Suspended Droplets Research Articles

Suspended Droplets Discharge Characteristics

ABSTRACTThis study investigates discharge phenomena in suspended droplets using needle–needle electrodes. By employing ultrasonic suspension technology for noncontact droplet suspension and high‐speed cameras for capturing time‐resolved discharge images, the study examines the impact of droplets on discharge characteristics and morphology. Results show that droplets alter the electric field distribution, affecting discharge paths. Low‐conductivity droplets hinder discharge, causing deflection or changes in the discharge channel, whereas high‐conductivity droplets act as suspended electrodes, facilitating discharge channel formation, reducing breakdown voltage and shortening the establishment time. Droplets transition from ellipsoid to flat and back during discharge, with high‐conductivity droplets potentially undergoing liquid explosion. These findings are crucial for designing high‐voltage equipment in liquid‐contaminated environments.

Comparative experiments on the flow morphology of liquid nitrogen and water in perforated structured packing

Cryogenic distillation is the primary method for air separation, with corrugated plate packing as the main packing for heat and mass transfer between nitrogen and oxygen. The perforated structure on the corrugated plate packing can directly change the liquid distribution characteristics, thereby affecting the packing’s flow and mass transfer performance. Currently, the effect of perforated structure is mainly revealed by room temperature fluids such as water and air, while on the practical cryogenic fluids such as liquid nitrogen, it is seldom studied. In this study, the effects of perforation size ranging from 2 to 8 mm on the flow of water and liquid nitrogen on the perforated plates were investigated and compared by a high-speed camera. It was observed that water could hardly flow through the perforations, it completely covers the perforations, forming a continuous liquid film on the surface of the perforations. The expected role of perforations in redistributing water on the back side of the corrugated plate is relatively minor. While for liquid nitrogen, the presence of the perforated structure helps fluid redistribution on the back side of the plate, as it can easily flow through the perforations with diameters between 2 mm and 8 mm. It is found that when the perforation diameter exceeds 6 mm, liquid nitrogen will form suspended liquid droplets within the holes, which could be a risk of premature flooding. Under similar conditions, the wetting rate of liquid nitrogen reaches 86.90 % −99.48 %, higher than that of water which is about 10.26 % −78.82 %. The results show that perforations have quite different effects on the flow characters of water and liquid nitrogen due to their disparate physic properties.

Ejection and deposition of mica suspension droplets under electric field

Inkjet printing of ceramic materials is a shaping process of interest for building micrometer-sized components. It consists of depositing droplets of colloidal inks according to a printing pattern designed to obtain a given final part. Improving the printed part properties, e.g., thermal or electrical, requires to tailor the printed material's local structure and orientation. Electric field is an efficient external stimulus to control particle orientation. A major challenge is to efficiently couple the effects of electric field and those of capillary, viscous, and evaporation phenomena occurring during inkjet printing. In this paper, the effect of an external electric field on the structuration of inkjet deposits is investigated. Suspensions of mica platelets dispersed in binary mixtures of chloroform and silicone oil are ejected on demand on a glass plate. An electric potential difference is applied by means of a set of electrodes below the glass substrate, separated by a small gap in order to maximize the electric field on the surface of the plate. A cartography of splat morphology and structuration for different inks as a function of applied field is performed. Promising experimental conditions display particle arrangement and limited splat deformation, whereas others lead to fingering. This paves the way to a novel additive shaping process by adding another smaller scale of structuration to inkjet printed parts.

Alginate/organo-selenium composite hydrogel beads: Dye adsorption and bacterial deactivation

Post-COVID-19, the risk and spread of germs, coupled with wastewater contamination, have become critical concerns. Wastewater contains waterborne bacteria and various contaminants like dye molecules, threatening water safety. Traditional adsorption methods address pollutant removal or pathogen inactivation separately, but a dual-action solution is increasingly essential. This study presents alginate/selenium composite hydrogel beads with the potential to simultaneously remove dyes and deactivating bacteria. Fabricated by dropping suspension droplets into a calcium ion bath, these beads were tested for dye adsorption and antibacterial efficacy. Beads with 50 wt% organo‑selenium demonstrated the highest methylene blue (MB) adsorption capacity and nearly 100 % deactivation efficiency against Pseudomonas aeruginosa, while those with 20 wt% showed no significant improvement. Mechanistic studies reveal that organo‑selenium induces stacking effects and reduces surface charges, enhancing MB adsorption and antibacterial performance. The alginate/organo‑selenium composite hydrogel beads offer a potential effective and sustainable solution for tackling the complex issue of wastewater pollutants.

Molecular-level studies of extracellular matrix proteins conducted using atomic force microscopy.

Extracellular matrix (ECM) proteins provide anchorage and structural strength to cells and tissues in the body and, thus, are fundamental molecular components for processes of cell proliferation, growth, and function. Atomic force microscopy (AFM) has increasingly become a valuable approach for studying biological molecules such as ECM proteins at the level of individual molecules. Operational modes of AFM can be used to acquire the measurements of the physical, electronic, and mechanical properties of samples, as well as for viewing the intricate details of the surface chemistry of samples. Investigations of the morphology and properties of biomolecules at the nanoscale can be useful for understanding the interactions between ECM proteins and biological molecules such as cells, DNA, and other proteins. Methods for preparing protein samples for AFM studies require only basic steps, such as the immersion of a substrate in a dilute solution or protein, or the deposition of liquid droplets of protein suspensions on a flat, clean surface. Protocols of nanolithography have been used to define the arrangement of proteins for AFM studies. Using AFM, mechanical and force measurements with tips that are coated with ECM proteins can be captured in ambient or aqueous environments. In this review, representative examples of AFM studies are described for molecular-level investigations of the structure, surface assembly, protein-cell interactions, and mechanical properties of ECM proteins (collagen, elastin, fibronectin, and laminin). Methods used for sample preparation as well as characterization with modes of AFM will be discussed.

A low-Mach volume-of-fluid model for the evaporation of suspended droplets in buoyancy-driven flows

This study introduces a comprehensive numerical model capable of simulating the evaporation of suspended droplets under different gravity conditions. Unlike previous studies, this work provides a detailed description of the multicomponent evaporation process by integrating: (i) interface-resolved evaporation; (ii) suspension by the action of the surface tension force, and (iii) variable physical properties. The model effectively captures complex phenomena such as thermal expansion, natural convective fluxes, and liquid internal recirculation, which cannot be directly resolved using more widespread spherically-symmetric models. Validation against experimental data confirms the model’s accuracy in predicting the droplet evaporation dynamics, and its utility in resolving discrepancies between prior numerical simulations results and experimental data. The model was implemented in the Basilisk framework; both the code and the simulations setups are freely available on the Basilisk sandbox.

A polynomial temperature profile model for suspended droplet evaporation over a wide range of ambient pressures and convection conditions

The suspended droplet technique has been widely applied in experimental droplet evaporation studies, but heat conduction caused by support fiber can change the evaporation characteristics. In the present study, a novel theoretical model is proposed to investigate the effect of a suspender on droplet heating and evaporation. Considering the vortex circulation inside the droplet and the heat diffusion along the support fiber, the temperature distribution is assumed to exhibit a polynomial profile. The effects of pressure on the thermodynamic and transport properties are also accounted for. The simulation results are consistent with previous experimental data over a wide range of ambient pressures and convection conditions. The performance of the new model is further compared with that of other models in terms of computational efficiency and accuracy. The new model requires an order of magnitude less CPU time than does the effective thermal conductivity model to preserve the key features of the temperature distribution accurately. In addition, a dual effect of the fiber diameter on the evaporation rate is demonstrated. With increasing fiber diameter, the evaporation rate increases and then decreases. There are two different patterns that can depict heat transfer between the suspended droplets and the fibers: an “immersed area pattern” and a “fiber temperature pattern”. A switchover in the two patterns is responsible for the dual effect, which occurs at a threshold fiber diameter related to the environment.

Generative diffusion models for synthetic trajectories of heavy and light particles in turbulence

Heavy and light particles are commonly found in many natural phenomena and industrial processes, such as suspensions of bubbles, dust, and droplets in incompressible turbulent flows. Based on a recent machine learning approach using a diffusion model that successfully generated single tracer trajectories in three-dimensional turbulence and passed most statistical benchmarks across time scales, we extend this model to include heavy and light particles. Given the particle type – tracer, light, or heavy – the model can generate synthetic, realistic trajectories with correct fat-tail distributions for acceleration, anomalous power laws, and scale dependent local slope properties. This work paves the way for future exploration of the use of diffusion models to produce high-quality synthetic datasets for different flow configurations, potentially allowing interpolation between different setups and adaptation to new conditions.

Organic suspension droplet solid-phase dispersive liquid–liquid microextraction ultra-high performance liquid chromatography tandem mass spectrometry determination of antibiotic residues in water samples

A method was developed for the simultaneous detection of 38 antibiotic residues, which included 8 sulfonamides, 14 fluoroquinolones, 9 macrolides, and 7 anthelminthics, in drinking water, tap water, and environmental water. The method involved organic suspension droplet solid-phase dispersive liquid–liquid microextraction, followed by ultra-high performance liquid chromatography tandem mass spectrometry for the analysis of the water samples. Hypersil GOLD C18 chromatography column (100 × 2.1 mm, 1.9 μm) be used for separation of target analytes that were eluted by a gradient mobile phase composition of 0.2 % formic acid–water as mobile phase A and acetonitrile as mobile phase B at a flow rate of 0.2 mL min−1. Using 0.2 mL of octanoic acid as the extractant and 0.3 mL of acetonitrile as the dispersant. Under optimal conditions, the standard curve exhibits a good linear relationship within the range of 1–50 μg L−1. The spiked recovery rate of the method ranges from 63 % to 96 %, with a relative standard deviation of 0.6 % to 7.3 % (n = 6). The detection limit of the method is between 0.1 and 0.2 μg L−1. This method is characterized by its simplicity, speed, and high sensitivity, which sets the groundwork for investigating the exposure levels and environmental behavior of antibiotics.

Spray performance simulation and experiment analysis of a greenhouse fixed-pipe twin-fluid cold fogger with different nozzle settings.

High-efficient pesticide application equipment for protected cultivation is scarce. In response, a fixed-pipe twin-fluid clod fogger (FTCF) was proposed as a potential solution. To investigate the optimal nozzle layout and spray performance, a computational fluid dynamics (CFD) model was used to study the airflow distribution and spray deposition of a FTCF with different nozzle settings using the Euler-Lagrange approach. Specifically, two piping configurations, middle-cross-inverted (MCI) and bilateral-malposed-opposite (BMO), were combined with three nozzle spacings (2 m, 3 m, 4 m) resulting in six nozzle settings. Additionally, a greenhouse spray trial was conducted to test the performance of FTCF with the selected nozzle settings and to validate the model. The simulation results revealed that MCI piping configuration exhibited a stronger airflow disturbance compared to BMO configuration, indicating a more significant air-guided effect in the MCI configuration. Combining this finding with the ground droplet distribution analysis of MCI piping configuration, it was observed that MCI-2 m had the lowest coefficient of variation (CV) for ground deposition (20.56%). Consequently, MCI-2 m was determined as the most optimal nozzle setting. Verification results demonstrated a high consistency between experimental and simulated spray deposition results. The FTCF system effectively generated a three-dimensional airflow field throughout the greenhouse environment. Furthermore, jet flow produced by FTCF disrupted the overall airflow pattern within the greenhouse space which facilitated droplet suspension and dispersion. This study provides valuable insights and innovative ideas for enhancing pesticide application technologies in protected cultivations. © 2024 Society of Chemical Industry.

Acoustic Levitation-Controlled Droplets for Contactless Enrichment and Sensitive Detection of Volatile Organic Substances Integrated with GC-MS.

Analyzing trace-level volatile organic compounds (VOCs) remains challenging due to initial sampling and preconcentration limitations. Inspired by the highly reproducible and constantly renewable electrode surface of dropping mercury electrode (DME), a contactless enrichment process was first reported by using an acoustic levitation device to trap and concentrate VOCs from gas samples onto suspended droplets, which were then directly transferred into gas chromatography-mass spectrometry (GC-MS) for real-time analysis. Compared with traditional methods injection methods, this method achieves a 46-fold increase in nicotine peak area. The detection sensitivity was enhanced significantly, attributed to the high specific surface area of the droplets and the accelerating extraction vibration. Notably, the number of identified VOCs from burning cigarettes significantly increased from 17 to 212, including 22 aromatic compounds with distinct aromas. The remarkable versatility of this method was demonstrated by effectively monitoring the dynamic changes of 16 VOCs in environmental tobacco smoke (ETS) following cigarette burning, revealing the persistence of these compounds, even after 40 min. Moreover, directly analyzing human-exhaled aerosol found that nicotine rapidly decreased while its metabolite cotinine increased, showcasing the potential for tracking human metabolism and behavior in vivo. Furthermore, multivariate data analysis of VOC profiles from six cigarette brands allowed for their visual differentiation. With versatility, sensitivity, and the ability to distinguish trace-level VOCs in realtime, this method offers promising avenues for environmental monitoring, metabolic studies, and various analytical applications.

A novel phase-field lattice Boltzmann framework for diffusion-driven multiphase evaporation

Heat transfer and phase change phenomena, particularly diffusion-driven droplet evaporation, play pivotal roles in various industrial applications and natural processes. Despite advancements in computational fluid dynamics, modeling multiphase flows with large density ratios remains challenging. In this study, we developed a robust and stable conservative Allen–Cahn-based phase-field lattice Boltzmann method to solve the flow field equations. This method is coupled with the finite difference discretization of vapor species transport equation and the energy equation. The coupling between the vapor concentration and temperature field at the interface is modeled by the well-known Clausius–Clapeyron correlation. Our approach is capable of simulations under real physical conditions and is compatible with graphics processing unit architecture, making it ideal for large-scale industrial simulations. Three validation test cases are conducted to demonstrate the consistency of the presented model, including simulations of Stefan flow, the evaporation of suspended droplets containing water, acetone, and ethanol in the air, and the evaporation of a water sessile droplet on a flat surface. The results show that the model is able to predict the behavior and characteristics of each case accurately. Notably, our numerical results exhibit a maximum relative error of approximately 1% in simulations of Stefan flow. In the case of suspended droplet evaporation, the observed maximum difference between the calculated wet bulb temperatures and those derived from psychrometric charts is approximately 0.9 K. Moreover, our analysis of the sessile droplet reveals a good agreement between the results obtained by our model for the evaporative mass flux and those obtained from the existing models in the literature for different contact angles.

Properties and combustion characteristics of bioslurry fuels from agricultural waste pyrolysis

ABSTRACT The current research investigates the combustion characteristics of bioslurry fuel derived from the products of agricultural waste pyrolysis. The bioslurry fuel was prepared by mixing biochar and pyrolysis oil. The combustion characteristics of a suspended single droplet of the bioslurry were analysed. The results indicate that an increase in pyrolysis temperature (400–600°C) lead to higher concentrations of fixed carbon (56–60%), increased ash content (16–18%), and higher calorific values (25–32 MJkg−1). As the pyrolysis temperature rises, the biochar surface becomes more porous, lower volatile matter content and particle size. As biochar content increases, the bioslurry’s density, viscosity, and caloric value increase but stability index decreases. Higher biochar content in the bioslurry increases the ignition delay and burnout time while reducing the burning rate. The bioslurry fuel contained 30% biochar achieved a calorific value of 28 MJkg−1 and a viscosity of 600 cP, comparative to conventional fossil fuels. Highlights Up to 30% BC can be added to pyrolysis oil to produce SF. Pyrolysis temperature increased FC, ash, and calorific value of biochar. Biochar surface appears more porous with increasing pyrolysis temperature. Biochar content affects bioslurry combustion characteristics.

Propagation and evaporation of contaminated droplets, emission and exposure in surgery environments revealed by laser visualization and numerical characterization

The contaminated liquid mixture containing mucosalivary fluid and blood would be aerosolized during medical procedures, resulting in higher-risk exposures. The novelty of this research is integrating laser visualization and numerical characterization to assess the propagation and evaporation of contaminated droplets, and the interactive effects of humidity and temperature on exposure risks will be numerically evaluated in surgery environments. The numerical model evidenced by experiments can predict the mass balance of ejection droplets, the minimum required fallow time (FT) between appointments, and the disinfection region of greatest concern. Around 98.4 % of the ejection droplet mass will be removed after the cessation of ultrasonic scaling, while the initial droplet size smaller than 72.6μm will dehydrate and become airborne. The FT recommendation of 30 min is not over-cautious, and the extended FT (range of 28–37 min) should be instituted for low temperature (20.5 °C) and high humidity levels (60 %RH). The variation of the temperature and humidity in the range for human thermal comfort has little influence on the area of the disinfection region (0.15m2) and the cut-off size (72.6μm) of droplet deposition and suspension. This research can provide scientific evidence for the guidelines of environmental conditions in surgery rooms.

Fabrication of heterocellular spheroids with controllable core-shell structure using inertial focusing effect for scaffold-free 3D cell culture models

Three-dimensional (3D) cell culture models capable of emulating the biological functions of natural tissues are pivotal in tissue engineering and regenerative medicine. Despite progress, the fabrication ofin vitroheterocellular models that mimic the intricate structures of natural tissues remains a significant challenge. In this study, we introduce a novel, scaffold-free approach leveraging the inertial focusing effect in rotating hanging droplets for the reliable production of heterocellular spheroids with controllable core-shell structures. Our method offers precise control over the core-shell spheroid's size and geometry by adjusting the cell suspension density and droplet morphology. We successfully applied this technique to create hair follicle organoids, integrating dermal papilla cells within the core and epidermal cells in the shell, thereby achieving markedly enhanced hair inducibility compared to mixed-structure models. Furthermore, we have developed melanoma tumor spheroids that accurately mimic the dynamic interactions between tumor and stromal cells, showing increased invasion capabilities and altered expressions of cellular adhesion molecules and proteolytic enzymes. These findings underscore the critical role of cellular spatial organization in replicating tissue functionalityin vitro. Our method represents a significant advancement towards generating heterocellular spheroids with well-defined architectures, offering broad implications for biological research and applications in tissue engineering.

Effect of coal suspension concentration and gas-air medium temperature on liquid droplets collisions

Relevance. Understanding the mechanisms of liquid droplets interaction with each other is important for many industrial and technical applications related to solving a range of problems like slag removal in a high-temperature environment, obtaining components of the desired fraction in the food industry, etc. Aim. Establishment of the main patterns of suspension droplets interaction in a gas-air environment with temperature variation. Methods. Using shadow high-speed video recording, the main patterns of the binary collision of suspensions droplets were determined. The paper introduces the results of experimental studies of the characteristics of collisions of droplets of coal-water suspensions in a gas-air environment with a temperature of 90–120°C. Parameters of the generated droplets: radius 1.0–2.2 mm, velocity 0.5–2.0 m/s. Results and conclusions. The authors have determined the modes of collision of droplets of suspensions (coagulation and separation) and the main characteristics of secondary fragments and constructed the maps of the modes of interaction of drops of suspensions with each other when varying the concentration of solid particles in the suspension, the temperature of the gas-air environment and the time the target drop spent in a gas-air environment with an elevated temperature. The conditions were established for the coagulation of droplets, as well as their intensive secondary grinding to intensify their drying, ignition and combustion in boiler furnaces. It was established that an increase in the temperature of the gas-air environment leads to a significant change in the size and properties of droplets, as well as to the occurrence of oscillatory phenomena in the system. It is substantiated that collision of droplets of suspensions in a gas-air environment with elevated temperature is complex and multi-parametric. Its characteristics depend on a combination of factors (surface tension and liquid viscosity, size and shape of droplets, speed of their movement, density and viscosity of gas-air environment). The authors obtained mathematical expressions to describe the boundaries of the modes of the studied processes and schemes for using the results obtained in order to increase the efficiency of the corresponding technological processes.

Precise arraying of perovskite single crystals through droplet-assisted self-alignment.

Patterned arrays of perovskite single crystals can avoid signal cross-talk in optoelectronic devices, while precise crystal distribution plays a crucial role in enhancing device performance and uniformity, optimizing photoelectric characteristics, and improving optical management. Here, we report a strategy of droplet-assisted self-alignment to precisely assemble the perovskite single-crystal arrays (PSCAs). High-quality single-crystal arrays of hybrid methylammonium lead bromide (MAPbBr3) and methylammonium lead chloride (MAPbCl3), and cesium lead bromide (CsPbBr3) can be precipitated under a formic acid vapor environment. The crystals floated within the suspended droplets undergo movement and rotation for precise alignment. The strategy allows us to deposit PSCAs with a pixel size range from 200 to 500 micrometers on diverse substrates, including indium tin oxide, glass, quartz, and poly(dimethylsiloxane), and the area can reach up to 10 centimeters by 10 centimeters. The PSCAs exhibit excellent photodetector performance with a large responsivity of 24 amperes per watt.

Physics Of Two-Stage Evaporation Of Volatile Droplets Suspended In An Ultrasonic Levitator

The evaporation process of mono-component droplets in an ultrasonic levitator is experimentally monitored, focusing on three types of volatile liquids: methanol, ethanol, and 2-propanol. This investigation reveals a ‘two-stage’ evaporation process characterized by an initial rapid evaporation stage followed by a significantly slower evaporation stage; a pattern consistently observed across all three volatile liquids. However, for droplets of comparable size, methanol droplets evaporate faster in the rapid stage than ethanol and iso-propanol droplets and enter the slow evaporation stage earlier. On the other hand, during the slow evaporation stage, 2-propanol droplets exhibit the lowest evaporation rate compared to methanol and ethanol droplets. To explain the two-stage evaporation and the varying evaporation characteristics of mono-component droplets with different volatile components, the streaming patterns within the levitator, with and without a suspended droplet, are visualized and quantified using Particle Imaging Velocimetry (PIV). Two acoustic-induced jet flows, originating from the transducer and reflector of the levitator and considered as Eckart streaming, are observed within the empty levitator. These jet flows move toward the levitated droplet, influencing its evaporation process. Additionally, Stefan flow, carrying vapor away from the surface of the volatile droplet, is clearly observed due to rapid evaporation. The competition between Stefan flow and Eckart streaming ultimately determines the external streaming patterns around the investigated droplets. A theory combining the external streaming patterns and vapor enrichment is proposed to interpret the two-stage evaporation and the corresponding characteristics of the evaporating droplets suspended in the levitator. Furthermore, this study captures boundary-driven acoustic streaming near the droplet surface, known as Rayleigh–Schlichting streaming, whose dimensions and motion vary with the different liquid components and the properties of the corresponding vapor. In summary, the study highlights the presence of Eckart streaming in the ultrasonic levitator and Stefan flow outside an evaporating volatile droplet. Considering these flow patterns is essential for explaining the ‘two-stage’ evaporation and the relevant characteristics within the ultrasonic levitator.

The investigation of lecithin and cocamide DEA Biosurfactant concentrations on emulsified biodiesel fuel stability, properties, and the micro-explosion phenomenon

Water-in-diesel emulsion (WIDE) fuel has been employed to reduce the emissions from diesel engines. Emulsified fuel in combustion chamber experiences secondary atomization, leading to micro-explosions that lower the combustion temperature and improve atomization. As a result, it reduces emissions and improves combustion efficiency. Emulsified fuels often face challenges with water separation over time; therefore, chemical surfactants have traditionally been used to prevent water separation from emulsified fuel. While biosurfactants offer a more environmentally friendly option compared to traditional chemical surfactants, there is a research gap regarding use of emulsified fuel with biosurfactant. This study aims to investigate the effect of biosurfactant concentration on emulsified fuel properties, stability, particles size, and microexplosions. In this study, six emulsified biodiesel fuels were developed with 10 % distilled water and biosurfactants (lecithin 63 % and cocamide DEA 37 %) ranging from 0.5 % to 3.0 %. The emulsion stability and properties of these fuels were examined. Further, Microscopy was employed to examine particle sizes distributions and suspended droplets hot plate technique with high-speed camera was used to record the micro-explosions. The results illustrate increase in biosurfactant concentration in emulsified fuel increases density and viscosity while reducing surface tension, droplet size, and micro-explosion peak temperature.

Strategic ventilation design for reducing airborne infection transmission in a two-story building: A numerical approach

This study employs Computational Fluid Dynamics (CFD) to assess the impact of various ventilation configurations on respiratory droplet dispersion in a two-story restaurant building, aiming to reduce airborne infection transmission. A total of 24 scenarios, involving three ventilation configurations and eight individuals as potential droplet sources, are studied. The configurations—Case A, Case B, and Case C—are analyzed for their effectiveness in controlling droplet dispersion and improving air exchange effectiveness (AEE). Case B, with an outlet near occupants and an inlet above the zone separation, proved most effective in minimizing the droplet transmission between floors, reducing suspended airborne droplets on each floor, and preventing surface contamination, thereby enhancing indoor air quality. Despite the positioning inlet and outlet vents near crowded areas, Case A falls short in effectively removing droplets due to the intricate airflow patterns caused by air diffusers. Case C showed larger AEE but was less effective in droplet dispersion control, indicating a crucial balance between optimizing air circulation and limiting pathogen dispersion is needed. The findings underscore the importance of strategic ventilation design in mitigating airborne infection transmission in multi-level buildings. An optimal configuration, as demonstrated by Case B, combines efficient air distribution with strategic placement of ventilation components to create barriers against interzonal droplet transmission. This study highlights the potential of targeted ventilation strategies to significantly reduce the risk of airborne infection in enclosed, populated spaces.