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The fuel-air mixing is of paramount importance in hypersonic air-breathing vehicles, and its performance is closely related to the fuel injection angle. This article presents an investigation into the influence of the injection angles on the flow and mixing processes in a supersonic combustor at low Mach supersonic inflow. Detailed flow characteristics are compared and analyzed, with a focus on instantaneous and average flows. Besides, several significant mixing parameters are thoroughly depicted. Results show that, in contrast to transverse injection, relatively strong fuel fluctuation is presented on the leeward side in comparison to the windward side in the near field for the inclined injection. Furthermore, the counter-rotating vortex pairs (CVP) are constricted by the inclination of the injection, giving rise to a decrease in jet-cavity interaction. Although inclined injection exhibits favorable performance in backpressure resistance at low Mach supersonic crossflow, it presents a greater challenge in terms of ignition, thus necessitating meticulous design considerations. [ABSTRACT FROM AUTHOR]

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In this study, direct numerical simulation of the particle dispersion and turbulence modulation in a sonic transverse jet injected into a supersonic cross-flow with a Mach number of 2 was carried out with the Eulerian–Lagrangian point-particle method. One single-phase case and two particle-laden cases with different particle diameters were simulated. The jet and particle trajectories, the dispersion characteristics of particles, and the modulation effect of particles on the flow were investigated systematically. It was found that large particles primarily accumulate around shear layer structures situated on the windward side of the jet trajectory. In contrast, small particles exhibit radial transport, accessing both upstream and downstream recirculation zones. Moreover, small particles disperse extensively within the boundary layer and large-scale shear layers, evidently influenced by the streamwise vortices. The particles increase the mean wall-normal velocity near the wall in the wake region of the transverse jet, while reducing the mean streamwise and wall-normal velocities in outer regions. Particles significantly alter the flow velocity adjacent to shock fronts. In particular, the turbulent fluctuations near the windward barrel shock and bow shock are reduced, while those around the leeward barrel shock are increased. An upward displacement of the bow shock in the wall-normal direction is also observed due to particles. In the regions away from the shocks, small particles tend to amplify the Reynolds stress, while large particles attenuate the turbulent kinetic energy. [ABSTRACT FROM AUTHOR]

Existing methods for improving the mixing of jets in supersonic and hypersonic crossflows focus on the addition of obstructions such as cavities, steps, and wedges, which serve to create re-circulation zones and increase the residence time of the fuel–air mixing. Recent literature has shown that, under certain conditions, the jet stream can pass into the boundary layer upstream of the jet, where low-velocity high-residence time mixing can occur. To develop a fundamental understanding of the entrainment mechanism of the jet fluid to the forward boundary layer (J-FBL), an implicit large eddy simulation is employed for a Mach 5 hypersonic crossflow and a momentum flux ratio of 5.18 between the jet and crossflow. It is observed that the jet fluid entrainment occurs through a thin channel stemming from the barrel shock, close to the bow shock and near-wall shear layer. By measuring the flow through this channel, it is shown that the J-FBL entrainment flux varies over time. It is observed that the entrainment channel from the jet to the boundary layer varies in size, shape, and direction with the deformation of the barrel shock by the formation and shedding of the barrel shock shear layer (BSL) vortices. From this, it is determined that the driving mechanism for the J-FBL entrainment is the size and shape of the barrel shock. It is concluded that any flow control schemes that alter the shape of the barrel shock may be employed for utilizing the J-FBL entrainment phenomena and thus near-wall mixing. [ABSTRACT FROM AUTHOR]

The flow-induced vibrations (FIVs) of staggered two-degree-of-freedom cylinders with a constant streamwise offset (L/D = 2, L is the streamwise spacing between the cylinders of diameter D) and varying cross-stream offset (0 ≤ S/D ≤ 5, S is the cross-stream spacing) were numerically simulated. The effects of S/D on the in-line and cross-flow vibrations, flow fields, distributions of the surface pressures, and the energy properties were comprehensively investigated to study the characteristics of the FIVs. The upstream cylinder primarily experiences vortex-induced vibrations (VIVs), while distinct FIVs of the downstream cylinder occur when S/D ranges from 0 to 3, and the flow characteristics vary with the reduced velocity (Vr) and S/D. When Vr = 3, vortex pairs along with reverse-flow reattachment are observed within the gap zone at small S/D. The pressures on the downstream cylinder become asymmetric due to the vortex strong interactions. When Vr = 7 and 11, a merging vortex emerges and moves closer to the rear surface of the downstream cylinder with increasing S/D, which increases negative pressure on the lower part of the downstream cylinder, further influencing the promoting effect of the merging vortex on structural vibrations. Moreover, when S/D ≥ 3, the effects of the upstream cylinder on the downstream cylinder diminish. Both cylinders exhibit identical vibrations and wake patterns, and the mean power distribution on the downstream cylinder becomes symmetrical with a magnitude similar to that of the upstream cylinder, which can be considered as two independent cylinders undergoing VIVs. [ABSTRACT FROM AUTHOR]

Numerical investigations were conducted to analyze the coupling effects of pulsed H2 jets and nanosecond-pulsed actuation (NS-SDBD) in a supersonic crossflow. The FVM was employed to solve the multi-component 2D URANS equations with the SST k-omega turbulence model, while H2-air combustion was described using a seven species–seven reactions chain reaction model, and the plasma thermal effect was represented by a phenomenological model. The backward-facing step flows with an inlet Mach number of 2.5 and a pulsed jet frequency of 10 kHz under different actuation conditions were simulated. The combustion enhancement mechanism under an actuation frequency of 20 kHz was analyzed. Research indicates that compression waves induced by NS-SDBD enhance H2-air mixing and facilitate temperature transport as the flow progresses. This progress is significantly associated with the flow structures generated by pulsed jets. Under this condition, the fuel utilization rate in the flow field increased by 61.2%, the total pressure recovery coefficient increased by 5.34%, and the outlet total temperature slightly increased even with a 50% reduction in fuel flow rate. Comparative analysis of different actuation cases demonstrates that evenly distributed actuation within the jet cycle yields better effects. The innovation of this study lies in proposing and exploring a potential method to address inadequate combustion under high-speed inflow conditions, which couples NS-SDBD with pulsed hydrogen jets. [ABSTRACT FROM AUTHOR]

The article presents a novel framework for active flow control on airfoils using a transformer-based policy improvement operator, showcasing improved aerodynamic performance across various airfoil configurations. The study demonstrates gradual enhancement in policy learning and aerodynamic performance through active flow control, extending to aerodynamic shape optimization with significant improvements in performance. The research explores active flow control policies using reinforcement learning and transformer architecture for various airfoils, emphasizing the potential of in-context learning for efficient policy improvement without extensive training. Recent advancements in applying deep reinforcement learning for flow control in fluid dynamics scenarios are discussed, including multi-agent reinforcement learning for effective control and transfer training of policy networks to accelerate and improve deep reinforcement learning-based active flow control. [Extracted from the article]

The article in the Journal of Fluid Mechanics delves into a parametric study and scaling of a supersonic jet manipulated by a minijet, focusing on control parameters like mass flow rate ratio and diameter ratio. The study reveals that the minijet can induce coherent structures in the jet, enhancing mixing, and proposes a scaling law based on the penetration depth of the minijet. Additionally, the document from CRC Press covers various studies on active flow control, shock pattern transformation in supersonic jets, and fluidic flow control effectors for flight control, offering valuable insights into aerospace engineering. [Extracted from the article]

The article delves into the Eulerian–Lagrangian direct numerical simulation of turbulence modulation in a compressible multiphase transverse jet. It examines how particles disperse and affect flow in a sonic transverse jet injected into a supersonic cross-flow, with large particles accumulating around shear layers and small particles exhibiting radial transport. The research aims to enhance understanding of compressible gas–solid two-phase transverse jets and their interactions with high-speed flows, shedding light on practical engine design considerations. [Extracted from the article]

The article explores an experimental study on data-driven active control of a thin elliptical cylinder experiencing transverse flow-induced vibrations. By implementing axial flapping motions using Bayesian optimization, researchers were able to maximize vibration amplitudes and uncover two new synchronization regimes not previously reported. The findings have implications for energy extraction from water sources, shedding light on the coupling between vortex-induced vibration and galloping-like movement-induced instability. The study delves into the effects of axial rotation on wake-body synchronization and vibration amplitudes, identifying distinct regimes and analyzing control parameters for optimal performance. [Extracted from the article]

This study investigates the impact of a rotating tube on the flow characteristics within a tube bank consisting of nine cylinders arranged in an in-line configuration, with a pitch-to-diameter ratio of 1.44, using both experimental and numerical approaches. Experiments are performed in a subsonic wind tunnel to measure pressure distributions at various azimuthal angles along the tubes, using a multi-channel differential pressure system. Drag forces are determined via a wire-strain gauge balance. Numerical simulations are conducted using ANSYS Fluent, employing the URANS-based Shear-Stress Transport (SST) k–ω model, to replicate turbulent cross-flow at two values of Reynolds numbers Re=0.712×105 and Re=1.42×105. This study explores the effect of a tube rotation within the array on flow separation angles, pressure distributions and vortex shedding in the wake region, focusing on the effects of different positions of the rotating tube on the flow characteristics of the surrounding tubes. Numerical results closely match the experimental data, demonstrating that the rotational motion significantly mitigates flow separation and reduces drag forces on adjacent tubes. Additionally, the position of the rotating tube within the array plays a critical role in optimizing the fluid forces and pressure distribution, offering enhanced control over the flow within tube banks. [ABSTRACT FROM AUTHOR]

The article delves into the flow structures and combustion regimes in an axisymmetric scramjet combustor with high Reynolds numbers. Through experimental and numerical methods, the study uncovers how combustion alters vorticity in the flow field, with shockwaves and turbulent flows playing key roles. Combustion-induced heat release impacts vorticity upstream, in the cavity, and downstream, influencing flow dynamics and turbulence intensity. The findings shed light on the intricate interplay between combustion and flow structures in high-speed airbreathing engines, particularly at Mach-6 flight conditions. [Extracted from the article]

This study experimentally investigates the flow-induced vibration (FIV) of a flexibly mounted triangular prism with two degrees of freedom (DoF), capable of oscillating in its first two vibrational modes in the crossflow direction. The experiments were conducted by varying the angle of attack (α) in the range of 0°–60° and eigenfrequency ratio (R), which is the ratio between the second and first eigenfrequency, from R = 1.5 to 3. For α = 0° and 15°, no significant oscillations were observed. At α = 30 ° , both vortex-induced vibration (VIV) and galloping-type response were detected. For higher angles of attack, α = 45° and 60°, a pure galloping type response was identified. Hydrogen bubble flow visualization was employed to analyze the vortex-dominated wake and to discern the nature of the FIV response—whether it was VIV or galloping. Although the prism was free to oscillate in both its first and second modes, only the first mode contributed to the FIV response at α = 45° and 60°, where galloping was dominant. The FIV response remained primarily influenced by the first mode, except when mode two was externally excited, resulting in pronounced hard mode-two galloping behavior. Because mode one predominantly drives the system's overall FIV response, variations in the eigenfrequency ratio had minimal impact on the system's overall FIV behavior. [ABSTRACT FROM AUTHOR]

The early evolution of the traveling crossflow instability on a flat plate with a sweep angle of 75° is experimentally investigated. The experiments are conducted in a Mach 6 quiet wind tunnel through the nano-tracer-based planar laser scattering (NPLS) technique under the unit Reynolds number of 3.45 × 106 m−1. The spanwise and streamwise structures of the traveling crossflow waves are captured, and the wavelength and frequency characteristics of the traveling crossflow waves are quantitatively analyzed based on wavelet analysis. The results show that with the increase in z-coordinate and x-coordinate, the distribution range of the traveling crossflow waves in y-direction expands, the amplitude of disturbance waves increases, and saturated crossflow wave structures appear gradually. The wavelength of the crossflow waves is about 24 mm and does not change much in different positions. In addition, the propagation velocity of the crossflow waves along the x-direction at the position of x = 130 mm and z = 60 mm is quantitatively calculated, U = 303 m/s. Thus, the characteristic frequency of the crossflow waves obtained from the NPLS image is f ≈ 12 kHz, close to 9.57 kHz measured by Kulite at the same position. [ABSTRACT FROM AUTHOR]

The analysis of the fluid cross-flow characteristics in partially filled cavities is essential for characterizing the fluid flow behaviors in deep marine carbonate reservoirs. Thus, it is vital for the effective development of crude oil in deep marine carbonate reservoirs. This study presents mathematical models for portraying the fluid cross-flow characteristics in partially filled cavities, considering the effects of gravity, cavity filling degree, and storability ratio. By solving the models using the Laplace transformation and Stehfest numerical inversion methods, pressure transient analysis, and rate transient analysis can be performed on the reservoir, resulting in the evaluation of the dimensionless pressure, dimensionless cross-flow rate, and dimensionless cumulative cross-flow rate in a cavity. The available experimental data adequately validate the proposed models. Moreover, based on the derived model, parameter sensitivity analysis is conducted. Based on the results, the cross-flow characteristics are significantly affected by fluid and cavity parameters. Additionally, as the thickness-to-radius ratio of the cavity decreases, the radial flow becomes pronounced, leading to a more complicated cross-flow process. The derived model not only assists in understanding and predicting the cross-flow characteristics in partially filled cavities in deep marine carbonate reservoirs but also provides guidance for crude oil exploitation. [ABSTRACT FROM AUTHOR]

In this study, the hydrodynamics and thermal behavior in the crossflow of air passing over hybrid tubes in the staggered configuration were numerically investigated. CFD (Computational Fluid Dynamics) study were conducted with the help of the ANSYS Fluent program. In the study, 12 different tube bundle models were created with a combination of circular and wing-shaped tubes. The wing-shaped tubes were placed in the tube bundle at different attack angles (θ: 0° and 180°). Reynolds numbers in the range of 4000 ≤ Re ≤ 12,000 were used. To observe the effects of hybrid tubes and Reynolds numbers on thermal and flow fields, velocity, pressure, and temperature contours were acquired. According to the findings, Nusselt number (Nu) and performance criteria (PC) increased, and friction factor (f) decreased with increasing Re for all tube bundle models. The friction factor of hybrid tube bundles was higher than wing-shaped tube bundles but considerably lower than circular tube bundles. Among the hybrid models, the best heat transfer was obtained in Model 6, the lowest friction factor in Model 11, and the best PC in Model 4. Also, three different stacked ensemble models were created to predict Nu, f, and PC values for CFD analysis. These models are the ensemble of XGBoosts, the ensemble of DNNs, and the ensemble of DNN, XGBoost, and RF. This study revealed that ensemble of XGBoosts is more beneficial than the other in the CFD analysis. [ABSTRACT FROM AUTHOR]

This study examines the variations in wake structures and fluid forces around a cluster of five square cylinders. The cylinders in the cluster are arranged such that a larger cylinder (the main cylinder) is surrounded by four similar but small-sized cylinders, which are very common in marine risers and axial pipe shrouds. The analysis uses an in-house developed code based on the lattice Boltzmann method. The gap spacing (g*) between the main and the surrounding cylinders varies from 0 to 10 while maintaining a fixed Reynolds number (Re) of 200. The accuracy and consistency of the code are first tested through simulations that examine the flow behind a single cylinder, revealing strong concurrence with the existing data. In the next step, the flow characteristics of the pentad arrangement are analyzed. Five diverse flow modes, including the extended single bluff body flow, stable symmetric flow, chaotic irregular shedding, antiphase symmetric flow, and modulated periodic flow, are observed depending on the gap distances. It is found that the small cylinders in the downstream position from the primary cylinder experience a negative mean drag at narrow gaps. In contrast, those at the upstream position are subjected to a positive drag force regardless of the gap spacing. The main cylinder has a higher drag coefficient compared to other cylinders for all gap spacing cases. The shedding frequencies appear similar for upstream and downstream smaller-size cylinders at higher spacing values, while the shedding frequencies for the main cylinder significantly deviate from the surrounding small cylinders. [ABSTRACT FROM AUTHOR]

We consider heat or mass transport from a circular cylinder under a uniform crossflow at small Reynolds numbers, $\mathrm{Re}\ll 1$. This problem has been thwarted in the past by limitations inherent in the classical analyses of the singular flow problem, which have used asymptotic expansions in inverse powers of $\log \mathrm{Re}$. We here make use of the hybrid approximation of Kropinski, Ward & Keller [(1995) SIAM J. Appl. Math. 55 , 1484], based upon a robust asymptotic expansion in powers of $\mathrm{Re}$. In that approximation, the "inner" streamfunction is provided by the product of a pre-factor $S$ , a slowly varying function of $\mathrm{Re}$ , with a $\mathrm{Re}$ -independent "canonical" solution of a simple mathematical form. The pre-factor, in turn, is determined as an implicit function of $\log \mathrm{Re}$ via asymptotic matching with a numerical solution of the nonlinear single-scaled "outer" problem, where the cylinder appears as a point singularity. We exploit the hybrid approximation to analyse the transport problem in the limit of large Péclet number, $\mathrm{Pe}\gg 1$. In that limit, transport is restricted to a narrow boundary layer about the cylinder surface – a province contained within the inner region of the flow problem. With $S$ appearing as a parameter, a similarity solution is readily constructed for the boundary-layer problem. It provides the Nusselt number as $0.5799(S\,\mathrm{Pe})^{1/3}$. This asymptotic prediction is in remarkably close agreement with that of the numerical solution of the exact problem [Dennis, Hudson & Smith (1968) Phys. Fluids 11 , 933] even for moderate $\mathrm{Re}$ -values. [ABSTRACT FROM AUTHOR]

The unsteady three-dimensional flow interactions in the near field of square and circular jets issued normally to a crossflow were predicted by direct numerical simulations, aiming to investigate the effect of the nozzle cross-section on the vortical structures formed in this region. The analysis focuses on jets in crossflow with moderate Reynolds numbers ( R e j = 200 and R e j = 300 ) based on the jet velocity the characteristic length of the nozzle and low jet-to-cross-flow velocity ratios, 0.25 ≤ R ≤ 1.4 , where the jets are absolutely unstable. In this regime, the flow becomes periodic and laminar, and three distinct wake flow configurations were identified: (1) symmetric shedding of hairpin vortices at R e j = 200 ; (2) the formation of toroidal vortices as the legs of hairpin vortices merge and the vortices roll up at R e j = 300 and R ≤ 0.67 ; (3) asymmetric shedding of hairpin vortices in the square jet at R e j = 300 and R ≥ 0.9 , where higher-frequency hairpin vortex shedding combines with a low-frequency spanwise oscillation in the counter-rotating vortex pair. The dynamics of each of these flow states were analyzed. Power spectral density plots show a measurable increase in the shedding frequencies in R e j = 300 jets with R, and that these frequencies are consistently larger in circular jets. [ABSTRACT FROM AUTHOR]

The article from the Journal of Fluid Mechanics delves into the flow dynamics around rectangular cylinders at different angles of incidence and the impact of acoustic perturbations on flow instabilities. The research demonstrates that acoustic perturbations can induce resonant conditions, leading to specific shedding patterns and enhancing the streamwise length of the cylinder. By combining numerical and experimental approaches, the study sheds light on the intricate relationship between flow patterns and acoustic resonance, emphasizing the significance of incidence angle in shaping the wake structure of the cylinder. The document presents a series of studies on fluid dynamics, focusing on vortex structures, energy budgets, flow-induced noise, and vibrations in various geometric configurations, utilizing a combination of numerical simulations and experimental methods to analyze these complex interactions. [Extracted from the article]

The present work reports a computational analysis of gaseous bubble bypass through the liquid–liquid interface in the presence of horizontal crossflow. The volume of fluid methodology is employed to carry out the simulations using multiphaseInterFoam solver from the open-source package OpenFOAM. The immiscible liquids are considered as viscous and Newtonian. Efforts are made to elucidate the bubble penetration and subsequent entrainment of liquid lamella within the lighter phase. Furthermore, the bubble passage phenomenon is delineated by considering different bubble sizes, D (2.5–7.5 mm). The entrained lamella retracts early in the presence of crossflow. Reynolds number (R e f) is employed to specify the strength of crossflow. The pattern of vertical as well as horizontal shifts of bubble is predicted when it is traversing from the heavier to the lighter phase. The vertical and horizontal shifts of a same-sized bubble progressively reduce and increase, respectively, with the rise of crossflow strength at a particular time stamp. Moreover, we have also predicted the behavior of drainage H d / h g and retention H r / h g height along with corresponding times by considering important pertinent parameters. The drainage and retention height are noticed to be lower and higher, respectively, with the rise of crossflow strength for a constant bubble size. We have further attempted to predict a regime map to distinguish two important behaviors of bubble, namely, (i) gaseous mass sheared off (zone I) and (ii) no gaseous mass sheared off (zone II). Finally, velocity vectors are employed to characterize the flow pattern of bubble passage through the liquid–liquid interface with the supplementary effect of crossflow. [ABSTRACT FROM AUTHOR]

In this study, the effect of different arrangements of injectors on the injection of liquid water into the hot supersonic crossflow of cylindrical geometry on the performance and the rate of evaporation has been studied using a numerical method. The crossflow has a Mach of about 2 and a total temperature of 800 K. At first, the penetration height and droplets produced by atomization in the supersonic flow are validated using the Lagrangian technique, and the results have been compared with the experiments. The usage of heat transfer equations and the evaporation model for the spray evaporation of droplets in the hot flow is also performed in the validation process, and the results are compared with the experimental results. Then, the injection into the examined geometry with four, six and eight injectors in three different arrangements was evaluated. The results indicate that employing an arrangement of eight injectors leads to the most significant reduction in total temperature, with average total temperatures decreasing to below 550 K. The results demonstrate a 40% decrease in total pressure, with a decrease in Mach number to about 1 at the end of the cylinder. Additionally, the evaporation rate shows higher evaporation of water in the eight-injector arrangement compared to other arrangements. [ABSTRACT FROM AUTHOR]

This study examines a cross-flow turbomachine designed for power generation in areas with limited discharge and head availability, focusing on sustainability, affordability, and ease of operation. It investigates how varying the number of blades in the runner affects turbine performance while keeping other design factors constant. Testing runners with 8, 12, 16, 20, and 24 blades under identical conditions reveal consistent RPM variations across different blade numbers for various parameter combinations. The study identifies a 12-blade configuration as optimal for electrification projects at selected sites. Experimental validation using the Taguchi technique confirms the reliability of the findings. Additionally, the research explores the turbine's performance under different nozzle tip elevations (18 cm, 16 cm, and 14 cm). The highest observed runner speed is 345 RPM for the 12-blade runner at an 8° angle of attack, with similar speeds recorded for the 24-blade runner under similar conditions. [ABSTRACT FROM AUTHOR]

The article in the Journal of Fluid Mechanics delves into the impact of plasma-based base flow modification (BFM) on swept-wing boundary layers, specifically focusing on controlling cross-flow instabilities (CFIs) and laminar-turbulent transition. Through numerical simulations and experimental data, the study predicts a stabilizing effect on CFIs with plasma actuators, highlighting the potential for transition delay with specific flow parameters. The findings offer valuable insights into the use of plasma actuators for boundary layer control, emphasizing the intricate relationship between stationary and traveling CFIs in fluid dynamics research. [Extracted from the article]

The article "Turbulent flow around convex curved tandem cylinders" delves into the turbulent flow dynamics around curved tandem cylinders through direct numerical simulation. It uncovers various flow regimes in the gap between the cylinders, each linked to different Strouhal numbers and characterized by interactions between primary instability, shear layer instability, and flow mode alterations. The study emphasizes the intricate interplay of different flow modes and their impact on the overall flow behavior, shedding light on the complex vortex dynamics and shear layer instability in the wake of convex curved tandem cylinders at a Reynolds number of 3900. [Extracted from the article]

The document delves into hypersonic boundary layer theory in the symmetry plane, focusing on simplified laminar boundary layer equations for blunt bodies like flat plates, cones, and spheres. Special cases such as stagnation point flows are also addressed, with solutions provided for different geometries. The research articles included cover topics like heat flux estimation, pressure distributions, and boundary layer transition, contributing to the understanding of hypersonic flow dynamics and boundary layer behavior in aerospace engineering. [Extracted from the article]

The study examines the wake dynamics of a heated square cylinder in the presence of thermal buoyancy through numerical simulations. It reveals a transition from chaotic to periodic or quasiperiodic patterns as heating levels increase, with the onset of three-dimensionality triggered at a critical Reynolds number of 173. The research also delves into the influence of baroclinic vorticity production on wake dynamics and the variation of wake behavior with increasing heating levels. The document compiles research articles on fluid dynamics, heat transfer, and flow transitions related to square cylinders and other geometries, contributing to the understanding of complex fluid dynamics phenomena. [Extracted from the article]

Numerical simulations are carried out on the vortex-induced rotations of a freely rotatable rigid square cylinder in a two-dimensional uniform cross-flow. A range of Reynolds numbers between 40 and 150 and density ratios between 0.1 and 10 are considered. Results show eight different characteristic regimes, expanding the classification of Ryu & Iaccarino (J. Fluid Mech. , vol. 813, 2017, pp. 482–507). New regimes include the transition and wavy rotation regimes; in the ${\rm \pi}$ -limited oscillation regime we observe multipeak subregimes. Moment-generating mechanisms of these regimes and subregimes are further elucidated. A phenomenon related to the influence of density ratio is the tooth-like shape of the ${\rm \pi} /2$ -limit oscillation regime observed in the regime map, which is explained as a result of the imbalance relation between the main frequencies of rotation response and the vortex shedding frequency. In addition, existence of multiple regimes and multistable states are discussed, indicating multiple stable attractive structures in phase space. [ABSTRACT FROM AUTHOR]

Vortex-induced vibration (VIV) of a low mass ratio circular cylinder ( m * = 10), that is free to vibrate in crossflow and in-line directions, at supercritical Reynolds number (3 × 10 5 ) has been studied using large-eddy simulation for a range of reduced speed (2 ≤ U * ≤ 11). In the supercritical regime, the boundary layer transitions to a turbulent state via the formation of a laminar separation bubble (LSB). The regime is associated with weakened vortex shedding, resulting in subdued VIV response. Lock-in is observed for U * ≥ 3. The cylinder vibration frequency is identical in the crossflow and in-line directions, leading to an elliptical trajectory. The rms of the force coefficients is similar to that for a stationary cylinder in the desynchronization regime while it decreases with increase in U * during lock-in. The spatiotemporal dynamics of LSB is explored. The LSB is sedentary in the desynchronization regime, while it undergoes significant circumferential movement, in each cycle of cylinder oscillation, in the lock-in regime. The mode of vortex shedding, determined from the arrangement of vortices in the span-averaged instantaneous flow as well as the phase difference between the lift and cylinder response, is C(2S) in the desynchronization regime. It is 2 P 0 in the lock- in regime. [ABSTRACT FROM AUTHOR]

To investigate the characteristics of the bi-stable flow at subcritical Reynolds numbers, large eddy simulation is adopted to simulate the crossflow around two tandem circular cylinders at Re = 3900. The reattachment/co-shedding bi-stability is observed in the simulations with spacing ratios (L/D, L is the center-to-center cylinder spacing and D is the diameter) of 4.5 and 4.7. Statistical analyses are performed on the hydrodynamic coefficients, time-averaged flow fields, three-dimensional characteristics, wake pattern, and vortex shedding frequencies at different spacing ratio and time period. In addition, a detailed analysis and explanation were conducted on the secondary vortices identified in the reattachment flow regime, revealing that the secondary vortices, generated from the instability of the shear layer, significantly influence the variation in vortex shedding frequency over time. The reduced-order variational mode decomposition method is employed to decompose the flow field during the flow regime transitions, unveiling their spatial and temporal features. It is revealed that the shear layer instability and the low-frequency modulation behavior are the predominant factors triggering the bi-stable phenomenon at subcritical Reynolds numbers. This study aims to uncover triggering mechanisms underlying the bi-stable phenomenon in the flow around two tandem cylinders and provides valuable insight for relevant engineering applications. [ABSTRACT FROM AUTHOR]

The effect of the mutative side ratio (D/B) on the vortex-induced vibration (VIV) characteristic, aerodynamic characteristics, and the surrounding time-averaged and transient flow field of a rectangular cross section model were simulated numerically. Based on Fluent 19.0 platform, overset grid technology and the fourth-order Runge–Kutta method were used at Re 22 000. First, a rectangular cross section model with D/B = 0.25 was selected, and the simulation method and parameter settings were validated against previous literatures. The subsequent analysis compared and evaluated the effect of side ratio on the VIV response by focusing on statistical values of aerodynamic force coefficients, self-spectra, amplitude ratio, motion trajectory, and phase transition changes for stream-wise and cross-flow directions. Moreover, the study examined the influence of different models at different reduced velocities (Ur) on wake vortex-shedding. The findings suggest that, within a fixed cross-sectional area, a smaller side ratio leads to a weaker VIV characteristic and notably lower aerodynamic performance compared to a larger side ratio. The vortex-shedding mode of the rectangular cross section, particularly with a large side ratio, is less sensitive to changes in Ur compared to the standard square cylinder. An examination of the Reynolds number (Re) effect on the minimum and maximum side ratio models reveals that it has a more pronounced impact on the aerodynamic performance and VIV of the cross-flow when compared to in-line flow. In general, it is noted that larger side ratio model exhibits a stronger sensitivity to the variation of Re. [ABSTRACT FROM AUTHOR]

This study combines the experimental and numerical simulation methods to deeply analyze the impact of liquid crossflow on the discharge coefficient of a gas jet hole on a flat plate. Experiments were conducted to examine the influence of momentum flux ratio and theoretical momentum flux ratio on the discharge coefficient under various crossflow Reynolds numbers. It was found that the variation of the discharge coefficient with the theoretical momentum flux ratio clearly reflects the impact of the crossflow boundary layer velocity profile on the discharge coefficient. The rapid growth of velocity in the boundary layer near the wall in the direction normal to the wall surface, or the decrease in the thickness of the boundary layer, both enhance the shearing effect of the crossflow, leading to a decrease in the discharge coefficient. Analysis of the cavity morphology at the hole exit captured by high-speed camera revealed that the averaged profile of the gas–liquid boundary on the symmetrical plane of the jet below the hole can be approximated as a straight line within the scale of the hole diameter, and the sine of the angle between this line and the upper wall surface is roughly equivalent to the normalized discharge coefficient. This relationship was physically interpreted through the analysis of effective and equivalent flow cross-sectional shapes derived from numerical simulation at different crossflow Reynolds numbers and theoretical momentum flux ratios. Additionally, this paper introduces an innovative method for predicting jet flow rate based on image processing technology. A notable feature of this method is that it does not require the measurement of the pressure inside the gas chamber. [ABSTRACT FROM AUTHOR]

This study presents the breakup mechanisms and droplet features of a liquid jet introduced into a low-speed cross air flow. The main aim of this study is to investigate the spray behavior of water when exposed to a uniform crossflow of air at very low velocities. A shadow sizing system is employed to collect comprehensive data for analyzing the interactions between liquid jets and crossflowing air. Three different nozzles were used to examine the distribution, penetration, and breakup characteristics of water jets in an air crossflow. It is worth highlighting that the Weber number in this experiment was maintained at a very low level. Both the jet Weber number (1.3 < Wej < 119) and the gas Weber number (0 < Weg < 1), along with the momentum flux ratio (2 < q < 14400), are crucial dimensionless parameters significantly affecting various droplet properties such as size, velocity, shape, and breakup behavior. This study investigates the structural features, trajectory of the jet, and duration of breakup near the nozzle. Subsequently, the experimental results are tabulated for future numerical and analytical studies. As the air crossflow velocity increases, the liquid jet bends in the direction of the airflow. The breakup length decreases with increasing air velocity. The nozzle with medium diameter shows the maximum dimensionless breakup length. At a constant air velocity, the breakup length initially increases and then decreases with an increasing momentum flux ratio. Higher liquid flow rates result in a higher density of smaller droplets. The liquid jets shift upstream with increasing q values; however, due to the wide range of q values, existing empirical relations in the literature fail to accurately predict this behavior. [ABSTRACT FROM AUTHOR]

This paper is motivated by an interest in understanding the characteristics of buoyant fluids discharged from the bottom wall of channels, such as encountered during tunnel fires or in river effluent discharge. Direct numerical simulation is used to model the upward release of a planar buoyant jet or plume from the bottom wall of a channel into an incoming turbulent crossflow. The well-studied jet-in-crossflow with only a momentum source is simulated first, and subsequently, fixing the incoming Reynolds number, buoyancy source as heat flux is added alongside varying momentum source, with two cases where only a buoyancy source is present. Appropriate five non-dimensional parameters relevant for this flow are defined, of which three are fixed and two—source to channel momentum ratio and Richardson number—are varied. The changes in turbulence characteristics as the buoyant jet or plume evolves downstream are presented. In all cases with buoyancy, except for the pure jet case, the plume is initially confined to the lower half of the channel before it suddenly lifts to the top half, an effect that occurs at an increasingly smaller downstream distance with increasing buoyancy, and dividing the flow into a near and far field. The distributions of mean and Reynolds stresses in the near and far field of the source are reported, and it is found that the channel flow becomes more turbulent downstream of the source, and further, the turbulent vertical temperature flux switches sign from near to far field owing the a change in the mean temperature gradient sign. From the input parameters and using the integrated temperature equation a reasonable estimate of the far field mean channel temperature can be obtained by a reference temperature based on the heat conservation that includes the convective and diffusive source heat flux. A monotonic behaviour of the back-layering distance is also observed a function of this reference temperature, which was difficult to obtain with the two specified non-dimensional parameters. [ABSTRACT FROM AUTHOR]

Direct numerical simulation of a turbulent forced buoyant plume in a crossflow is performed at a source Reynolds number Re 0 = 1000 , Richardson number Ri 0 = 1 , Prandtl number Pr = 1 and source-to-crossflow velocity ratio R 0 = 1 . The instantaneous and temporally averaged flow fields are assessed in detail, providing an overview of the flow dynamics. The velocity, temperature and pressure fields are used together with enstrophy fields to describe qualitatively the evolution of the plume as it is swept downstream by the crossflow, and the mechanisms involved in its evolution are outlined. The plume trajectory is determined quantitatively in a number of ways, and it is shown that the central streamline and the centre of buoyancy of the plume differ significantly—as with jets in crossflow, the central streamline is seen to follow the top of the plume, whereas the centre of buoyancy, by definition, describes the plume as a whole. We then investigate the turbulence properties inside the plume; in particular the eddy viscosity and diffusivity are presented, which are significant parameters in turbulence modelling. Assessment of turbulence production demonstrates the presence of regions where turbulence kinetic energy is redistributed to the kinetic energy of the mean flow, implying a negative eddy viscosity within certain regions of the domain. Similarly, the observation that the buoyancy flux and buoyancy gradient are anti-parallel in specific regions of the flow implies a negative eddy diffusivity in said regions, which must be realised in models of such flows in order to capture the countergradient transport of thermal properties. A characteristic eddy viscosity and diffusivity are presented, and shown to be approximately constant in the fully developed regime, resulting in a constant characteristic turbulent Prandtl number, in turn signifying self-similarity. [ABSTRACT FROM AUTHOR]

We investigated plume dispersion for neutrally-buoyant and dense scalars diffusing from the free end of a low-aspect ratio, bed-mounted cylinder in laminar crossflow. We were motivated by the need to understand dispersal patterns in controlled flow environments for odors emanating from the Training Aid Delivery Device (TADD), a commonly used device in canine scent-detection training. We evaluated the effects of crossflow velocity (Reynolds numbers, Re from 0 to 255) and scalar density (specific gravities, SG from 1 to 1.29) using complimentary numerical and experimental approaches and found a persistent bimodal plume structure in the far-field with symmetrical off-centerline concentration peaks. The bimodality is driven by near-field scalar entrainment in the downwash over the free end of the cylinder and its subsequent far-field evolution in near-bed horseshoe vortices. In dense plumes, local body forces alter dispersion characteristics further by directly modifying the global wake structure. Lateral dispersion is significantly enhanced across all Re and SG relative to pure diffusion; density effects, however, produce opposing trends in the effective lateral diffusivity with increasing Re. The lateral spread of neutrally-buoyant scalars is enhanced with increasing Re while it diminishes for dense scalars, highlighting the nuanced connection between Re, scalar density, and lateral plume dispersion. Given the centrality of the horseshoe vortex in far-field dispersion characteristics seen here, and its ubiquity in environmental flows around bed-mounted obstacles, the present investigations provide a valuable contribution in a relatively understudied regime with a diffusive end source on a low aspect-ratio cylinder in crossflow. Plain Language Summary: Numerical and experimental study of passive and dense plume dispersion around low-aspect ratio, bed-mounted cylinders in laminar crossflow. Persistent bimodal plume structures are driven by near-field entrainment in cylinder downwash and far-field evolution in nearbed horseshoe vortices. At fixed Reynolds number, local body forces in dense plumes enhance lateral dispersion by modifying the strength and structure of the downwash and horeshoe vortex. Lateral disperion is enhanced with increasing Reynolds numbers for neutrally-buoyant scalars while it is diminished for dense scalars. [ABSTRACT FROM AUTHOR]

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Crossflow filtration is a separation technique where fluid flows tangentially across a membrane or porous media, reducing clogging by sweeping away retained particles and allowing continuous filtration. Dispersion of solute matter in crossflow filtration plays an essential role in the separation performance of many industrial processes. The current work aims to generalize the Taylor dispersion theory and study the solute transport in a slit–porous medium system with a crossflow. The solute is depleted by the porous medium at the slit top porous wall or the interface between the slit and the porous medium, where the continuity of the solute concentration and mass flux is applied. The solute is simultaneously transported axially by the main flow along the slit and vertically by the crossflow perpendicular to the slit. Using the Reynolds decomposition and cross-sectional averaging techniques, the generalized reduced-order model for the advection-dispersion solute transport in the slit–porous medium system with the presence of a crossflow is established, where the effective velocity of the main flow and the effective dispersion coefficient are obtained. The analysis of the results reveals that the nondimensional Taylor dispersion coefficient scales with the Peclet numbers for the crossflow and the main flow, respectively, as D T ∼ Pe v − 5 / 3 (when Pe v ≥ 20) and D T ∼ Pe u 2 . The proposed theoretical model, along with the findings of this study, paves the way for the fundamental study of dispersion in more complex systems. [ABSTRACT FROM AUTHOR]

The atomization characteristics of liquid jets injected transversely into a supersonic crossflow significantly affect the performance of scramjet engines. Existing research on this topic has mainly focused on circular nozzles, while the influence of nozzle geometry, particularly elliptical nozzles, has received relatively limited attention. Therefore, this study employs a numerical simulation method coupling the volume of fluid and discrete particle model to investigate the breakup and atomization characteristics of transverse liquid jets from elliptical nozzles with different aspect ratios under supersonic crossflow conditions, as well as the total pressure loss. The simulation model is validated against experimental data obtained from a pulse wind tunnel, including measurements of the liquid jet penetration depth and the Sauter mean diameter (SMD). The results indicate that for elliptical nozzles with an aspect ratio (AR) greater than 1, columnar breakup occurs earlier, and the columnar breakup length is shorter compared to circular nozzles. As the AR increases, the jet penetration depth decreases, while the spray expansion angle increases. Furthermore, the SMD of the atomized spray field from the circular nozzle is larger than that from the elliptical nozzles, and the SMD of the spray field is smallest for an elliptical nozzle with AR of 4. Finally, the elliptical nozzles exhibit a higher total pressure recovery coefficient, indicating reduced total pressure loss in the combustion chamber. This reduction in pressure loss is expected to improve the thrust performance of the scramjet engine. [ABSTRACT FROM AUTHOR]

The canonical scenario of cross-flow vortex-induced vibration (VIV) of a circular cylinder in the turbulent regime, which has been studied by several physical experiments in the literature, is reexamined in this study through high-fidelity large-eddy simulations (LES) at a Reynolds number 104. The VIV response (including vibration amplitude and frequency) and hydrodynamic coefficients predicted by the present LES agree with the experimental results better than previous numerical attempts. In addition, several phenomena reported by previous experimental studies are confirmed numerically for the first time. After validating against the experiments, new VIV characteristics and physical mechanisms are explored with confidence. First, a collective analysis on the frequency spectra of the displacement, lift, and velocity signals provides a complete picture of the frequency response of the system. In contrast, the use of a single signal may miss certain aspects of the frequency response, so that caution should be exercised. Second, spanwise correlation of primary vortex shedding is examined, where relatively low correlations in the upper and lower branches are likely because the vortex shedding patterns involve complex vortex generation and interaction. Third, the effect of mass ratio (m*) of the cylinder on the VIV response is analyzed with a range of m* (=1.4–3.4) relevant to cylindrical structures used in offshore engineering (such as subsea pipelines). The variations in the amplitude response, frequency response, and hydrodynamic coefficients with m* and reduced velocity are examined in detail. The present results suggest that a lighter pipeline is more susceptible to the onset of VIV. [ABSTRACT FROM AUTHOR]

Nonmodal linear stability analysis results are presented for hypersonic flow over a cone at 6° angle of attack complementing earlier modal stability analysis. Based on the parallel flow assumption, singular value decomposition is applied to obtain the optimal linear combination of global crossflow modes. The optimal disturbance exhibits significant transient growth in the initial short distance and progressively follows the path of the most unstable mode downstream. The largest transient energy gain is observed for disturbances at around 40 kHz close to the most amplified modal frequency and tends to increase with the Reynolds number. The optimal disturbance initially exhibits two amplitude peaks in the azimuthal direction, one lying in the leeward region where the unstable crossflow modes reside and the other in the windward region where the adjoint modes exist. As the optimal disturbance travels downstream, the second amplitude peak rapidly shifts toward the leeward side and reaches the optimal energy gain when it eventually merges with the first amplitude peak. The evolution process of the optimal disturbance indicates that the optimal disturbance might have exploited the locally crossflow instability through traveling from the windward side to the leeward side. [ABSTRACT FROM AUTHOR]

An oscillating flow past a structure represents a complex, high-dimensional, and nonlinear flow phenomenon, which can lead to the failure of structures due to material fatigue or constraint relaxation. In order to better understand flow-induced vibration (FIV) and coupled flow fields, a numerical simulation of a two-degrees-of-freedom FIV in a cylinder was conducted. Based on the Lagrangian-based dynamic mode decomposition (L-DMD) method, the vorticity field and motion characteristics of a cylinder were decomposed, reconstructed, and predicted. A comparison was made to the traditional Eulerian-based dynamic mode decomposition (E-DMD) method. The research results show that the first-order mode in the stable phase represents the mean flow field, showcasing the slander tail vortex structure during the vortex-shedding period and the average displacement in the in-line direction. The second mode predominantly captures the crossflow displacement, with a frequency of approximately 0.43 Hz, closely matching the corresponding frequency observed in the CFD results. The higher dominant modes mainly capture outward-spreading, smaller-scale vortex structures with detail displacement characteristics. The motion of the cylinder in the in-line direction was accompanied by symmetric vortex structures, while the motion of the cylinder in the crossflow direction was associated with anti-symmetric vortex structures. Additionally, crossflow displacement will cause a symmetrical vortex structure that spreads laterally along the axis behind the cylinder. Finally, when compared with E-DMD, the L-DMD method demonstrates a notable advantage in analyzing the nonlinear characteristics of FIV. [ABSTRACT FROM AUTHOR]

In this study, heat transfer behavior in a channel adapted with a set of equilateral triangular prisms was investigated experimentally in a turbulent flow regime, with a range of Reynolds numbers corresponding to 1x104

Vibration and rotation represent two common fluid–structure-interaction phenomena, which can occur independently or concurrently. While extensive research has been conducted on individual vibration/rotation cases, there is relatively limited literature on coupled cases. However, it is crucial to recognize that coupled responses, such as those observed in falling leaves, are more prevalent in both natural occurrences and engineering scenarios. Hence, this study aims to investigate the influence of cross-flow vibrations on the flow-induced rotations of an elastically mounted cylinder-plate system. A broad range of rotational reduced velocities, spanning Uθ = 2–18, is examined across four distinct vibrational reduced velocities, namely Uy = 5, 8, 12, and 18. Numerical results indicated that a bifurcation phenomenon, wherein the cylinder-plate deflects to a non-zero equilibrium position, occurs at relatively high values of Uθ and Uy. Four distinct response modes have been identified: vibration-dominated, rotation-dominated, augmentation (VIV-like), and augmentation (galloping-like) mode. These response modes exert significant influence on phase angles between rotary angle and displacement as well as vortex shedding modes. In the rotation-dominated region, VIV-like region, and galloping-like region, phase angles exhibit a continuous decreasing trend, a consistent level of 180° and 90°, respectively. Transitions between vibration and rotation responses result in sharp increases in phase angles. The wake flow in the rotation-dominated mode and VIV-like mode demonstrates a 2S mode (two single vortices), while the vibration-dominated mode is characterized by a predominant 2T mode (two triplets of vortices). In the galloping-like region, large amplitudes lead to the increase in numbers of vortices, presenting 2S, 2S*, and 2P (two pairs of vortices) mode at Uy = 8, and 2P, P + S (one pair and one single vortices) and 2P+S (two pairs and one single vortices) mode at Uy = 12, where the 2S* mode consists of two single vortices, each exhibiting a tendency to split into two smaller vortices as they migrate downward. The mechanism behind the notable amplification of rotation/vibration responses is elucidated. Apart from the pressure difference induced by vortex shedding, the additional driving force resulting from relative motion in the transverse direction contributes to the total torsional force, thereby leading to significant rotary responses. Furthermore, the streamlined profile accounts for the escalation in vibration amplitudes. [ABSTRACT FROM AUTHOR]

The vortex-induced vibrations of two side-by-side flexible cylinders in a uniform flow were studied using a three-dimensional direct numerical simulation at Reynolds number Re = 350 with an aspect ratio of 100, and a center-to-center spacing ratio of 2.5. A mixture of standing-traveling wave pattern was induced in the in-line (IL) vibration, while the cross-flow (CF) vibration displayed a standing-wave characteristic. The ninth vibration mode prominently occurred in both IL and CF directions, along with competition between multiple modes. Proximity effects from the neighboring cylinder caused the primary frequency to be consistent between IL and CF vibrations for each cylinder, deviating from the IL to CF ratio of 2:1 in isolated cylinder conditions. Repulsive mean lift coefficients were observed in both stationary and vibrating conditions for the two cylinders due to asymmetrical vortex shedding in this small gap. Comparatively, lift and drag coefficients were notably increased in the vibrating condition, albeit with a lower vortex shedding frequency. Positive energy transfer was predominantly excited along the span via vortex shedding from the cylinder itself and the neighboring one, leading to increasing lower-mode vibration amplitudes. The flip-flopping (FF) wake pattern was excited in the stationary and vibrating cylinders, causing spanwise vortex dislocations and wake transition over time, with the FF pattern being more regular in the stationary cylinder case. [ABSTRACT FROM AUTHOR]

The sport of half-pipe skiing, characterized by its dynamic maneuvers and highspeed descents, often faces challenges posed by unpredictable wind conditions. To address this, an advanced wind-blocking system incorporating an air curtain capable of generating a jet flow is proposed. This pioneering design offers a dual advantage: the system can significantly reduce the windbreak size in the vertical dimension while maintaining a satisfactory wind-blocking effect. A comprehensive study is conducted to analyze the effects of the height of the windbreak and the jet emission angle from the air curtain. When the jet speed is 40 m/s, a 50° emission angle and a 2 m height of the windbreak result in an optimal wind-blocking effect. Furthermore, delving deeper to understand the underpinnings of this phenomenon, we discovered that a counterrotating vortex pair, which forms in the presence of this jet under crossflow conditions, plays a pivotal role in augmenting the wind-blocking capabilities of the system. [ABSTRACT FROM AUTHOR]

X‐band marine radar observations and a hindcast simulation from a 3D hydrostatic model are used to provide an overview of Connecticut River (USA) ebb plume front expansion into the strong tidal crossflow of eastern Long Island Sound. The model performance is evaluated against in situ and remote sensing observations and demonstrates dominant control of the front by semidiurnal tides. The recurring frontal evolution is classified into three dynamical stages of arrest, propagation, and advection. A conceptual model that follows this progressing balance between outflow buoyancy and crossflow momentum qualitatively reproduces frontal evolution in both the radar observations and the hindcast. The majority of the residual, intertidal variability of front timing and geometry is explained by co‐varying tidal amplitude, freshwater discharge, and wind stress using a multi‐linear regression analysis of the radar observation record. Intrinsic front speeds in the modeled frontal propagation are compared with the analytical model of Benjamin (1968, https://doi.org/10.1017/s0022112068000133), with better agreement achieved after accounting for ambient near‐surface shear associated with wind forcing. Plain Language Summary: The fresh buoyant water that exits the Connecticut River mouth (USA) during each ebb tide expands as a plume, and floats above the denser waters of Long Island Sound. Currents in the Sound flow back and forth along the coast each tide, pushing the plume along the shore first to the east and then to the west. The location of the plume boundary (front) goes through a similar cycle almost every tide, initially being held stationary by eastward tidal currents, then expanding freely around slack tide, and subsequently being aided as it moves to the west by the ambient flow. Small changes to the arrival time and shape of the front are linked to changes in river discharge, tidal strength, and winds. Realistic simulations using a type of numerical model that aids coastal decision making are able to reproduce the tidal progression of front movement that was observed in 6 weeks of marine radar images of the water surface. Front movement in the numerical model also fits a simple analytical theory to a degree not previously seen on such a large scale, despite the complicating effects of wind. Key Points: Buoyant ebb plume front kinematics in a tidal cross‐flow are characterized by stages of arrest, propagation, and advectionWind, tide, and discharge variations explain modifications to the dominant semidiurnal control of the Connecticut River plume frontFront propagation in a hydrostatic numerical model reproduces both radar remote sensing observations and gravity current theory [ABSTRACT FROM AUTHOR]