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Wingtip-flow effects on the aerodynamic forces and moments of a wing become increasingly significant as the aspect ratio decreases. These effects are dominated by the tip vortex and an associated s...

In a fuel-efficient extended formation flight of commercial airplanes, the aerodynamic benefits depend on one’s ability to surf wake vortices. This paper presents a wake vortex detection scheme bas...

Experimental investigations are presented on the characterization of flow turbulence and velocity fields around circular piers placed in isolated, tandem, and staggered arrangements in a rigid bed channel with identical flow conditions. Instantaneous velocity measurements are undertaken using a 16 MHz micro down-looking Acoustic Doppler Velocimeter (ADV) at different grid points along the flow depth. The streamline pattern obtained from the velocity fields is presented on vertical planes around the piers. Further, the resultant contours of vortices are plotted for all three types of arrangements, i.e., isolated, tandem, and staggered arrangements, to understand the strength of the vortices around the piers. Apart from the above investigations, the turbulence characteristics such as turbulence intensities, turbulent kinetic energy, velocity power spectra and Reynolds shear stresses at different planes are also presented for all three configurations of piers. The turbulence characteristics are used to identify the influence of one pier over others in the tandem and staggered arrangements compared to that of the isolated piers. The horseshoe vortex system, quantified by its vorticity and strength, is found to be predominant in the staggered configuration. A horseshoe vortex is formed at 0.36d, 0.9d and 0.35d (d is the diameter of the pier) upstream of the isolated pier, front piers of the tandem and front piers of the staggered case, respectively. A zone of recirculation is formed just upstream of the rear pier in the tandem case. The Reynolds shear stresses near the bed, turbulent kinetic energy and turbulence intensities are also found to be quite significant downstream of the front pier in the staggered arrangement compared to those in the isolated and tandem arrangements. The turbulent kinetic energy at the mid-flow depth is found to be 2.5 times higher than that near the bed. The velocity power spectra reveals that the strength of wake vortices is 2.5 times greater for the front piers of the staggered case than that of the tandem front piers with Strouhal numbers, $${S}_{t}$$ = 0.26 and 0.112 for the staggered and tandem cases, respectively, near the bed. The present study enhances the understanding of the flow structure around isolated, tandem and staggered bridge piers.

A wind tunnel experiment was carried out to characterize the flow surrounding rectangular prisms of varying permeability, each set mounted on a stationary plane-bed surface and subsequently on an erodible bed. Laser-Doppler anemometer measurements of the horizontal and vertical velocity components were obtained in a grid that included an area adjacent to the windward face, enveloped the free end of the form, and extended ≈6.5 element heights downwind of the rear wall. From these component measurements, the total velocity (Tuw), turbulence intensity (TI), Reynold Stress (RS) and the turbulence kinetic energy (TKE) were calculated throughout the sampling array. As compared to an impermeable same-sized cube, the near-surface TKE and RS were substantially reduced within the wake flow behind the permeable elements. In the plane-bed experiments, TI generally increased downwind of the permeable cubes, opposite to the trend for the impermeable form. The distinction in TI was less pronounced, however, when the bed morphology developed scour marks. The impermeable cube had the largest amount of erosion relative to its volume, in response to strong downwash along its windward face and the development of an energetic horseshoe vortex. This coherent flow structure was not detected for all permeable forms and the amount of scour was orders of magnitude less. This study would suggest that for restricting erosion, the efficiency of a surface-mounted element can be improved by making the walls of the form permeable rather than solid, thereby increasing energy dissipation in the wake flow while reducing vortex impingement and bed shear stress.

Implementations of lifting-line theory predict the lift of a finite wing using a sheet of semi-infinite vortices extending from a vortex filament placed along the locus of aerodynamic centers of th...

Merging of corotating vortices is of primary interest in the field of supersonic mixing due to the ability of two or more structures to coalesce and form a larger one which enhances the stirring mo...

In order to apply the air fin successfully and ensure the maneuverability of hypersonic vehicle, a key problem to be studied urgently is the heat flux brought by the fin mounting gap. The appearance of mounting gap and fin shaft can induce many complex flow structures which need more attentions to be investigated. Under Ma 6, Nano-tracer-based Planar Laser Scattering (NPLS) and Temperature Sensitive Paints (TSP) were applied to visualize and measure transient flow structures and heat flux distribution of a swept fin-induced flow field with different height mounting gaps. Complementarily, Reynolds-averaged N-S equations were solved with k-ω SST turbulent model. The heat flux distribution results of numerical simulation and TSP observed the change of high heat flux region with different mounting gap, both in position and magnitude. The streamlines based on Computational Fluid Dynamics (CFD) and flow visualization results obtained by NPLS revealed the cause of high heat flux region. The high heat flux region in this flow field is mainly related to the reattachment of vortex and flow stagnation. The increase of gap height can lead to stronger gap overflow and shaft-induced horseshoe vortex, which are source of the high heat flux around the fin. The case with the highest mounting gap (4 mm) en-counters the most severe aerodynamic heating, both on the surface of fin and plate. Thus, under the premise of ensuring the flexibility of the fin, the gap should be set as small as possible.

The submerged inlet is an attractive configuration for advanced helicopters due to its high stealth performance and low external drag. In this paper, a submerged inlet, integrated with a ROBIN helicopter fuselage and a simplified power output shaft, is experimentally and numerically investigated to obtain the basic flow characteristics under a freestream velocity of 23.6 m/s. The results indicate that the pylon ahead of the inlet induces a horseshoe vortex. Though the vortex is ingested into the inlet, it has little effect on the internal flows and can be neglected. When the airflow enters into the inlet, it interacts with the shaft with a large incidence angle, yielding a vortex pair. At the leeside of the shaft, the two side flows of the shaft impinge at the center plane, generating a local high-pressure region at the azimuthal angle of 180°, which forces the boundary layer to roll up a counter-rotating vortex pair. In addition, the airflow adjacent to the cowl lip accelerates rapidly, resulting in a local low-pressure region at the azimuthal angle of 0°. Therefore, the inlet duct has a strong circumferential pressure gradient, which originates from an azimuthal angle of 180° to 0° and induces a vortex pair at the azimuthal angle of 0°. The three vortex pairs are the main origins of the distortion at the duct exit plane, among which the one near the cowl lip with the azimuthal angle of 0° plays the dominant role. Additionally, as the velocity ratio increases from 3.9 to 5.5, the circumferential pressure gradient and the cowl lip vortex get intensified, which causes that the total-pressure recovery coefficient drops by 0.5% and the distortion index increases by 28%. A submerged inlet, integrated with a ROBIN helicopter fuselage and a simplified power output shaft, is experimentally and numerically investigated. Three vortex pairs, which locate at the azimuthal angle of 0°, the leeside of the shaft, and 180° of the inlet surface, are the main origins of the distortion of the inlet, among which the one near the cowl lip with the azimuthal angle of 0° plays the dominant role. As the velocity ratio increases, the circumferential pressure gradient gets intensified, leading to stronger vortex pairs.

A comprehensive review of the local scour due to vortical flow around a cylindrical bridge pier under steady current is presented in this paper. The mechanism of the formation of vortices, the size, velocity and strength of horseshoe vortex (HSV), formation of the HSV by the separation of laminar and turbulent boundary layer and the scour around a cylindrical pier due to vortices have been presented. The complexity involved in the scour-related calculations, and the scope for future research are discussed in the last section.

The flow physics aspects of parallel sonic transverse gaseous injections in a Ma = 2.95 supersonic crossflow are experimentally investigated in this study. NPLS (Nanoparticle-based Planar Laser Scattering) and oil flow techniques are employed for qualitative comparison. Under the supersonic crossflow with jet-to-crossflow momentum flux ratio (J) of 7.7, the NPLS images reveal the shock structures, K–H vortex and slip lines on different spanwise planes of each of the experimental conditions, and the oil flow experiments illustrate the bow shocks, separation zones and other interactions in the near-wall region. Furthermore, the fractal dimensions of the jets mainstream region are given to analyze the turbulent intensity. The interaction mechanism of the flow field is completely different with the distances of the orifices growing. As the orifices are close together, the flow structures of three orifices, including bow shocks, separation zone, horseshoe vortex and jet mainstreams, almost merge into one. With the distances between jets growth, the bow shocks would merge into a normal shock and the separation zones interact with each other. When the distances between jets are large enough, the jet mainstreams are independent, while the bow shocks interact with each other forming a complex shock system. The interactions between jets promote the development of turbulence in general, while the interactions between too close jets would restrict the development of turbulence. In addition, the horseshoe vortex and the shedding vortex are analyzed.

The three-dimensional flow separation over the Rood wing-body junction is an exemplar application of separation affecting many important flows in turbomachinery and aerodynamics. Conventional Reynolds Averaged Navier Stokes (RANS) methods struggle to reproduce the complexity of this flow. In this paper, an unconventional use is made of a hybrid Reynolds Averaged Navier Stokes (RANS) model to tackle this challenge. The hybridization technique combines the Menter k − ω − S S T model with the one equation sub-grid-scale (SGS) model by Yoshizawa through a blending function, based on the wall-normal distance. The hybrid RANS turbulence closure captured most of the flow features reported in past experiments with reasonable accuracy. The model captured also small secondary vortices at the corner ahead of the wing nose and at the wing trailing edge. This feature is scarcely documented in the literature. The study highlights the importance of the spatial resolution near the wing leading edge, where this localized secondary recirculation was observed by the hybrid RANS model. It also provides evidence on the applicability of the hybrid Menter and Yoshizawa turbulence closure to the wing-body junction flows in aircraft and turbomachines, where these flows are characterized by a substantially time-invariant three-dimensional separation.

Previous studies show that the tip clearance loss limits the improvement of pumpjet propulsor (PJP) performance, and the tip clearance flow field is the most complicated part of PJP flow. In this work, the noncavitation and cavitation hydrodynamic performances of PJP with a tip clearance size of 1mm are obtained by using the detached-eddy simulation (DES). At constant oncoming velocity, cavitation first occurs on the duct and then disappears with the decrease of the advance ratio. The rotor blade cavitation occurs at the low advance ratio and comprises tip clearance cavitation, tip leakage cavitation, and blade sheet cavitation. In the rotor region, the typical vortices include tip separation vortex, tip leakage vortex, trailing edge shedding vortex, and blade root horseshoe vortex. Combined with the pressure distribution, both the Q and λ2 criteria give reliable results of vortex identification. The cavitation causes an expansion of tip leakage vortex in the circumferential direction and decreases the intensities of tip separation vortex in the whole tip clearance area and tip leakage vortex in the cavitation area, and enhances the strength of tip leakage vortex in the downstream non-cavitation area. Key words: pumpjet propulsor (PJP), hydrodynamics, cavitation, vortex, tip clearance vortex

The interaction between self-sustaining dual jets and supersonic laminar boundary layer is experimentally studied using the nanoparticle-based planar laser scattering in a Ma 2.95 supersonic low-turbulence wind tunnel for the first time. The typical fine flow structures, such as separation shock, “W” bow shock, barrel shock, horseshoe vortex, large-scale vortex structures and counter-rotating vortex pairs, are clearly identified by streamwise and spanwise flowfield images. The curves of jet penetration depth are fitted at the momentum ratio of 0.55 between self-sustaining dual jets and supersonic crossflow. The results play a significant role in further and comprehensive exploration of the active flow control for a supersonic flow.

The hydrodynamics in a straight open channel with a multiple-embayment groyne field was investigated using the detached-eddy simulation (DES). A series of short groynes were included on a 1:3 side slope of the channel. This work focuses on the turbulent coherent structures around groynes on an uneven bottom. Flows around groyne fields are characterized by massive separation and highly unsteady vortices. DES can capture a wide spectrum of eddies at a lower computational cost than the large eddy simulation (LES) or direct numerical simulation (DNS). In the present work, a zonal DES model (ZDES) was used to simulate the flow around groynes. The ZDES model is a modified version of the DES designed to overcome the model-stress depletion (MSD) of the RANS/LES hybrid model. The vortex system consists of the horseshoe vortex (HV) formed at the base of the obstructions, the necklace vortex (NV) that wrapped the groyne tips near the free surface, and the shedding vortex (SV) underneath the free surface. The effects of the incident flow and local topography on the vortex evolution were investigated by analyzing the mean flow structures and the instantaneous turbulent flow fields. Some important vortices cannot be captured because of the averaging process, while some flow structures cannot be observed in the instantaneous flow. The mean flow is only a reflection of the averaging process when complex vortices are present.

This paper is concerned with the flow characteristics and noise generation at the finite wing–wall junction. To characterize junction flow noise, acoustic measurements were taken in the aco...

In the current study, a three-dimensional CFD model is utilized to investigate the variation of the flow structure and bed shear stress at a single cylindrical pier during scour development. The scour development is presented by seven solidified geometries of the scour hole, collected during previous experimental work at different scour stages. Different turbulence models are evaluated and the (k-ω) model is chosen due to its relative accuracy in capturing the flow oscillation and vortex shedding at the pier downstream side with personal computer computational and storage resources. The numerical results are verified against dimensionless parameters from different previous experimental works. This research describes in detail the flow structure and bed shear stress variations through seven stages of the scour hole development. The dimensionless area-averaged circulation coefficient (Ψi) is developed to evaluate the changes in the vortex strength through the scouring process by eliminating the calculation area effect. It was concluded that the circulation in the (Y) direction is the main driving factor in the development of the scour hole more than the circulation in the (X) direction. The ratio between the horseshoe vortex (HV) mean size and the scouring depth (DV/dS) in addition to the location of the maximum bed shear stress are investigated during different stages of the scour development.

The mean flow and turbulence statistics of the flow through a simplified urban environment, which is an active research area in order to improve the knowledge of turbulent flow in cities, is investigated. This is useful for civil engineering, pedestrian comfort and for health concerns caused by pollutant spreading. In this work, we provide analysis of the turbulence statistics obtained from well-resolved large-eddy simulations (LES). A detailed analysis of this database reveals the impact of the geometry of the urban array on the flow characteristics and provides for a good description of the turbulent features of the flow within a simplified urban environment. The most prominent features of this complex flow include coherent vortical structures such as the so-called arch vortex, the horseshoe vortex and the roof vortex. These structures of the flow have been identified by an analysis of the turbulence statistics. The influence of the geometry of the urban environment (and particularly the street width and the building height) on the overall flow behavior have also been studied. Finally, the well-resolved LES results were compared with the experimental database from Monnier et al. to discuss differences and similarities between the respective urban configurations.

The origin and evolution of the three-dimensional flow structures around a pair of roughness cubes embedded in the inner part of a turbulent channel flow ( mm, corresponds to 91 wall units or 3.9 % of the half-channel height. They are aligned in the spanwise direction and separated by a, 1.5a and 2.5a. This paper focuses on the mean flow structure, and the data resolution allows detailed characterization of the open separated regions upstream, along the sides, on top of and behind the cubes, as well as measurements of wall shear stresses from velocity gradients. The flow features a horseshoe vortex, a vortical canopy engulfing each cube, a near wake arch-like vortex and multiple interacting streamwise vortices. Most of the boundary layer vorticity is entrained into the horseshoe vortex. The canopy, consisting of wall-normal vorticity to the sides, and spanwise vorticity on top of the cube, originates from the front surface. The streamwise vortices originate from realignment of the other components along the corners of the front surface. Merging of streamwise structures around and behind each cube causes formation of a large streamwise vortex rotating in the same direction as the inner horseshoe leg, with remnants of the outer leg under it. This merging occurs earlier and the entire flow structure becomes more asymmetric with decreasing spacing. Peaks and minima in the distributions of the wall shear stress are associated with the formation of and interactions among the near-wall vortices.

To design and optimize arrays of vertical-axis wind turbines (VAWTs) for maximal power density and minimal wake losses, a careful consideration of the inherently three-dimensional structure of the wakes of these turbines in real operating conditions is needed. Accordingly, a new volumetric particle-tracking velocimetry method was developed to measure three-dimensional flow fields around full-scale VAWTs in field conditions. Experiments were conducted at the Field Laboratory for Optimized Wind Energy (FLOWE) in Lancaster, CA, using six cameras and artificial snow as tracer particles. Velocity and vorticity measurements were obtained for a 2-kW turbine with five straight blades and a 1-kW turbine with three helical blades, each at two distinct tip-speed ratios and at Reynolds numbers based on the rotor diameter $D$ between $1.26 \times 10^6$ and $1.81 \times 10^6$. A tilted wake was observed to be induced by the helical-bladed turbine. By considering the dynamics of vortex lines shed from the rotating blades, the tilted wake was connected to the geometry of the helical blades. Furthermore, the effects of the tilted wake on a streamwise horseshoe vortex induced by the rotation of the turbine were quantified. Lastly, the implications of these dynamics for the recovery of the wake were examined. This study thus establishes a fluid-mechanical connection between the geometric features of a VAWT and the salient three-dimensional flow characteristics of its near-wake region, which can potentially inform both the design of turbines and the arrangement of turbines into highly efficient arrays., Version 2, currently under review

Purpose The purpose of this study is to enhance the thermal performance in the labyrinth channel by different ribs shape. The labyrinth channel is a relatively new cooling structure to decrease the temperature near the trailing region of gas turbine. Design/methodology/approach Based on the geometric similarity, a simplified geometric model is used. The k − ω turbulence model is used to close the Navier–Stokes equations. Five rib shapes (one rectangular rib, two arched ribs and two trapezoid ribs) and five Reynolds numbers (10,000 to 50,000) are considered. The Nusselt number, flow structure and friction factor are analyzed. Findings Nusselt number is tightly related to the rib shape in the labyrinth channel. The different shapes of the ribs result in different horseshoe vortex and wake region. In general, the arched rib brings the highest Nusselt number and friction factor. The Nusselt number is increased by 15.8 per cent compared to that of trapezoidal ribs. High Nusselt number is accompanied by the high friction factor in a labyrinth channels. The friction factor is increased by 64.6 per cent compared to rectangular ribs. However, the rib shape has a minor effect on the overall thermal performance. Practical implications This study is useful to protect the trailing region of advanced gas turbine. Originality/value This paper presents the flow structure and heat transfer characteristics in a labyrinth channel with different rib shapes.

The present study examines the turbulent flow characteristics in the vicinity of the leading edge of a vertical retaining wall structure embedded in a gravel bed. Conditions before and during the initial stages of local scour development were considered. To that end, three laboratory experiments were carried out: one with fixed boundaries as a reference case, a second one with an erodible bed, but immobile channel bank, and a third one characterized by an erodible channel bed and bank. Instantaneous and time-averaged flow features, and turbulence statistics associated with the three-component velocity fields, obtained with a stereoscopic particle image velocimetry system, were analyzed. Water surface examination determined that channel bank erosion alters flow behavior upstream of the retaining wall. This change is manifested through more frequent formation of eddies near the top corner of the junction between the upstream face of the protrusion and the channel bank. Time-averaged and instantaneous velocity vector fields demonstrate the presence of two counter-rotating vortices in the experiments with the fixed channel bank, one located near the junction of retaining wall and the channel bed and one away from it generated as a result of a strong downflow. The latter motion represents a section of a horseshoe vortex. During the channel bank erosion, however, these vortices are not as significant and persistent. The results also indicate that the coherency and magnitude of the streamwise vorticity field diminish as a result of scour. However, it was confirmed that local turbulent kinetic energy and shear stresses increase in the presence of scour due to enhanced local flow separation.

Local scour around bridge piers is one of the main causes of bridge failures. Study of local scour is very significant for the safe design of piers and other civil and marine structures. Despite the subject has been explored for many decades, the numerical developments have been very limited due to the complicated interaction of three-dimensional flow, sediment transport and fluid-particle interaction. In this work, a numerical model based upon the Reynolds Average Navier Stokes Equation (k-e) approach has been used for predicting the three dimensional flow (3D) around a bridge piers (square and cylinder piers), mounted on a flat and fixed bed. The main aim of this paper is the validation of the numerical model, based upon the previous experimental data. The CFD-numerical tool is proficient to qualitatively reproduce the flow characteristic for different pier shape and features around the pier, such as the upstream vortex (horseshoe vortex) and downstream vortex (vortex shedding in the wake). The outcome of this study can be used developing adequate numerical model to simulate the 2D and 3D turbulent flow past the square and circular piers, which are relevant case-studies for the marine and civil structures supported by pillars. The corresponding numerical results are in good agreement with those extracted from available experimental data.

In the present study, the subcritical flow past a generic side mirror on a base plane is investigated at the Reynolds number of 5.2×105 using delayed detached eddy simulation (DDES) turbulence model. Asides from the capability of capturing main features of the large recirculation vortex in the wake of the side mirror and the front horseshoe vortex, the accuracy of DDES estimation of recirculation length is significantly increased by over 20%, compared to the detached eddy simulation (DES) estimation using the same grid. And DDES prediction of pressure coefficient at the trailing edge of the mirror is in good agreement with the experiments, which is more accurate than both DES and large eddy simulation (LES) results. The results verify the capacity of DDES turbulence model to solve the turbulent flow around the side mirror. This is a key foundation for possible future study of full simulation of external flow field of vehicle.

Smoke-wire flow visualization is conducted carefully in a laminar junction to explore the physical behavior of laminar junction flows. The two-dimensional (2D) velocity fields in the 30° plane of a laminar junction flow are acquired by a time-resolved particle image velocimetry (PIV) system at a frame rate of 1 kHz, based on which the unsteady fluctuating pressure fields can be calculated by the multi-path integration method proposed in the literature (GAND, F., DECK, S., BRUNET,V., and SAGAUT, P. Flow dynamics past a simplified wing body junction. Physics of Fluids, 22(11), 115111 (2010)). A novel control strategy is utilized to attenuate the unsteadiness of the horseshoe vortices of the laminar junction flow, and the consequent effect on pressure fields is analyzed.

The influence of cubes-in-tandem on wall heat transfer in turbulent channel flow is investigated using complementary methods of temperature-sensitive paint (TSP) measurements and computational fluid dynamics (CFD). Three systems—a single cube and cubes-in-tandem at spacing-to-span-wise widths (S/d) of 3 and 4—were comparatively studied. For the single cube, a high level of turbulence in opposite-circulation vortices occurred for significant augmentation of convective heat transfer. For the tandem system at 3d, circulation was periodically advected downstream from two symmetric vortices, in alternating fashion; this mechanism was found to promote a high heat transfer rate across the leading face of the downstream cube. When the spacing was increased sufficiently, i.e., 4d, a new horseshoe vortex system occurred for substantial enhancement along the front face of the downstream cube. As such, the system at 4d promoted a distinct flow field in the wake region of the downstream cube, which was responsible for larger augmentation of the heat transfer area. The results showed that the heat transfer was enhanced in the inter-body space of the system at 4d as compared with the single cube. Behind the downstream cubes, the enhancement of heat transfer was pertinent to the unsteadiness of circulation vortices; meanwhile, the heat transfer monotonically decreased by the stream-wise distance for the single cube.

The present study numerically describes the nature of the arising boundary layer along an isothermal vertical plate, on which is mounted a bluff body. The investigation parameter is the cross-section shape of the bluff body, which includes a square, circular, and prismatic cylinders. To entirely embedded cylinder in the incoming boundary layer, the simulations include short cylinders with an aspect ratio fixed to unity. The cylinder location related to the leading edge of the plate is identified by considering laminar Grashof number, which experimentally is investigated in parallel work. Besides this, the experimental study of a square cylinder, confirms the reliability and accuracy of numerical simulation. As a result, by providing steady-state simulation, the presence of a complex vortex structure is proved. Besides, the effects of the cross-section shape of the cylinder on the dynamics characteristics of the vortex system include vorticity strength, size, and position are categorized. Finally, the significant effects of formed juncture flow on the three-dimensional thermal characteristics of arising free convective boundary layers along with the heated vertical plate are emphasized by a description of heat transfer coefficients. In particular, the importance of the frontal bluntness of cylinder in the field of thermal management is claimed, where the maximum value of the heat transfer coefficient for circular, prismatic, and square cylinders, respectively appears at the angular coordinates of 0 , 45 , and 90 degrees, which correspond with the location of cylinder edges.

Pile groups and complex piers have become more popular in the construction of bridge crossings due to economical and geotechnical reasons. The interaction of bridge piers of various structural solutions, which are in the wake one after another, leads to significant discontinuity and non-linearity of the flow between the piers, and also significantly complicates the process of bed sediment scour. This requires complex scientific research to determine the permissible bed sediment scour near bridge pier groups, since normative calculations do not always give a positive result. Results of experimental researches of formation and development of local and global scours near to bridge piers are submitted. Influence of an arrangement of two bridge transitions which are in a wake one after another, on physics of the formation process scour is shown. The scour before prismatic pier is caused by interaction of the horseshoe vortex structures with the sediment, down flow along the front surface of the pier and vortex systems that arise when the incoming flow is separated from the front faces of the prismatic pier. The scour before the three-row cylindrical pier in the form of the grillage is associated with the action of a horseshoe vortex structure that envelopes the grillage as a whole, horseshoe vortices that arise near each of the cylindrical piers of the grillage and the jet flow that occurs between the first piers of the grillage. With the mutual arrangement of two bridge crossings that are in the wake one after another, the local scour in front of the prismatic pier of the old bridge increases at supercritical flow velocities in shallow water and decreases at subcritical velocities in deep water.

The substantial adverse pressure gradient experienced by a turbulent boundary layer while approaching an endwall-mounted twisted turbine blade and caused the impending flow to separate three-dimensionally to form a dynamically active horseshoe vortex (HSV) system in the junction of the turbine blade with endwall. The large eddy simulations (LES) of the flow past a twisted turbine blade mounted on a curved endwall with periodic boundary condition in pitchwise direction is carried out for Re = 50000 to methodically investigate the HSV dynamics. The significant variations with Re in terms of mean flow quantities, heat transfer distribution, and coherent dynamics of turbulent HSV are shown in computed results. The HSV system consists of a multiple number of necklace-type vortices that are shed periodically at maximal frequencies. For high Re, we show that outburst of wall govern the instantaneous flow field, averaged vorticity affiliate with the growth of hairpin vortices that enclose around and dislocate the primary HSV. The time-mean endwall heat transfer is prevailed by two bands of high heat transfer which encircle the leading edge of the blade. The band of maximal heat transfer, occurs in the corner region of the juncture, while the secondary high heat transfer band (thin as compare to primary) develops upstream of primary band, in between primary and secondary bands a relatively low heat transfer region is identified.

Interaction of recirculating and mean flow downstream of a submerged gate may form significant vortex structures, which may affect the stability of the gate. Although these flow structures that appear in submerged hydraulic jumps received considerable attention in the literature, relatively less work was devoted to the analysis and suppression of the vortex structures downstream of a submerged gate. In this work, internal flow structure and vortex dynamics around a submerged gate were investigated through laboratory tests and large-eddy simulation (LES) using computational fluid dynamics (CFD). It is shown that numerical results obtained for mean velocity field are in good agreement with the experimental measurements. A helical vortex pair connected with a horseshoe vortex system was identified within the roller region using high-resolution numerical simulations. Damping performance of different types of anti-vortex elements placed on the downstream face of the gate are evaluated based on numerical studies. It is shown that the horizontal porous baffle mounted at an elevation below the free surface reduced the vortex magnitudes in the roller region by 26.8%. With the implementation of the proposed vortex breaker, lift forces acting on the gate lip were reduced by 9.4% and drag forces acting on the downstream face of the gate were reduced by 8.6%. Finally, in this study, we assess the performance of the vortex breaker under different flow conditions.

It was already mentioned in Chap. 3 that Saffman (Vortex dynamics. Cambridge University Press, Cambridge, 1992) quoted Kuchemann who said that vortices are the sinews and muscles of fluid motion.

The study of elliptical liquid jets in supersonic flow in a Mach 2.0 is performed numerically. The primary breakup process of the elliptical liquid jet is simulated for a Weber number 223, liquid/gas flux momentum 4.0. The aspect ratios of elliptical geometries are set to be 0.25, 0.5, 1, 2, and 5. The results show a remarkable difference in liquid jet disintegration morphology at different aspect ratios. Under supersonic crossflow conditions, the elliptical liquid jet shows more breakup characteristics than the round liquid jet. As the aspect ratio grows, the penetration depth decreases. The elliptical liquid jet with AR=0.25 has the largest penetration depth in all cases. Moreover, the round jet has a maximum spreading angle of 50.2°. The changing trends of the column breakup length both x direction and y direction are similar. The elliptical jet at a lower aspect ratio has a shorter breakup length due to the narrower windward area. The liquid jet has a pair of larger horseshoe vortex structure and a wider wake region at a higher aspect ratio. Two pairs of reversal vortex pairs with obvious characteristics can be observed in all the simulations.

A triangular-flapped wing planform, which produced two counter-rotating vortex pairs, was simulated using the horseshoe vortex method (HVM). A modeling method using discrete horseshoe vortex elements was introduced to model the geometrical discontinuities of the flap-tip juncture. The flap-tip modeling method allows the four-vortex system generated behind the triangular-flapped wing configuration to be simulated accurately. When the model was not applied, a strong vortex was generated at the wing-flap corner. The wake behavior and rolling moment induced by the wake vortices were investigated and compared with a reference experiment. The results of the simulation indicate that the quantitative values of the rolling-moment parameter can be estimated as well as the wake behaviors, even great distances. Even though only macroscopic wake behaviors can be simulated, due to limitations regarding viscosity and diffusion effects, these results support the theory that the HVM can simulate the initial stage of the instability of wake vortices in the inviscid region.

A computational model is developed using a delayed detached-eddy simulation to examine the various aspects of shock-wave/vortex interactions, in which the specific case of naturally formed bow shoc...

In this paper, the effectiveness of airfoil-shaped pier with and without a collar on local scour depth reduction is numerically investigated utilizing FLOW-3D model. The results show that on a constant T* = VT/D (V: velocity, T: time, D: pier width), increasing the width of the ballet of pier would result on the reduction of maximum scour depth and it would mitigate the scouring depth behind the piers. Also, because of lack of uplift vortices in using airfoil-shaped pier, there would be no scouring behind the piers. Utilizing collar on the airfoil-shaped pier would result in a reduction of maximum scouring depth in front of the pier as well and the uplift vortices behind the pier would reduce. Investigation of orientation discipline of the airfoil-shaped pier on flow route shows that the pier which is reversely placed in the flow direction (the keen part in front), will cause the horseshoe vortex to weaken and make the scouring to start from downstream. However, scouring caused by horseshoe vortex in front of the airfoil-shaped pier is strongly more than scouring caused by wake vortex in the rear of the pier.

International audience; Поступило в Редакцию 17 января 2019 г. В окончательной редакции 17 января 2019 г. Принято к публикации 24 апреля 2019 г. Проведено исследование взаимодействия пространственного сверхзвукового турбулентного потока газа с вдуваемой перпендикулярно со стенки звуковой струей, направленное на выявление и углубленное пони-мание механизмов образования вихрей за вдуваемой звуковой струей в сверхзвуковом натекающем потоке в зависимости от (отношение давления в струе к давлению в потоке). Решение трехмерных осредненных по Фавру уравнений Навье−Стокса, замкнутых k−ω моделью турбулентности, осуществляется с помощью алгоритма, построенного на основе ENO-схемы высокого порядка аппроксимации. Показано присутствие известных из ряда теоретических работ вихревых структур. Определены параметры нерасчетности, при которых появляется дополнительная пара вихрей, где одна пара возникает в результате взаимодействия замедленного потока струи за диском Маха и высокоскоростного восходящего внешнего потока струи, а вторая обусловлена взаимодействием потока над струей с бочкообразной структурой. В результате сравнительного анализа выявлены условия, при которых наблюдается четкая картина дополнительных роговых вихрей вблизи стенки в области за струей. Получена зависимость угла наклона головного скачка уплотнения от параметра нерасчетности. Установлено удовлетворительное согласие распределения давления на стенке перед струей в плоскости симметрии с экспериментальными данными. Ключевые слова: численное моделирование, сверхзвуковое течение, совершенный газ, пограничный слой, уравнения Навье−Стокса, параметр нерасчетности, ударная волна. Введение Течения высокоскоростных струй в поперечном по-токе обеспечивают эффективное смешивание топли-ва и окислителя, имеющего решающее значение для сверхзвукового горения. На данный момент известно большое количество экспериментальных [1-5] и теоре-тических [6-14] исследований, в которых достаточно хорошо изучен механизм образования ударно-волновой структуры струйного взаимодействия для умеренных параметров нерасчетности n (отношение давления в струе к давлению в потоке). Общую картину течения схематически можно представить следующим образом (рис. 1, a-пространственная картина, b-на линии симметрии): линия 1-головной скачок уплотнения, возникающий вследствие торможения набегающего по-тока перед струей, линии 2, 3-косой и замыкающий скачки уплотнения соответственно. Головной, косой и замыкающий скачки уплотнения, пересекаясь в одной точке, образуют λ-образную структуру. Буквами D и B обозначены диск Маха и бочкообразная структура в струе соответственно. Линиями 4 и 5 изображены хоро-шо известные два противоположно вращающихся вихря перед струей, появляющихся из-за большого градиен-та давления, создаваемого на стенке перед вдуваемой струей и, как следствие, отрыва пограничного слоя. На рис. 1, c схематически иллюстрируется вихревая структура за струей, которая, как известно, вносит существенный вклад в смешение топлива и окислите-ля. Здесь линией 6 представлен вихревой след, 8-это общеизвестная противоположно-вращающаяся пара вихрей в самой струе, образованная прогибом струи и конвекцией поперечного потока, также здесь приведен подковообразный вихрь 7. Однако в работе [9] в результате численного модели-рования течения с параметром нерасчетности n = 282 и в расчетах [13], проведенных с параметрами нерас-четности в диапазоне 10 ≤ n ≤ 50, выявлено наличие дополнительных пар вихрей за струей, которая схемати-чески также иллюстрируется на рис. 1, c. В этой картине новыми являются вихревые структуры 9 и 10, где пара вихрей 9 возникает за счет взаимодействия струи, прохо-1513

The flow-induced lateral vibration phenomenon of the terminal sensitive bullets (TSB) when it is dispersed by the airborne distributor is taken as the research background. Based on the Fluent, the flow around a rotating short cylindrical TSB (L/D < 1) is simulated and analyzed varying with relative rotation velocity at high Re number (1×105 ≤ Re ≤ 3×106). The simulation results show that the flow field structure of the short cylinder with two free ends is different from the symmetry of the short cylindrical flow field with one free end, and there is no horseshoe vortex. Compared to the long cylinder with double free ends, the Cd of the short cylinder is more sensitive to the change of Re. With the increase of Re, the Cd of the short cylinder decreases, and the value is between the infinite cylinder and the sphere in the non-critical region. When the short cylinder rotates at the angular velocity ω, the top vortex bends and deforms to a ‘C’ shape on the leeward side where the fluid is accelerated. Due to the periodic disturbance of the detector, the aerodynamic coefficient of the rotating TSB is periodically vibrated. In a single cycle, the waveform of the cd shows a ‘W’ shape, and the waveform of the cl is ‘M’.

The subject of this study is the discussion of the dissipation of turbulent kinetic energy and its Reynolds number scaling in front of a wall-mounted cylinder. We employed highly resolved Large-Eddy Simulation and ensured that the computational grid was fine enough to resolve most of the scales. A perceptible fraction of the total dissipation is modeled. However, this fraction - about one third - is small enough so that the total dissipation suffers only marginally from some potential shortcomings of the turbulence model. Individual terms of the pseudo dissipation tensor and their Reynolds number scaling are discussed and compared. This tensor and thus the turbulent small scale structures are not isotropic at the Reynolds numbers investigated. Furthermore, the near-wall anisotropy under the horseshoe vortex is likely to persist to larger Reynolds numbers as it can be linked to a flapping of the near-wall layer. The turbulent length scale shows a strong spatial variability. In the region of the vortex system in the cylinder front, the distribution reveals a similar shape as the one of the turbulent kinetic energy and its amplitude is in the order of magnitude of the cylinder diameter. In contrast to the region dominated by the approach flow, the turbulent length scale is independent of the Reynolds number in the region dominated by the vortex system. Even though the flow investigated is in non-equilibrium, common a priori estimations and scalings of the Kolmogorov length scale based on macro scales give satisfying results.

An experimental study of film cooling with one row of holes was conducted using fast-response pressure-sensitive paint (fast-PSP) and a high-resolution camera. The film-cooling effectiveness behind a single row of holes was measured for blowing ratios (M) ranging from 0.135 to 1.5. The main attention was focused on unsteady behavious of the film-cooling effectiveness, subjected to interaction between the neighbouring jets. Distribution of the time-averaged film-cooling effectiveness determined the jet lift-off beyond M = 0.5, while the interaction between the neighbouring jets could be recognized at M ≥ 1. Subsequently, the instantaneous film-cooling effectiveness and its space correlations were analysed and discussed in terms of flow structures like counter-rotating vortex pair (CRVP) and horseshoe vortex. Three types of film-cooling effectiveness oscillations were observed: for a low blowing ratio (M = 0.135), a strong oscillation were observed at the cooling hole area and a synchronised oscillation downstream of the hole; for moderate blowing ratios (M = 0.35, 0.52, 0.81), a sweep oscillation was observed downstream of the hole; for high blowing ratios (M = 1.0 and 1.5), an irregular oscillation was observed downstream of the hole. Further clarification of the unsteady film-cooling effectiveness coupled with the energetic flow structures was made using the proper orthogonal decomposition (POD) analysis, which showed three POD intensity spectra corresponding to different oscillating structures. The lowest blowing ratio (M = 0.135) showed the highest intensity level of the first-order mode (84%) and the steepest slope Spectra curve of the POD eigenvalues. The moderate blowing ratios (M = 0.35, 0.52 and 0.81) showed the lowest intensity levels of the first-order mode (21–28%) and the most gentle slope Spectra curve of POD eigenvalues. For high blowing ratios (M = 1.0 and 1.5), whether referring to the intensity of the first mode or the slope of the intensity Spectra curve, all were between the lowest and moderate blowing ratios. Finally, for three typical blowing ratios (M = 0.135, 0.35, and 1.5), the POD modes demonstrated the separate effects of an unstable synthetic low-speed region, a CRVP, and a highly developed hairpin vortex.

Junction flows are subject to an intense adverse pressure gradient and three-dimensional separation when encountering a wall-mounted obstacle. A dynamically rich horseshoe vortex system is formed in this region. In this study the junction flow at the interaction of a wing and a flat plate is investigated. The numerical modelling is carried out using the three-dimensional large eddy simulation (LES) approach at the Reynolds number Re = 1.15×105 based on the wing’s maximum thickness T and the free stream velocity Uref. The comparison with the experimental results shows that the numerical simulations fairly accurately reproduce the phenomenon under study. The dynamic mode decomposition (DMD) of the resolved flow field is employed to obtain the coherent dynamics of the flow. To clearly demonstrate the oscillation characteristics and the horseshoe vortex structures of junction flow the velocity field in the plane of symmetry is decomposed with eduction of two dominant DMDmodes. These two DMDmodes are reconstituted and developed, together with the mean flow mode to explain the latent dynamics. Mode 1 reveals the merging of the horseshoe vortices and mode 2 is responsible for the process of fission and stretching.

City planning can have a significant effect on wind flow velocity patterns and thus natural ventilation. Buildings with different heights are roughness elements that can affect the near- and far-field wind flow velocity. This paper aims at investigating the impact of an increase in building height on the nearby velocity fields. A prototype urban setting of buildings with two different heights (25 and 62.5 cm) is built up and placed in a wind tunnel. Wind flow velocity around the buildings is mapped at different heights. Wind tunnel measurements are used to validate a 3D-numerical Reynolds averaged Naviers–Stokes model. The validated model is further used to calculate the wind flow velocity patterns for cases with different building heights. It was found that increasing the height of some buildings in an urban setting can lead to the formation of large horseshoe vortices and eddies around building corners. A separation area is formed at the leeward side of the building, and the recirculation of air behind the building leads to the formation of slow rotation vortices. The opposite effect is observed in the wake (cavity) region of the buildings, where both the cavity length and width are significantly reduced, and this resulted in a pronounced increase in the wind flow velocity. A significant increase in the wind flow velocity in the wake region of tall buildings with a value of up to 30% is observed. The spatially averaged velocities around short buildings also increased by 25% compared to those around buildings with different heights. The increase in the height of some buildings is found to have a positive effect on the wind ventilation at the pedestrian level.

A simple model of the flowfield induced by an inclined jet into an incompressible crossflow is proposed. In general, such a jet generates an asymmetric pair of vortices, with a larger one farther f...

Three-dimensional numerical simulations, for confined flows and unconfined flows, have been carried out to study the Karman vortex street inversion in the wake of a square cylinder. This paper is aimed to analyze the cause of the vortex inversion and to investigate the physical mechanisms. As two independent factors for the inversion, the wall confinement and the incoming flow conditions have been proved in a more rigorous way. It is shown that the interaction between the primary vortex and the incoming flow or the wall vortex layer is the fundamental cause. In order to compare the thermal transport phenomenon between the inversion and non-inversion cases, the top wall of a channel is kept at the free stream temperature and the bottom wall is set heated, while the cylinder is maintained adiabatic. The results indicate that the inversion phenomenon is not good for the heat transfer. Additionally, the effects of streamwise magnetic field on the vortex street inversion has been considered.

Cavitating tip-leakage vortices appear in several hydrodynamic flows such as marine propellers or Kaplan turbines. Cavitating computations are a challenging topic since several keys issues are an ongoing work such as the definition of a universal mass source term. The present study focuses on the computations of the tip-leakage vortex including the gap between the blade tip and the side wall. Two computations are performed, one without cavitation and a second one with cavitation. In both cases, the results are compared with experimental data. The cavitation influence is investigated by comparing the cavitating and the non-cavitating cases. A particular attention is focused on the vortex core trajectory, the vorticity field and the vortex core identification. It is shown that, compared to the non-cavitating case, cavitation leads to a vortex trajectory closer to the suction side and the side wall, which can be of importance regarding the cavitation erosion. Furthermore, cavitation modified the vorticity field in the vortex core region. The main feature is a misalignment between the high vorticity region and the cavitating region, which opens a discussion regarding the definition of the vortex core.

The objective of this paper is to investigate ventilated cavitating flow structures with special emphasis on vortex shedding dynamics via combining experimental and numerical methods. In the experiments, the high-speed video and time-resolved particle image velocimetry (TR-PIV) technique are used to observe ventilated cavitating patterns, and to measure the flow velocity and vorticity fields. The numerical simulation is performed by CFX with large eddy simulation (LES) model to capture the unsteady cavity shedding process, and the corresponding velocity and vorticity dynamics. The results show that the flow patterns can be classified into two principally different categories: structures mainly with vortex shedding (namely Benard–Karman vortex street; Benard–Karman vortex street with vortex filaments and Aligned vortices) and relatively stable structures (namely Aligned vortices with Re-entrant jet; Re-entrant jet and Stable supercavity). For the structures mainly with vortex shedding, the Strouhal number St corresponding to vortex shedding frequency and ratio h/λ corresponding to vortex streets are significantly different in variable ventilated cavitating regimes: St and ratio h/λ increase with enhancement of gas entrainment coefficient Qv for the Benard-Karman vortex street, and then St declines gradually for Benard-Karman vortex street with vortex filaments and Aligned vortices, but ratio h/λ declines dramatically for the above both patterns. In addition, the influences of Qv on the velocity and vorticity distributions have also been investigated. The proper orthogonal decomposition (POD) analysis of PIV measurements is used to characterize the coherent large-scale flow unsteadiness of velocity fields. It demonstrates that the ventilated cavitation plays an important role in the first mode pairs to mainly affect the vortex shedding in the wake. Moreover, the vorticity transport equation is applied to illustrate the influence of ventilated cavitation on the vorticity distribution. It can be found that the associated vortex dilatation term and baroclinic torque term are important mechanisms for the complicated change of vortices.

A large eddy simulation (LES) of a fully appended SUBOFF model was performed by the Boundary Data Immersion Method (BDIM) with the Reynolds number of 1.2 × 107. Numerical simulation is carried out through Fortran-based code and the geometric structure used in this paper is an idealized submarine (DARPA SUBOFF, with appendages). The computational uniformly distributed orthogonal grids consist of approximately 108 million nodes and are used to capture all essential flow structures. The pressure coefficients and streamwise velocity distribution obtained by the large-eddy simulation (LES) are in good agreement with the experimental data. The objective of this paper is to evaluate the ability of BDIM to predict the flow over axisymmetric hull, to investigate the evolution of the junction and tip flows on the body of the SUBOFF. Three different types of large-scale vortex structures were found around the sail, including horseshoe vortex, hairpin vortex and necklace vortex. The different vortex identification methods, namely, ω criterion, Q criterion and Liutex method, are used to capture and analyze the formation mechanism of various vortex structures. Meanwhile, by extracting the rotation and shear relative parameter e around the sail, it can be found that the rotation is dominant in the vortex distribution profile.

Strong secondary flow results in substantial aerodynamic loss for highly-loaded turbine. Accurate prediction of the complicated flow structures proposes challenges to the widely used Reynolds Average Navier-Stokes (RANS) approach. This work employs the hybrid RANS/Large Eddy Simulation (LES) method to study the unsteady flows for a highly-loaded turbine blade, with both flat endwall and optimized contoured endwall. Evolution of the unsteady flows in the endwall region is analyzed, with emphasis on the loss generation mechanism. Results show that for the flat endwall, the horseshoe vortex system is highly unsteady and is a significant source of unsteadiness in both the passage and the wake region. It contributes to the unsteady passage vortex, also the earlier breakdown of the trailing edge shedding vortex. The Probability Density Function (PDF) histogram of velocity in the wake region is bimodal, implying the perturbations from two mechanisms. For the contoured endwall, the unsteady evolution of the horseshoe vortex is blocked, which results in significantly reduced unsteadiness, also the merge between the horseshoe vortex with the passage vortex is prevented. Effect of the flow unsteadiness on the loss generation is assessed based on the entropy generation rates contributed by the time-averaged flow and the fluctuations. The effect of unsteadiness is two-fold: unsteady perturbations trigger the vortex breakdown into small-scale structures and thus weakened wake velocity deficit and loss generation; however, in both the passage and the wake region the entropy generation by the fluctuations are remarkable. For the contoured endwall, due to the reduced flow unsteadiness, loss generation contributed by the fluctuations are much smaller compared to the flat endwall. The results highlight the importance of including the loss generation by the fluctuations, also a possible mechanism to reduce the secondary loss by attenuating the flow unsteadiness with the contoured endwall.

This study aims to investigate experimentally the influence of rounding corners (r) as well as aspect ratio (AR) on the flow structures of a surface-mounted finite cylinder. The cylinders with sharp (r* = r/D = 0) and rounded corners (r*=0.167, 0.25 and 0.5) and aspect ratio or height-to-width/diameter ratio (AR = H/D) between 2 and 7 are utilized. The experiments are based on the five-hole probe and hot-wire measurements as well as the oil flow visualization. Wake measurements are made in an open return wind tunnel at the Reynolds number, Re = 1.6 × 104, where Re is defined based on the side width/diameter (D) of the cylinder cross-section and the freestream velocity. It is found that r* and AR have significant effects on the flow structure from the perspective of wake topology, strength of streamwise vortices, and vortex shedding frequency. For all r* considered, the wake is characterized by a quadrupole type (both the tip and base vortices are present) at AR = 7, while a dipole type occurs for AR = 2 and 4 (the base vortices are absent). The strength (circulation) of the streamwise vortex structures is affected by r*. For all AR examined in the present study, the strengths of tip and base vortex structures decrease with increasing r*. The oil flow visualization demonstrates that the features of the horseshoe vortex are sensitive to r* and AR. With increasing r*, the location of the separation line moves downstream and the distance between horseshoe vortex legs decreases. Velocity measurements reveal that the downwash flow enhances with increasing r*. It is also found that the Strouhal number increases progressively by 60% as r* increases from 0 to 0.5, regardless of AR.

The evolutions of aircraft wake vortices near ground in stable atmospheric boundary layer are studied by Large Eddy Simulation (LES). The sensitivity of vortex evolution to the Monin-Obukhov (M-O) scale is studied for the first time. The results indicate that increasing stability leads to longer lifetimes of upwind vortices, while downwind vortices will decay faster due to a stronger crosswind shear under stable conditions. Based on these results, an empirical model of the vortex lifetime as a function of 10-m-high crosswind and the M-O scale is summarized. This model can provide an estimate of the upper boundary of the vortex lifetime according to the real-time crosswind and atmospheric stability. In addition, the lateral translation of vortices is also inspected. The results show that vortices can travel a furthest distance of 722 m in the currently-studied parameter range. This result is meaningful to safety analysis of airports that have parallel runways. Keywords: Aerodynamics, Aircraft, Aircraft wake vortex, Large eddy simulation, Stable atmosphere boundary layer

Passive mass transfer enhancement from the surface of a liquefying substance using Lateral Sweep Vortex Generators (LSVG) placed in high-speed flow is presented. Numerical simulation of three-dimensional turbulent compressible flowfield involving species transport has been carried out using Advection Upstream Splitting Method (AUSM) scheme based Finite Volume solver. A temperature dependent mass efflux boundary condition has been developed and implemented in the computational procedure for updating the boundary mass flux. Computational procedure has been validated using the experimental wall pressure profile reported for a similar vortex generator placed in high speed flow and could capture the complex flow features resulted by the vortex-boundary layer interactions. Convective mass transfer of species is found to get improved in wake region of the LSVG by the horseshoe vortex and further get transported downstream by the counter-rotating vortex pair. Extensive numerical simulations have been carried out with several lateral sweep angles of LSVG to explore the role of vortices in promotion of the convective mass transfer. It has been observed that the mass efflux enhances with increase in sweep angle of the vortex generator due to the vorticity augmentation. Analysis of the vortex trajectories could figure out the influence of vortex interactions leading to the peak mass efflux. Further, an exponential-power law based correlation between relative Sherwood number and relative streamwise vorticity has been developed.