Droplet Trajectories Research Articles

Turbulence-induced droplet grouping and augmented rain formation in cumulus clouds

This paper provides the first observational analysis of how droplet separation is impacted by the flinging action of microscale vortices in turbulent clouds over a select radii range and how they vary over cloud cores and along the peripheral edges. It is premised that this mechanism initiates droplet separation within a cloud volume soon after condensational growth, largely in the cloud core, and operates until the cloud droplet radii exceed 20–30 µm when this effect fades rapidly. New observations are presented showing how microscale vortices also impact the settling rates of droplets over a critical size range (6–18 µm) causing them to sediment faster than in still air affecting swept volumes and thereby impacting the rain initiation and formation. Large-scale atmospheric models ignore these microscale effects linked to rapid droplet growth during the early stages of cloud conversion. Previous studies on droplet spatial organization along the cloud edges and inside the deep core have shown that homogeneous Poisson statistics, indicative of the presence of a vigorous in-cloud mixing process at small scales obtained, in contrast to an inhomogeneous distribution along the edges. In this paper, it is established that this marked core region, homogeneity can be linked to microscale vortical activity which flings cloud droplets in the range of 6–18 µm outward. The typical radius of the droplet trajectories or the droplet flung radii around the vortices correlates with the interparticle distance strongly. The correlation starts to diminish as one proceeds from the central core to the cloud fringes because of the added entrainment of cloud-free air. These first results imply that droplet growth in the core is first augmented with this small-scale interaction prior to other more large-scale processes involving entrainment mixing. This first study, combining these amplified velocities are included in a Weather Research and Forecasting- LES case study. Not only are significant differences observed in the cloud morphology when compared to a baseline case, but the ‘enhanced’ case also shows early commencement of rainfall along with intense precipitation activity compared to the ‘standard’ baseline case. It is also shown that the modelled equilibrium raindrop spectrum agrees better with observations when the enhanced droplet sedimentation rates mediated by microscale vortices are included in the calculations compared to the case where only still-air terminal velocities are used.

Research on icing scaling technology for large civil aircraft icing wind tunnel test

This article explores the icing scaling technology for large civil aircraft icing wind tunnel tests. Based on the typical critical icing conditions of large civil aircraft and the calibration of icing wind tunnel, and through the similarity analysis of water droplet trajectories, water collection, and energy balance, four similar parameters, namely modified inertia parameter, drop energy transfer parameter, stagnation freezing coefficient, and accumulation parameter, were selected as similarity criteria for icing scaling. Based on this criteria, icing scaling was conducted on the critical icing conditions of large civil aircraft, and the scaling results were evaluated by icing code. The results show that the water droplet collection and the ice shape before and after the scaling are in good agreement, and the similarity criteria used are appropriate. Finally, icing wind tunnel test was conducted in 3m × 2m test section using scaled icing conditions. The test results show that the main characteristics of the experimental ice shape are in good agreement with the calculated ice shape, and the calculated ice shape is more critical. The calculated ice shape can be used as a critical ice for aerodynamic wind tunnel tests and flight tests with simulated ice.

Investigating the impact of air distribution on spray dryer operability using CFD simulations and pilot-scale experiments

Fouling reduces spray dryer operability. The impact of different configurations of a spray dryer on operability and nozzle-zone agglomeration stimulated by dry powder dosing was investigated through a combination of CFD simulations and pilot-scale experiments. Included were two positions of the nozzle and dry powder introduction, and two degrees of air swirl. Air flows and droplet trajectories were simulated and a particle collision model was built in. The experiments were executed using a single stage co-current spray dryer with concentrical fines return. A high nozzle position (6 cm below the air inlet) resulted in undesired fouling due to an upward air flow causing wet droplets to collide with the roof. The operability was improved by lowering the nozzle position 25 cm as there was less fouling. With a low nozzle position, the degree of air swirl only had a limited effect on fouling. Surprisingly, agglomeration did not seem to be significantly affected by air distribution in both the simulations and the experiments. This means that there is some freedom in the design of a spray dryer in terms of agglomeration. Overall, the findings highlight the importance of well-designed spray drying operations to reduce fouling and thus minimize product waste.

Research on the Impact of Gas Flow Rate on Multiphase Flow Micro-jet Conformal Printing

This study aims to explore the role of gas flow rate in multiphase flow micro-jet conformal printing and investigate its influence on the characteristic line width and morphology of printed conductive lines. A research methodology combining numerical simulation and experimental validation is employed. By simulating the movement trajectory of atomized droplets inside the micro-jet printhead during the multiphase flow micro-jet conformal printing process, the impact of focus ratio on the printing process and the printed conductive lines is studied using a controlled variable approach. Corresponding experiments are designed to validate the effects. The simulation and experimental results demonstrate that the characteristic line width of printed conductive lines gradually decreases as the focus ratio increases. At a focus ratio of 2.5, the characteristic line width of printed conductive lines can reach 93μm, without noticeable defects such as satellite droplets, deposition voids, or overspray. Gas flow rate significantly influences the characteristic line width and morphology of printed conduct conformal printing process. The consistency between simulation data and experimental results validates the feasibility of multiphase flow micro-jet conformal printing simulation, laying a foundation for further research in this field.

Self-propulsion of a droplet induced by combined diffusiophoresis and Marangoni effects.

Chemically active droplets display complex self-propulsion behavior in homogeneous surfactant solutions, often influenced by the interplay between diffusiophoresis and Marangoni effects. Previous studies have primarily considered these effects separately or assumed axisymmetric motion. To understand the full hydrodynamics, we investigate the motion of a two-dimensional active droplet under their combined influences using weakly nonlinear analysis and numerical simulations. The impact of two key factors, the Péclet number ( ) and the mobility ratio between diffusiophoretic and Marangoni effects ( ), on droplet motion is explored. We establish a phase diagram in the space, categorizing the boundaries between four types of droplet states: stationary, steady motion, periodic/quasi-periodic motion, and chaotic motion. We find that the mobility ratio does not affect the critical for the onset of self-propulsion, but it significantly influences the stability of high-wavenumber modes as well as the droplet's velocity and trajectory. Scaling analysis reveals that in the high regime, the Marangoni and diffusiophoresis effects lead to distinct velocity scaling laws: and , respectively. When these effects are combined, the velocity scaling depends on the sign of the mobility ratio. In cases with a positive mobility ratio, the Marangoni effect dominates the scaling, whereas the negative diffusiophoretic effect leads to an increased thickness of the concentration boundary layer and a flattened scaling of the dropletvelocity.

Fuel effects on the electrostatic control of charged droplet trajectories

The use of electrostatic fields to control the trajectory of charged droplets is investigated as a new technology to enhance mixing in liquid-fuelled combustors. The canonical configuration of a spray in crossflow is numerically studied with a focus on the effects of the fuel type on the onset of charge-induced breakup and droplet trajectories for a range of bulk flow velocities and electrostatic field strengths at conditions relevant to gas turbine applications. The investigated fuels are ethanol, n-heptane, and n-decane. Operational maps for each fuel are provided to assist the selection of the external electrostatic field required to achieve a balance between the drag and electrostatic forces, and enable a system design that considers fuel flexibility. The results demonstrate that the fuel type has an important impact on the diameter at which the charge-induced breakup is achieved, which mainly depends on the droplet equilibrium temperature. It is also shown that, for cases where the droplet net charge is fixed to a given fraction of the maximum possible charge (based on the Rayleigh limit), the temperature of the droplet at injection could be used as a parameter to control the onset of secondary breakup. Analysis of the strength of the electrostatic field necessary to achieve droplet stabilisation in a bulk flow shows that a balance between the electrostatic and drag forces can only be achieved for relatively low values of the bulk flow velocity, if the strength of the electrostatic field is kept below the breakdown limit of the carrier phase. This balance mainly depends on the droplet net charge and flow conditions, whereas the effect of the type of fuel on the drag force is less important. When the charge is imposed as a fraction of the maximum possible value at injection, for low values of the bulk flow velocity, the strength of the electrostatic field that balances the drag tends to become independent of the droplet diameter for a wide range of droplet sizes. Further investigation of the trajectories of evaporating droplets demonstrates that, although affected by the type of fuel through the evaporation rate, with the same settings of the electrostatic field, it is possible to achieve evaporation in a confined region for all the fuels and ambient conditions studied in this work once the initial droplet charge and initial droplet diameter are fixed. The present findings offer new insights for the development of future technologies for fuel preparation with enhanced mixing and fuel flexibility.

Experimental study on the effects of pressure loss on uniformity, application rate and velocity on different working conditions using the dynamic fluidic sprinkler

An experiment was conducted to determine the effects of pressure loss, combined spacing, and.coefficients of uniformity on the dynamic fluidic sprinkler. Spline interpolation was used to convert the radial water volume into grid-type data and various pressure conditions were used to simulate the three-dimensional water distribution under square and triangular combinations of sprinklers. For each of the combinations of the sprinklers, experiments were performed at operating pressures of 0.15, 0.2, 0.25, and 0.3 MPa, respectively. To find the optimum spatial distribution of sprinklers, three different sprinkler intervals, 1R, 1.2R, and 1.4R, were performed for the square and triangular combinations. The droplet size distributions were also measured along a radial transect from the sprinkler for each operational pressure using the Thies Clima Laser Precipitation Monitor. The results demonstrated that the average values of the inclination angles of the water droplet trajectory curves were 60.78° and 68.85° as the pressure rose from 0.15 MPa to 0.3 MPa. When the pressure exceeds 0.2 MPa, the square combination's distribution uniformity coefficients of 25% low and high values were higher than those of the triangle combination. Triangular combination coefficients of uniformity (CU) values initially decreased and then increased as sprinkler spacing increased, with the CU value under 1.4R spacing reaching 73.85%. At a 1.2R interval, the CU value of a triangular combination was 8.49% lower than that of a square combination, which is a significant difference. Peak irrigation values for the square combination, when the pressure was changed from 0.1 to 0.3 MPa, were 29.97, 22.9, 19.8, 19.91, and 19.21 mm h−1, respectively. The CU values at 0.2, 0.25, and 0.3 MPa decreased at rates of 0.07%, 1.36%, and 0.8%, respectively, when the pressure was reduced by 10%.

Research on the Methods for Obtaining Droplet Impingement Characteristics in the Lagrangian Framework

The impact of supercooled water droplets is the cause of aircraft icing, and the acquisition of impingement characteristics is the key to icing prediction and the design of ice protection systems. The introduction of water droplet collection efficiency is required to obtain the characteristics for the Lagrangian method. In this work, a traditional flow tube method, a local flow tube method, and a statistical method are established to calculate the local collection efficiency, based on Lagrangian droplet trajectories. Through the numerical simulations of the air–droplet flow field around an NACA 0012 airfoil, the accuracies of the three methods in regard to collection efficiency are verified. Then, these three methods are applied to obtain the results for water droplet trajectories and the collection efficiency of an S-shaped duct, a 2D engine cone section and an icing wind tunnel. The results show that the distributions of water droplet collection efficiency obtained by the three methods are consistent and the three methods are all feasible when the water droplets do not overlap or cross before hitting the aircraft surfaces. When the water droplets are shadowed by upstream surfaces or blown by air injection, the droplet trajectories might overlap or even cross, and the local collection efficiencies obtained by the traditional flow tube method, local flow tube method, and statistical method might differ. The statistical method is relatively accurate. However, not all the droplet impingement characteristics obtained by the three methods are different due to these effects, and the non-crossing of the droplet trajectories is not a necessary condition for the use of the flow tube method. The effects of trajectory crossings are analyzed and discussed in detail in different situations for the three methods. This work is helpful for understanding and accurately calculating the droplet impingement characteristics and is of great significance for simulations of the aircraft icing process and anti/de-icing range.

Numerical simulation of the transport of breath-exhaled aerosol from manikin with realistic nasal airway over short social distances

This study delves into the dynamics of respiratory droplet dispersion in indoor settings, focusing on three pivotal aspects: the use of Respiratory Models (RM) versus Non-Respiratory Models (NRM), the influence of social distancing, and the size of exhaled droplets. Our advanced simulations reveal that RMs are essential for accurately predicting airflow and droplet trajectories, whereas NRMs tend to overestimate deposition. We further explore how variations in the distance between an infector and a susceptible individual significantly affect droplet behavior and potential transmission. Additionally, our findings highlight the critical role of droplet size in determining their travel and deposition patterns. These insights collectively provide a comprehensive understanding of aerosol transmission in indoor environments, offering valuable contributions to public health strategies aimed at controlling airborne diseases.

Droplet deposition of agrochemical spraying: Comparison of results from a random‐walk model and CFD simulations

AbstractThe effectiveness of agricultural spraying processes depends considerably on the ability of the atomized droplets to reach the target site in the desired amount. In this work, two mathematical models to study the trajectories and deposition of atomized droplets are implemented and compared. On the one hand, a computational fluid dynamics (CFD) coupled with discrete phase model (DPM) is implemented to calculate the trajectories of atomized droplets and determine distances at which the droplets are deposited. The continuous phase (atmospheric air) is modelled by continuity, momentum, and energy equations. On the other hand, a Lagrangian random‐walk (LRW) model based on force and energy balances to predict the pulverization process of a nozzle is formulated and implemented in Python. Both models take into account the effects of drag, gravity, buoyancy, and evaporation on individual droplets, as well as the impact of atmospheric stability and dispersion. By tracking a large number of trajectories, meaningful estimates of dispersal statistics can be obtained. The LRW model accurately replicated the trajectories, deposition distances, and final diameters of atomized droplets for three atmospheric stability cases, compared with CFD simulation results. The results of both models agreed that 100 μm droplets were most susceptible to wind‐induced spray drift, depositing at the furthest distances from the nozzle. In addition, 50 μm droplets exhibited a significant tendency to evaporate entirely before reaching the ground. The LRW model is found to be a cost‐effective alternative for estimating spray drift compared to the computationally intensive CFD approach.

Computation of aluminum droplet ejection and flight in microgravity

Persistent and frequent space explorations are limited by real-time parts supply and it is significant to achieve space manufacture, such as the droplet-based printing. In order to study the microgravity environment effect on droplet-based printing, this paper proposed an effective method to research the effect of space station environmental g-jitter (according to NASA experimental signal) on droplet ejection and flight process. The heat transfer, transient gravity acceleration and Marangoni effect are studied based on the improved model. The results show that the g-jitter is in the order of 10−3 magnitude and the effect on aluminum droplet ejection could be ignored when nozzle diameter (dn) is smaller than 0.1 mm and so do ground case. Combined with the ground microgravity simulation of SnPb alloy lateral ejection experiments, it can be obtained that the ejected single droplet is characterized by capillary number (Ca≤0.002), the droplet flight trajectory is dependent on the Froude number (Fr) and the laminar-turbulence transition exists during the droplet flight process. The relationship formulation between the deviation along gravity direction and the deposition distance is introduced to control and adjust the droplet flight trajectory. Moreover, the temperature effect on material property, such as surface tension and so on, has effect on the droplet breakup length. The g-jitter field enhances the Marangoni effect resulting in the deviation of droplet trajectory. In microgravity field, the computational droplet oscillation period is well coincidence with theoretical equation. Improved KIC-SST based model is available for simulating droplet-based printing in microgravity.

Численное исследование полидисперсных двухфазных течений в осесимметричном сопле Лаваля с учетом силы Магнуса, действующей на вращающиеся капли

The available papers on two-phase flows in de Laval nozzles are focused on the effect of various initial conditions, models of coagulation, fragmentation, and rotation of droplets on their local and integral characteristics. Some papers note that due to the difference in the velocities of the gas and droplets along the nozzle axis, the Magnus force acts on the rotating droplets perpendicular to the specified difference and deflects the trajectories of the droplets toward the nozzle wall. In an earlier paper, the authors proposed a mathematical model of a two-phase flow in an axisymmetric de Laval nozzle that accounts for the Magnus force on the basis of the kinetic equation. The present article is devoted to a numerical study of a polydisperse two-phase flow in a de Laval nozzle with account for the coagulation, fragmentation, and rotation of droplets and the Magnus force. This study is based on the “monodisperse” model of fragments developed by I.M. Vasenin and A.A. Shreiber, the method of labeled drops (the Lagrange method), and the finite-difference schemes of second order accuracy. The calculations are carried out for a test nozzle configuration with condensate formation on the nozzle wall both with and without the Magnus force accounted. The calculated results show that the Magnus force has different impacts on the trajectories of droplets of various sizes. It should be noted that the limiting trajectories of the droplets approach the nozzle wall due to the Magnus force, resulting in the earlier dropout on the wall. Therefore, when designing the divergent section of the nozzle, it is necessary to consider the revealed approach of the location of the dropout, which is associated with the Magnus force, to the nozzle throat.

Multi-scale analysis of respiratory droplets transport within the breathing cloud

Infectious diseases are transmitted primarily through pathogen laden droplets commonly exhaled during respiratory events such as breathing, coughing, or sneezing. The transport and evaporation of droplets are governed by the fundamental laws of fluid mechanics and convection-diffusion. From these, analytical models can be created helping in better understanding pathogens transmission from a mechanical perspective. The droplet transport within the humid air breath cloud and the local ventilation are crucial for accurately predicting the droplet fate. Different levels of complexity are possible for modelling the breath cloud, from simple 1D models to complex unsteady 3D simulations including discrete phase models for the droplets simulation. The former are too simple to capture the fluid dynamics of intermittent jets in detail, while the latter are too computationally expensive. The current work presents a novel multi-scale approach where an analytical model of the droplet transport and evaporation is coupled to unsteady CFD simulations of warm humid puffs of exhaled air. The proposed model has the advantage of the accuracy of an analytical model and the computational cost of a relatively standard unsteady CFD simulation, and can be used to predict the trajectory of the exhaled droplets for a variety of respiratory events.

Visualisation of Droplet Flow Induced by Ultrasonic Dental Cleaning

IntroductionDuring dental treatment procedures ultrasonic scalers generate droplets containing microorganisms such as bacteria and viruses. Hence, it is necessary to study the dynamic properties of generated droplets in order to investigate the risks associated with the spread of infection. The aim of this study was to visualise the flow state of droplets and to evaluate the impact of droplets generated during the use of an ultrasonic scaler during an oral surgical procedure. MethodsWe studied the spatial flow of liquid droplets through a combination of imaging and numeric simulation of a simulated dental treatment processes. First, we photographed the real time images of the ultrasonic scaler and evaluated the images using image-processing software Image J to visualise the flow of liquid droplets. Finally we simulated the flow process of liquid droplets by using the initial velocity of droplet splashing and the angle of the obtained information using computerised fluid dynamics technology. ResultsUnder different working conditions, the droplet particle splashing velocity, maximum height, and spray angle varied, but the particle trajectory was generally parabolic. The maximum droplet velocity varied between 3.56 and 8.56 m/s, and the splashing height was between 40 and 110 mm. ConclusionsDuring risk assessment of an ultrasonic scaler usage, difficulties arise due to the insufficient research on droplet velocity and distribution. This study aims to address this gap by visualising the flow trajectories of droplets generated by ultrasonic scalers. The obtained data will assist in developing more effective interventions based on spatial and temporal distribution of droplets. This provides a new approach for droplet particle research and offers new strategies for public health prevention and control.

A novel concept for a rib turbulator for optimizing the cooling performance in a square channel

In gas turbine operations, realizing the appropriate cooling of blades and vanes is crucial for ensuring long-term durability and high thermal efficiency. Internal convective cooling is widely used to direct coolant through a channel comprising rib turbulators to enhance the effectiveness of the cooling process. In this study, a numerical simulation is conducted to evaluate the effects of novel rib turbulator configurations under mist/steam two-phase conditions, specifically in relation to secondary flow and heat transfer characteristics. The morphologies of the secondary flow distribution and mist droplet trajectories induced by different rib turbulator configurations are carefully evaluated to elucidate the underlying mechanism of the heat transfer enhancement. Thus, the findings indicate that the configuration of the rib turbulator significantly affects the secondary flow distribution. In the novel concepts of discrete v-shaped rib turbulators with a single break and those with a double break, a notable increase in the longitudinal secondary flow was observed with a higher turbulence intensity. Moreover, such secondary flow compels mist droplets to accumulate and assemble at various locations within the channel. Subsequently, the heat transfer enhancement was localized in areas where the mist droplets accumulated in significant quantities. In terms of the optimization of the rib turbulator configuration, the adoption of a v-shape with a single break and discrete channel resulted in an enhancement of the Nusselt number by 45.07 % and the thermal performance factor by 88.57 %.

Coalescence-Induced Droplet Jumping for Electro-Thermal Sensing.

Jumping droplet condensation, whereby microdroplets (ca. 1-100 μm) coalescing on suitably designed superhydrophobic surfaces jump away from the surface, has recently been shown to have a 10× heat transfer enhancement compared to filmwise condensing surfaces. However, accurate measurements of the condensation heat flux remain a challenge due to the need for low supersaturations (<1.1) to avoid flooding. The low corresponding heat fluxes (<5 W/cm2) can result in temperature noise that exceeds the resolution of the measurement devices. Furthermore, difficulties in electro-thermal measurements such as droplet and surface electrostatic charge arise in applications where direct access to the condensing surface, such as in isolated chambers and small integrated devices, is not possible. Here, we present an optical technique that can determine the experimental electro-thermal parameters of the jumping droplet condensation process with high fidelity through the analysis of jumping droplet trajectories. To measure the heat flux, we observed the experimental trajectories of condensate droplets on superhydrophobic nanostructures and simultaneously matched them in space and time with simulated trajectories using the droplet dynamic equations of motion. Two independent approaches yielded mean heat fluxes of approximately 0.13 W/cm2 with standard deviations ranging from 0.047 to 0.095 W/cm2, a 79% reduction in error when compared with classical energy balance-based heat flux measurements. In addition, we analyzed the trajectories of electrostatically interacting droplets during flight and fitted the simulated and experimental results to achieve spatial and temporal agreement. The effect of image charges on a jumping droplet as it approaches the surface was analyzed, and the observed acceleration has been numerically quantified. Our work presents a sensing methodology of electro-thermal parameters governing jumping droplet condensation.

A statistical analysis of exhaled respiratory droplet trajectory distribution in view of assessing the risk of infectious disease transmission

In the present work an analytical model of exhaled droplet trajectory and evaporation is employed to perform a preliminary statistical analysis of the droplet spatial distribution. The analysis is carried out for a set of over twenty thousand droplets distributed in the range of diameters from 0.1 μm to 1 mm. The type of respiratory events modelled are mouth breathing and speaking. The analytical model employed has been recently developed by the authors. It implements the fundamental laws of fluid dynamics and convection-diffusion, and features a 2D empirical numerical model of buoyant intermittent jet modelling the exhaled breath cloud. A discrete random walk turbulent dispersion model is also included allowing statistical analysis of the droplet trajectory to be performed. With proper boundary conditions any type of respiratory event can be simulated making the model particularly versatile. From the analysis, spatial virus concentration maps are derived for the largest droplets falling to the ground, and for the smaller droplets remaining airborne in the area in front of an infected emitter and successively uniformly dispersed in the ambient. This allows to estimate the risk of infection by fomite, direct inhalation and indirect inhalation routes, and provide a better understanding of infectious disease transmission risks.

Retracted: Safe Distance of Virus Quantitative Analysis and Simulation of the Trajectory of Pathogen-Containing Droplets in the Air Respiratory Airways

Retracted: Safe Distance of Virus Quantitative Analysis and Simulation of the Trajectory of Pathogen-Containing Droplets in the Air Respiratory Airways

Migration Movements of Accidentally Spilled Oil in Environmental Waters: A Review

Accidentally spilled oil can cause great harm to the ecological balance of water once it enters the environmental waters. Clarifying its movement behavior and migration law in water has been the focus of environmental hydraulics research. This review starts from the mechanism of the oil spill migration process, and firstly reviews the kinematic characteristics of the smallest moving unit of the oil spill, the individual oil droplet, as well as focusing on several key aspects such as droplet shape, trajectory, terminal velocity and drag coefficient. Subsequently, considering the commonalities and differences between inland riverine and oceanic environments, different aspects of oil droplet collision, coalescence, breakage, particle size distribution, and vertical diffusion are discussed separately. Finally, the current status of research on the migration laws of accidental oil spills in environmental waters is summarized, and feasible future research directions are proposed to address the emerging research problems and research gaps.

Droplet Transportation on Liquid-Infused Asymmetrically Structured Surfaces by Mechanical Oscillation and Viscosity Control.

The transportation of droplets on solid surfaces has received significant attention owing to its importance in biochemical analysis and microfluidics. In this study, we propose a novel strategy for controlling droplet motion by combining an asymmetric structure and infused lubricating oil on a vibrating substrate. The transportation of droplets with volumes ranging from 10 to 90 μL was realized, and the movement speed could be adjusted from 1.45 to 10.87 mm/s. Typical droplet manipulations, including droplet transportation along a long trajectory and selective movement of multiple droplets, were successfully demonstrated. Through experimental exploration and theoretical analysis, we showed that the adjustment of droplet transport velocity involves an intricate interaction among the Ohnesorge number, droplet volume, and input amplitude. It can potentially be used for the more complex manipulation of liquid droplets in microfluidic and biochemical analysis systems.