indices of terrigenous and biogenic inputs (TOC, CaCO3 and Sc), and biomarker indices such as the carbon preference index (CPI) of long-chain n-alkanes and the cinnamyl/vanillyl ratio (C/V) in surface sediments, all reveal that the influence of terrestrial material initially declines away from the mouth of the Changjiang River across the ECS continental shelf. However, the influence then strengthens from the middle ECS shelf toward the continental slope and the Okinawa Trough, because when the northeast winds prevail from September to April, the Changjiang River plume flows southwestward along the coast of China. Part of this flow turns eastward in the northern Taiwan Strait, and then joins the northeastwardly flowing Kuroshio to reach the Okinawa Trough. As the central ECS is bypassed, the sediments accumulated there are geologically older, carbonate-rich and organic-poor than those found off the coast of China and in the Okinawa Trough.Between June and August, when southwest winds prevail, the Changjiang plume generally flows northeastward. Yet, strong cyclonic currents that are generated by typhoons that pass through the ECS move the suspended particulates and the resuspended sediments southwestward from the coast of China. The turbid water then turns toward Taiwan in the northern Taiwan Strait and joins the Kuroshio, before reaching the Okinawa Trough. Again, young sediments are transported to the Okinawa Trough without passing through the central ECS.