Spray Cloud Research Articles

Measurement of electric fields of charged spray clouds of conductive liquids in free space and in a conductive vessel

The process of spraying liquids generated electrical charges. The question therefore arises as to whether this electrostatic charge represent an ignition hazard when an explosive mixture is present. This hazard occurs when cleaning vessels, in which an explosive mixture is formed by residues of easily flammable liquids or the cleaning medium itself. Although measurement techniques and methods exist for detecting this electrostatic charging process, they have not been sufficiently scientifically proven. The Chilworth JCI 131 adverse conditions field meter is to be used to measure the electrostatic charging of sprayed liquids. It shall be validated by measuring the electric field strength of a flat spray water jet in low-pressure range (8 bar) charged by contact charging and accumulation of free electrons of a commercial, insulated arranged electrostatic spraying system (up to - 90 kV). A flat-jet nozzle is selected which atomizes the spray jet, which serves as the measuring surface, sufficiently large. This arrangement is further investigated in a 1 m3 stainless steel IBC. The investigations presented are part of a project aiming to extend the scope of the German Technical Rules for Hazardous Substances (TRGS) of TRGS 727, which regulate avoiding ignition hazards resulting from electrostatic charging. The aim is to reach an understanding that allows provisions for safe cleaning of “small” and “medium-sized” containers up to 50 m3. This project is funded by DGUV (German Social Accident Insurance) and partners from the industry.

An analytical model of final average droplet size prediction of wave spray cloud

This study introduces an analytical model to predict the final average droplet size within a spray cloud that is formed due to wave interactions with marine objects. The process of spray cloud formation from wave impact involves several complicated processes, and each of these phenomena should be taken into account when considering an analytical approach. Following this process-based approach, the model first considers the wave characteristics and relates wave properties to the maximum impact pressure also considering the effect of air entrapment occurrence. Secondly, the maximum impact pressure is correlated empirically to the maximum wave run-up velocity. Finally, wave run-up velocity is linked with water sheet breakup models, which leads to the prediction of the final average diameter of ligaments and droplets. The prediction model is compared with experimental measurements from experiments conducted in a tow tank to form a spray cloud due to wave impact with two lab-scale models. Several measuring techniques such as image processing, bubble image velocimetry (BIV), and digital particle image velocimetry (DPIV) methods were implemented to measure the physical quantity of each phenomenon during the event of wave interaction. The effects of initial wave characteristics, the geometrical parameters of the impact condition and water sheet thickness at the moment of impact, on the final average droplet diameter were investigated. A sensitivity analysis of most of the principal parameters was performed to show the high veracity of the prediction model.

Effect of different parameters on mixture formation and flow field in simulations of an evaporative spray injection test case

Direct injection plays an important role in the efforts to increase efficiency of modern engines, and the correct evaluation of the velocity and fuel mixture fraction fields is crucial for modeling combustion in fuel sprays. Therefore, a computational study has been performed to assess the effect of different parameters on the mixture formation and flow field in the simulation of a single jet of the engine combustion network (ECN) “Spray G” evaporative gasoline injection test case. The Lagrangian particle tracking (LPT) approach was tested within both Reynolds-averaged Navier–Stokes (RANS) and large eddy simulation (LES) frameworks, and the varieties were compared. Additional parameters that were considered include mesh resolution (0.75, 0.50, and 0.25 mm) and droplet breakup (Reitz–Diwakar, Reitz–KHRT, and Pilch–Erdman), as well as stochastic turbulent dispersion (O’Rourke) and stochastic collision (O’Rourke) models. Experimental penetration length data from both liquid and vapor phases were used to validate the 54 simulations performed within this study. Then, a series of analyses were performed to weigh the effect of each isolated parameter on the outcome of the simulations. Finally, three additional simulations were conducted to study specific issues of LES in fuel spray modeling. In this way, this study was able to make a qualitative comparison of the evaporative spray cloud shapes and the evaluation of spray statistics in terms of the iso-octane mixture fraction and droplet/slip velocities.

Prediction of droplet size and velocity distribution for spray formation due to wave-body interactions

This study addresses the development of a statistical tool for predicting the distribution of the size and velocity of droplets in spray caused by the interaction of waves with a marine object. The Maximum Entropy Principle (MEP) is a statistical tool that allows the prediction of a probability distribution that is consistent with information from the input system. The prediction satisfies constraint equations covering the conservation of mass, momentum, and energy. The velocity distribution of droplets is Gaussian in shape. The effect of a drag force on both the liquid sheet that is formed from the wave impact as well as the downstream distribution of droplets was considered in this simulation. The examination of the mechanisms of turbulence diffusion in a wave at the moment of impact with an object provides a logical, analytical relationship between the wave flows and a spray cloud formation after impact. The model prediction is compared with the experimental data of spray-cloud formation due to wave impact from a lab-scale model, and is found to be in good agreement. The prediction model is then applied to the full-scale model based on the data from previous field observations to predict the droplet size and velocity distributions of spray cloud due to the wave interactions with the vessel.

Effects of Mosquito Control Adulticides on Sterile Cochliomyia hominivorax (Diptera: Calliphoridae).

Effects of mosquito control adulticides on sterile screwworm flies, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae), were investigated via bottle bioassays, outdoor cage tests, and exposure to treated vegetation. In bottle bioassays, 43 μg of permethrin via dilution of Evoluer, 474.56 μg of malathion via dilution of Fyfanon, and 25 μg of naled via dilution of Dibrom Concentrate were used to challenge screwworm flies. Permethrin was more toxic to screwworm flies than was malathion, which was more toxic than naled. On succeeding days, permethrin was still lethal to the flies, whereas malathion and naled were less toxic. During outdoor cage trials, screwworm mortality declined as distance from the spray truck increased. Sterile screwworm flies were killed by lower concentrations of permethrin needed to kill black salt marsh mosquitoes, Aedes taeniorhynchus (Wiedemann) (Diptera: Culicidae). Flies exposed to treated vegetation taken from the path of the spray cloud died more quickly than did flies exposed to leaves taken 5 ft inside the canopy. Fly mortality increased as volume mean diameter of droplets increased. In spite of the toxicity of Evoluer to screwworm flies, aspects of their biology make it unlikely that mosquito control operations would affect released flies.

3-D trajectory analysis of wave-impact sea spray over a marine vessel

Limited data is available about distributions of size, velocity and the probability of the existence of droplets impinging on cold marine vessel surfaces. Droplet sizes and velocities determine the flow rate of sea water impinging on freezing surfaces on marine vessels. This study develops a new three-dimensional model, employing the characteristic size-velocity dependence of droplets, to calculate droplet trajectories over a Medium-sized Fishing Vessel (MFV). The trajectory model employs the wind and vessel velocities and calculates forces exerted on droplets to determine their paths over the vessel. Results show that the top of a spray cloud forms a concave surface between the foremast and the front side of the superstructure. As spray travels over the deck, larger droplets fall on the deck or return to the sea and smaller droplets become aligned with the wind. The maximum height of the spray cloud, wet heights of the foremast and wet heights of the front side of the superstructure are compared to previous data in the literature, which are in good agreement with field observations and past numerical solutions.

Quantitative Analysis of Aedes albopictus Movement Behavior Following Sublethal Exposure To Prallethrin.

The pyrethroid prallethrin, an AI in DUET™ (Clarke Mosquito Control, St. Charles, IL), is widely marketed ultra-low volume (ULV) mosquito adulticide. Volatilized prallethrin is intended to stimulate mosquito flight, increasing its adulticide effectiveness. However, field tests using volatilized prallethrin have not produced significant differences in mosquito trap catches, leading to questions regarding prallethrin's behavioral impact efficacy. Thus, we conducted laboratory tests of prallethrin's effect on flight behavior of adult female Asian tiger mosquitoes, Aedes albopictus. Mosquitoes were divided into 3 groups: untreated control, exposed to volatilized prallethrin, and exposed to a liquid spray calibrated to simulate a ULV application at label rates. After exposure, mosquito behavior in an airstream of 0.5 m/sec was recorded and analyzed using motion-tracking software. No significant differences in flight behavior were found between the control and treated mosquitoes exposed to volatilized prallethrin. The ULV-sprayed mosquitoes exhibited a significant increase in the number of flight events, the turning frequency, overall movement speed, and flight speed compared to the control-a significant difference in locomotor stimulation response that would increase exposure to a ULV spray cloud. However, our results showed that volatilization alone was insufficient to increase ULV efficacy in the field and suggested that incorporating a more volatile flight stimulant into ULV adulticides would provide a measurable improvement in mosquito control.

Aerial electrostatic spray deposition and canopy penetration in cotton

Daylight visible fluorescent dye (10% v/v) mixed with water was aerially applied on mature field cotton with electrostatic and rotary atomizer nozzles. The spray rates for the electrostatic and rotary atomizer nozzles were 9.4 and 28 L/ha, respectively. Images of spray droplets on cotton leaves were digitally analyzed with ImageJ software. Charged spray cloud increased deposition nearly two to three times on adaxial and abaxial surfaces, respectively, of top canopy leaves compared to uncharged spray. Canopy penetration of the spray into the lower layers of the plant foliage was unaffected by spray application method.

Laboratory Measurements on the Sensitivity of Evaporation Rate of Droplets Inside a Spray Cloud

<abstract> <b><sc>Abstract.</sc></b> This article summarizes additional experimental data collected regarding the evaporation rate of water droplets stacked on several threads, positioned downwind of one another, and strengthens previously published results regarding droplet evaporation rates inside a spray cloud. Here, the effect of evaporating water droplets upwind of other droplets is examined, along with changes in tunnel speed, temperature, and relative humidity on droplets positioned on single threads. These results further quantify the wet bulb temperature depression felt by droplets within a spray cloud, along with the effect of the Sherwood number, and are used to enhance the ability of AGDISP to make accurate model predictions for droplets released from spray nozzles.

Water breakup phenomena in wave-impact sea spray on a vessel

Breakup of water in wave-impact sea spray is examined in this paper. The formation of a spray cloud, caused by high energy striking of a sea wave on the bow or hull of a marine vessel, is dependent on the water breakup phenomena and droplet trajectories. The Weber and Reynolds numbers are key parameters defining the thresholds at which breakup begins. The model uses “stripping breakup” and “bag breakup” characteristics to demonstrate the breakup phenomena. A combined breakup model with droplet trajectories is developed in this paper to predict the extent of the breakup phenomena. The governing equations of breakup and trajectories of droplets are solved numerically. Stripping breakup occurs from the beginning of the breakup phenomenon and finishes in front of the vessel. Bag breakup completes the stripping breakup to create stable droplets with constant diameters. A sensitivity analysis evaluates the response of the model to various ranges of initial conditions. Numerical results have reasonable agreement with the size-velocity dependence characteristics at the tip of the bow. The extent of the spray as well as wet heights, obtained by the numerical solutions, are consistent with field observations reported for a Medium-sized Fishing Vessel (MFV).

Influence of a Young Pinus radiata Canopy on Aerial Spray Drift

Abstract. An experiment was undertaken to test the hypothesis that AGDISP, a mechanistic model that simulates the landing position of droplets aerially released for pesticide application, overestimates downwind airborne spray concentrations by not accounting for the turbulence generated within the canopy sublayer. AGDISP is used by pesticide regulators in many parts of the world to quantify exposure from aerial pesticide spraying as part of an assessment of risks to public health and the environment. Using a novel design, airborne spray drift was measured in a 3.2 m high radiata pine plantation, 65 m downwind from the aerial spray flight line, using a small circular sampling array. The spray sampling array consisted of a central 10 m high mast plus a set of 16 secondary masts distributed evenly around a circle with a radius of 5 m from the central mast. All spray applications were made with a Bell Jet Ranger using a spray mix of water plus a fluorescent tracer and a droplet spectrum with a volume median diameter of 101 µm. A single treatment comprised six passes along the flight line, and there were 28 replications. Airborne spray was sampled with both rotorods and artificial foliage placed at four heights on the central mast, ranging from approximately half canopy height to 3 times canopy height. The secondary towers sampled airborne spray using the same collectors placed at just above canopy height and at half canopy height. Other measurements included leaf area distribution, prevailing meteorological conditions, and turbulence using sonic anemometers. Backscatter LiDAR was used in an attempt to quantify the height and density of the spray cloud in the vicinity of the central mast. Rotorod and artificial foliage deposition values were highly correlated, giving confidence in the sampling approach. Neither wind speed nor release height had a significant effect on airborne spray flux in the 0 to 10 m zone, but results were complicated by a spurious negative correlation between wind speed and spray release height. The lack of dependence of deposition on wind speed in this experiment is surprising but is explained both by the variance in the data as well as the physics of small droplet movement in the atmosphere. At the individual sample level, measurements of airborne spray using either rotorods or artificial foliage were poorly correlated with AGDISP predictions. However, when data were averaged across replications, there was a very strong correlation between measurements and AGDISP data, even though in absolute terms, and as hypothesized, AGDISP significantly overpredicted the quantity of airborne spray. As indicated from a comparison with measured deposition, the backscatter LiDAR appeared effective in describing the spray cloud profile, and it suggested a total spray cloud profile that was more complex than the AGDISP model prediction. Keywords: Aerial application, AGDISP, Canopy deposition, Pesticides, Spray drift.

Laser diagnostics for urea-water solution spray characterization

In this study, we summarize the laser techniques used for urea-water solution (UWS) spray characterization at the Institute of Heat Engineering (ITC), Faculty of Power and Aeronautical Engineering at Warsaw University of Technology. In presented studies several techniques for both, global and local spray characterization were used. Shadowgraphy-based long distance microscopy was used to visualize individual droplets and primary breakup. High speed imaging of Mie scattering (scattering on the gas-liquid interface) signal was used for global spray characterization. Combination of LIF (Laser Induced Fluorescence) and Mie scattering allowed to determine qualitative droplet size distribution across the whole spray cloud. The structured illumination technique used to modulate laser light sheet allowed to minimize the effects of multiple scattering in detection of Mie signal, what indicated huge potential of this technique in characterization of UWS sprays. The results presented here prove the importance of laser diagnostics in SCR systems development.

Spray Tip Effect on Glufosinate Canopy Deposits in Palmer Amaranth (Amaranthus palmeri) for Pulse-Width Modulation versus Air-Induction Technologies

<abstract> Five nozzle tip treatments included nozzle tip designs and selected use of blended pulse-width modulation (bPWM), with tip selections based on a maxim of reduced spray drift potential, either through droplet size classification or spray entrainment of dual sprays. Spray nozzle technologies prioritized for this study included bPWM of pre-orifice tips in various configurations of single and dual tips, and air-induction tips operated in constant (non-bPWM) mode. A self-propelled sprayer equipped with a 30.5 m boom and bPWM applied glufosinate-ammonium herbicide simultaneously through the five different spray nozzle tip treatments. Ambient wind veleocities ranged from 3.1 to 4.1 m s^-1during application. Herbicide deposits on leaves and water-sensitive paper (WSP) coverage, spot density, and droplet size characteristics at top and middle canopy locations in Palmer amaranth were used to compare nozzle tip treatments. Treatment 1 (pre-orifice tips, bPWM and non-bPWM) produced significantly greater herbicide deposits than all tips except Treatment 2 (pre-orifice tip, bPWM). The latter was not significantly different from all other tips. The numerically lowest deposit level, based on the overall means, was produced by Treatment 5 (air-induction deflector tip, non-bPWM), although the leaf deposit was not significantly different from most tips. Deposits of glufosinate-ammonium for top canopy locations were greater than middle canopy location deposits for a given nozzle tip treatment. Summation of deposits across locations sometimes exceeded the application rate of 4.5 μg cm^-2, attributed to spray cloud momentum due to the application speed of 24 km h^-1. The addition of more weed plants or crop plants could possibly alter spray cloud momentum or serve as interceptors of droplets at the expense of deposit levels on Palmer amaranth. Glufosinate-ammonium leaf deposits were inversely proportional to and significantly correlated with canopy coverage of the ground, which supported this hypothesis. The highest mean WSP coverage occurring at top location for Treatment 1 was significantly greater than the mean WSP coverage at top locations for Treatment 4 (air-induction extended-range tip, non-bPWM) and Treatment 5, and greater than mean WSP coverages for all tip treatments at middle locations based on p-level observations. The highest mean WSP spot deposit for the top location of Treatment 1 (57.9 cm^-2) was significantly greater than the mean WSP spot deposits for all other tip treatments and canopy locations. A wide range of droplet sizes resulting from the entrainment of a Fine spray into an Extremely Coarse spray may have contributed to high values of coverage and spot deposit for Treatment 1. In conclusion, use of a pre-orifice nozzle tip with bPWM plus a pre-orifice nozzle tip in constant (non-bPWM) mode that produced contrasting droplet sizes for spray entrainment between the two tips provided a means to increase glufosinate-ammonium deposits on leaves and increase coverage and spot density on WSP. On the other hand, Y-adapter mounted pre-orifice tips with bPWM and separate air-induction nozzle tips (extended-range and deflector designs) operated as non-bPWM applications did not result in high levels of glufosinate-ammonium deposits on leaves and did not result in high levels of coverage and spot density on WSP.

Droplet size and velocity distributions of wave-impact sea spray over a marine vessel

The spatial distribution of droplets in a spray cloud created by wave-impact sea spray and the distribution of their sizes and velocities over a vessel deck are investigated. Existing mono-size and mono-velocity models of sea spray are not accurate enough for modelling marine icing phenomena. Wave-impact sea spray creates numerous droplets in front of and around a vessel. Droplets are the result of sheet and droplet breakup of sea water. The velocity-size dependence of the resultant droplets causes the creation of various sizes and velocities of droplets. A droplet trajectory method employs the velocity-size dependence of the droplets to find their spatial distributions in the cloud of spray over the vessel deck. Drag and body forces overcome the initial velocities of the droplets, and consequently, they follow the wind and gravitational directions. The motion of the droplets affects the shape and extent of the spray cloud over the vessel. A numerical scheme is used to find the distribution of sizes and velocities of the droplets over a vessel. Results show that neither the smallest nor the largest droplets reach the maximum height. The medium-sized droplets can reach the maximum height of the spray cloud. As the spray cloud travels over the deck, the droplet velocities become almost the same. Comparing the numerical results with field observations shows that the predicted results are consistent and have reasonable agreement with the field measurements.

Waterfall Simulation with Spray Cloud in different Environments

This paper reports the simulation of waterfall including spray cloud in different environments. Visualization of liquid behavior on physically based simulation is one of the most challenging issues in computer graphics, especially the simulation of waterfall needs huge amount of computer resources such as calculation power and much memory. Then, we have been trying to visualize the waterfall simulation by dividing the model into three parts: water stream, splashing spray, and spray cloud. Among them, the behavior of spray cloud has much effects on the waterfall appearance as well as the water stream. Therefore, we have simulated the behavior of a waterfall including spray cloud in different environments, and found that the environment in front of the waterfall affects the spray cloud behavior.

The Change in Spectrum of Drops in the Exploitation Process of Agricultural Nozzles

Abstract Agricultural nozzles usually produce a different drops size depending on the pressure and the physical condition (work life) of the nozzle besides producing a wide range of the drops spectrum in the spray cloud. In this paper the standard flat fan nozzles were investigated regarding the effect of the working pressure and the nozzle physical condition (new and worn nozzles). The size of drops and the spectrum of drops across the long axis of the spray pattern were examined by using Sympatec GmbH Laser Diffraction. Reducing the working pressure from 3 to 2 and then to 1 caused production of larger drops, also using worn nozzles (especially with lower pressure) changed the drops size which is expected to be produced from the new nozzles. The standard flat fan nozzles produced a wide range of the drops spectrum inside the spray cloud, generally small drops (less than 150 µm) concentrated in the middle of the spray pattern while the big drops (250-350µm) were situated on the edge positions (70 cm from the centerline) of the spray pattern.

Initial Laboratory Measurements of the Evaporation Rate of Droplets inside a Spray Cloud

This article calculates the evaporation rate of water droplets stacked on several threads, positioned downwind of one another. The measurement approach was used previously to determine the evaporation rate of isolated suspended droplets, on a single thread, for development of the Spray Drift Task Force (SDTF) droplet evaporation data base. Here, the effect of evaporating droplets upwind of other droplets is examined, recovering the effective evaporation rate of individual water droplets surrounded by other water droplets in a spray cloud. The results quantify the modified wet bulb temperature depression felt by the droplets within the cloud and are used to compare AGDISP model predictions with SDTF aerial deposition data.

Droplet trajectories of wave-impact sea spray on a marine vessel

Marine icing phenomena are strongly dependent on the rate of water impact to marine vessels. The most important source of this incoming water is wave-impact sea spray. There is limited understanding of droplet size and velocity distributions of wave-impact sea spray. Initial distributions of the size and velocity of droplets are crucial for the calculation of the droplet path and consequently for determining the water impact to every individual place on marine vessels. This paper develops a new model of wave-impact sea spray using a distribution of the size and velocity of droplets at the edge of the vessel. The concepts of water-sheet breakup and droplet breakup lead to an inverse dependence between the size and velocity of droplets after the breakup process. Droplets take different paths and form a spray cloud in front of the vessel. The liquid water content in front of the vessel can be calculated by considering the arrangement, sizes, and velocities of a set of droplets in the spray cloud. The response of the droplet trajectory model to various initial conditions with different sets of droplet sizes and velocities is examined. The numerical results are compared to real data from field observations. Droplet sizes are inversely proportional to droplet velocities, as verified by liquid water content data obtained by the field observations. This paper proposes the use of this inverse relationship based on physics of the breakup process as the initial data for calculating the wave-impact sea spray trajectory in front of a vessel.

Modeling of spray jet flame under MILD condition with non-adiabatic FGM and a new conditional droplet injection model

This paper reports a numerical study on the Delft Spray-in-Hot-Coflow (DSHC) flame with a new OpenFOAM solver developed by the authors, in which the Flamelet Generated Manifolds (FGM) model has been implemented, and used to account for the Turbulence-Chemistry Interaction (TCI). The enthalpy loss effect due to droplet vaporization is considered by employing an additional controlling parameter in the FGM library. Different configurations for generating three dimensional non-adiabatic FGM library are tested. Analysis of the DSHC experimental data suggested that flash boiling influences the atomization of liquid fuel in the DSHC burner. This introduces new challenges for specifying precise spray boundary conditions. A conditional injection model is proposed to provide precise spray information at the injector exit plane (Z=0mm). In this conditional injection model, the droplets have an asymmetric distribution around the spray half angle, in agreement with experimental observations. Also, the possible range of droplet injection angle is conditioned upon the droplet size (mass). Droplet initial velocity magnitude is scaled such that it peaks at the spray half angle direction and reaches a minimum at the edge of the spray cloud. The results obtained show that this model significantly improves the prediction of all the properties examined compared to standard injection model. Comparison between Unsteady Reynolds Averaged Navier Stokes (URANS) and Large Eddy Simulation (LES) is made, and it is found that the LES predicted similar gas phase velocity and better temperature profiles compared to experimental data than URANS, mainly due to the better performance of the dynamic model for mixture fraction variance used in LES. The improvement of the temperature prediction by the non-adiabatic FGM was clearly demonstrated by comparing the results obtained with an adiabatic FGM table. Strong droplet–flame interaction was shown to exist in the DSHC flame. Large droplets have ballistic trajectories at the early stage of their lifetime, and can penetrate the flame and survive until far downstream outside the main reaction region. Movement of these large droplets strongly deform the shape of the flame. Rapid evaporation of droplets in the reaction region may also cause local quenching. Small droplets are quickly convected towards the central region and vanish soon, forming a fuel rich and high temperature condition in the center. These phenomena have been captured with the LES/non-adiabatic FGM modeling approach developed in this paper.

Observation and modeling research of high-velocity flushing effect on the performance of BEAM

Blasting erosion arc machining (BEAM) is a novel high efficiency electrical erosion process, which is characterized by a powerful multi-hole inner flushing. In order to study the influence of the high-velocity flushing on the performance of BEAM, a single discharge experiment is carried out on a specially designed observation apparatus, and the phenomena that occurred during the discharge is observed using a high-speed video camera. During the discharge process, a spray cloud of the removed debris near the downstream side of the discharging point is captured by the camera. Tail shaped crater and erosion-corrosion features are also found on the workpiece and electrode surfaces, respectively. These observed phenomena imply that the high-velocity flushing can greatly improve the melting metal removal from the molten pool thereby improving the material removal rate (MRR). For purpose of exploring the mechanism behind, the flow field and pressure distribution of the high-velocity flushing are analyzed by using computational fluid dynamic (CFD) method. The analyzed results indicate that a low-pressure suction effect exists on the downstream side of the electrodes. With the help of the low-pressure suction effect, the high-velocity flushing can continuously take the molten metal out of the molten pool during the discharge, resulting in the reduction of the overheating of the molten metal and improve the efficiency of the discharging energy. Thereby, the work in this paper helps to explain why the high-velocity flushing can markedly promote the material removal rate.