Study on the formation and separation process of droplets in the medical piezoelectric atomization device induced by intra-hole fluctuation

Abstract Oral inhalation of aerosolized drugs can be directly performed on the affected body organs including lesions of the throat, trachea as well as lungs. As compared to the other conventional therapies such as intravenous drip, intramuscular injection and external topical administration, this novel technique can greatly reduce the dosage and side effects of drugs. However, the traditional atomization devices always exhibit many drawbacks, such as wide spreading distribution of atomization particle size, the instability of transient atomization quantity and difficulties in precise energy control, which seriously restrict more extensive application of atomization inhalation therapy. The formation and separation process of droplets is a microphenomenon of atomization. Research on the droplet formation and separation process will help us to better understand the atomization mechanism. In present work, the Conservative Level Set Method (CLSM) is the first time to be applied on the simulation of the formation and separation of droplets in a medical piezoelectric atomization device induced by intra-hole fluctuation. The intra-hole fluctuation mechanism is analyzed in details, and also the expression of the volume change of the micro cone hole is evaluated. The control equation and simulation model of droplet formation and separation process has been well established by meshing the simulation model, and thereby the process of droplet formation and separation is simulated. The corresponding results demonstrate that the breaking time of droplets decreases with the increase of inlet velocity and liquid temperature, and increases with the increase of liquid concentration. Meanwhile, the volume of droplet decreases with the increase of inlet velocity and liquid concentration, but increases with the increase of liquid temperature. The velocity of droplet is enhanced with the inlet velocity and liquid temperature rising, and reduced with the increase of liquid concentration. When the large side diameter of micro-cone hole is set as 79 μm, the breaking time of the droplet reaches a minimum value of 38.7 μs, whereas the volume and the velocity of droplet reaches a maximum value of 79.8 pL and 4.46m/s, respectively. This study reveals the atomization mechanism of the medical piezoelectric atomization device induced by intra-hole fluctuation from a micro perspective . It provides theoretical guidance for the design of medical piezoelectric atomization devices and contributes to the promotion of inhalation therapy in practical use.

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Numerical Investigation for the Resin Filling Behavior during Ultraviolet Nanoimprint Lithography of Subwavelength Moth-Eye Nanostructure

Coatings ◽

10.3390/coatings11070799 ◽

2021 ◽

Vol 11 (7) ◽

pp. 799

Author(s):

Yuanchi Cui ◽

Xuewen Wang ◽

Chengpeng Zhang ◽

Jilai Wang ◽

Zhenyu Shi

Keyword(s):

Simulation Model ◽

Nanoimprint Lithography ◽

Cfd Simulation ◽

Boundary Slip ◽

Accurate Analysis ◽

Inlet Velocity ◽

Filling Height ◽

Proposed Model ◽

Good Consistency ◽

Computational Fluid Dynamics Cfd

Accurate analysis of the resin filling process into the mold cavity is necessary for the high-precision fabrication of moth-eye nanostructure using the ultraviolet nanoimprint lithography (UV-NIL) technique. In this research, a computational fluid dynamics (CFD) simulation model was proposed to reveal resin filling behavior, in which the effect of boundary slip was considered. By comparison with the experimental results, a good consistency was found, indicating that the simulation model could be used to analyze the resin filling behavior. Based on the proposed model, the effects of process parameters on resin filling behavior were analyzed, including resin viscosity, inlet velocity and resin thickness. It was found that the inlet velocity showed a more significant effect on filling height than the resin viscosity and thickness. Besides, the effects of boundary conditions on resin filling behavior were investigated, and it was found the boundary slip had a significant influence on resin filling behavior, and excellent filling results were obtained with a larger slip velocity on the mold side. This research could provide guidance for a more comprehensive understanding of the resin filling behavior during UV-NIL of subwavelength moth-eye nanostructure.

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Simulation study of droplet formation in inkjet printing using ANSYS FLUENT

Journal of Physics Conference Series ◽

10.1088/1742-6596/2161/1/012026 ◽

2022 ◽

Vol 2161 (1) ◽

pp. 012026

Author(s):

Neha Thakur ◽

Hari Murthy

Keyword(s):

Ethylene Glycol ◽

Simulation Model ◽

Inkjet Printing ◽

High Viscosity ◽

Droplet Formation ◽

Nozzle Diameter ◽

Print Quality ◽

Ansys Fluent ◽

Low Viscosity ◽

Inkjet Printer

Abstract Flow simulations of jetting of inkjet drops are presented for water and ethylene glycol. In the inkjet printing process, droplet jetting behaviour is the deciding parameter for print quality. The multiphase volume of fluid (VOF) method is used because the interaction between two phases (air and liquid) is involved in the drop formation process. The commercial inkjet printer has a nozzle diameter of ∼73.2μm. In this work, a simulation model of inkjet printer nozzles with different diameters 40μm, 60μm, and 80μm are developed using ANSYS FLUENT software. It is observed that when water is taken as solvent then the stable droplets are generated at 60μm nozzle diameter till 9μs because of its low viscosity. For higher diameter, the stamen formation is observed. Ethylene glycol stable droplets are achieved at 80μm nozzle diameter till 9μs because of their high viscosity (∼10 times that of water). Along with the droplet formation, the sustainability of the droplet in the air before reaching the substrate is also important. The simulation model is an inexpensive, fast, and flexible alternative to study the ink characteristics of the real-world system without wasting resources.

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Effects of Vibration Characteristics on the Atomization Performance in the Medical Piezoelectric Atomization Device Induced by Intra-Hole Fluctuation

Chinese Journal of Mechanical Engineering ◽

10.1186/s10033-021-00635-7 ◽

2021 ◽

Vol 34 (1) ◽

Author(s):

Qiufeng Yan ◽

Wanting Sun ◽

Lei Zhang ◽

Hongmei Wang ◽

Jianhui Zhang

Keyword(s):

Mathematical Expression ◽

Topical Administration ◽

Vibration Characteristics ◽

Mode Shapes ◽

Inhalation Therapy ◽

Laser Vibrometer ◽

Micro Pump ◽

Fluctuation Phenomenon ◽

Oral Inhalation ◽

Atomization Performance

AbstractOral inhalation of aerosolized drugs has be widely applied in healing the affected body organs including lesions of the throat and lungs and it is more efficient than those conventional therapies, such as intravenous drip, intramuscular injection and external topical administration in the aspects of the dosage reduction and side effects of drugs. Nevertheless, the traditional atomization devices always exhibit many drawbacks. For example, non-uniformed atomization particle distribution, the instability of transient atomization quantity and difficulties in precise energy control would seriously restrict an extensive use of atomization inhalation therapy. In this study, the principle of intra-hole fluctuation phenomenon occurred in the hole is fully explained, and the produced volume change is also estimated. Additionally, the mathematical expression of the atomization rate of the atomizing device is well established. The mechanism of the micro-pump is further clarified, and the influence of the vibration characteristics of the atomizing film on the atomization behavior is analyzed theoretically. The curves of sweep frequency against the velocity and amplitude of the piezoelectric vibrator are obtained by the Doppler laser vibrometer, and the corresponding mode shapes of the resonance point are achieved. The influence of vibration characteristics on atomization rate, atomization height and atomization particle size are also verified by experiments, respectively. Both the experimental results and theoretical calculation are expected to provide a guidance for the design of this kind of atomization device in the future.

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