Session: Research Posters

Paper Number: 119998

119998 - Influence of Effective Length on the Directional Motion of Leidenfrost Droplets in Micro-Scale Ratchets 

IThis study aims to understand the underlying mechanisms governing the motion of Leidenfrost droplets on patterned surfaces, and investigates how the effective length of the ratchet structure impacts the droplet's dynamic characteristics. The findings of this study contribute to the advancement of science and engineering by providing insights into the manipulation and control of Leidenfrost droplets for various microfluidic and heat transfer applications.

Motivation and Purpose: Leidenfrost droplets have shown promising potential in microfluidics, heat transfer, and self-cleaning surfaces due to their unique behavior on hot surfaces. The ability to control and guide the motion of Leidenfrost droplets is crucial for harnessing their benefits in these applications. However, a comprehensive understanding of the factors influencing their motion, particularly in micro-scale ratchets, is lacking. This research aims to fill this knowledge gap by investigating the influence of effective length on the directional motion of Leidenfrost droplets.

Contribution to Science and Engineering: The primary contribution of this work is the exploration of the role of effective length in determining the kinematic quantities of Leidenfrost droplets on micro-scale ratchets. By elucidating the underlying mechanisms, this study provides valuable insights for the design and optimization of surface structures to manipulate Leidenfrost droplets. These findings advance the scientific understanding of droplet dynamics and contribute to the development of efficient microfluidic systems, heat transfer devices, and self-cleaning surfaces.

Methodology: We experimentally investigated the directional motion of Leidenfrost droplets on micro-scale ratchets with varied ratchet period from 150 micrometer to 750 micrometer. We manipulated the effective lengths below Leidenfrost droplet on micro-ratchets in two different methods 1) by varying ratchets depth while maintaining same ratchets period and 2) creating an incline 15 degree above the horizontal. A custom-designed experimental setup was used to provide a controlled environment for observing droplet behavior. Metal-based micro-scale ratchets with varying effective lengths are fabricated using microfabrication techniques including micromilling, hot embossing, electroplating, water-jet cutting, and post-planarity procedures. High-speed camera was employed to capture the motion of Leidenfrost droplets, allowing for detailed analysis of their dynamics. The experimental data is complemented by analytical modeling to gain further insights into the underlying physics.

Preliminary Results and Conclusions: Preliminary experimental results reveal a clear correlation between the effective length of droplet over the ratchets and the directional motion of Leidenfrost droplets. Shorter effective lengths tend to induce less mobilities of droplets, whereas longer effective lengths exhibit more dynamic enough to faster speed even on 15 degree inclined ratchets. The analytical modeling provides a qualitative understanding of the phenomena observed in the experiments. Based on these findings, it can be concluded that the effective length of Leidenfrost droplet over the micro-scale ratchets significantly influences the dynamics of droplet propulsion.

In summary, this research investigates the influence of effective length on the directional motion of Leidenfrost droplets in micro-scale ratchets. By providing insights into the underlying mechanisms, this study contributes to the scientific understanding of droplet dynamics and offers opportunities for the design of efficient microfluidic systems, heat transfer devices, and self-cleaning surfaces. Further experimentation and analysis are underway to validate and expand upon these preliminary findings, with the goal of advancing the field of droplet manipulation in micro-scale systems.

Presenting Author: Jeong Tae Ok NA

Presenting Author Biography: Dr. Jeong Tae (JT) Ok has a diverse background including Mechanical (BS and PhD), Electrical (MS), Electronic (ME), Chemical & Petroleum Engineering (Postdoctoral). He obtained his PhD in the interdepartmental Mechanical and Electrical Engineering programs in Engineering Science at Louisiana State University, Baton Rouge (May 2011). His research has been particularly oriented in the geometrical effects on fluid transportation in micro- and nanofluidics. His doctoral graduate study (supervised by Prof. Sunggook Park) focused on liquid droplet motion on miniaturized asymmetric geometries in extreme-water-repellent conditions such as Leidenfrost (or film-boiling) and superhydrophobic regimes. Before joining the Department of Engineering Technology at Shawnee State University, he was a tenure track Assistant Professor (Mechanical Engineering) at Midwestern State University (MSU Texas). He was a postdoctoral researcher (supervised by Prof. Keith B. Neeves, Chemical & Biological Engineering; and Prof. Xiaolong Yin, Petroleum Engineering) at Colorado School of Mines where he made significant contributions in the field of petroleum fluids transport within artificial porous media analogs while working on RPSEA (Research Partnership to Secure Energy for America) joint project between Colorado School of Mines and Missouri University of Science and Technology. Dr. Ok has been expanding his research subjects such as computational thermo-fluidics; design and hardware implementation of the apparatus for the application of biology, petroleum, energy, and heat transfer; machine learning with humanoid robot via the undergraduate research and senior design projects at MSU Texas. His long-term research goal is to contribute in micro- and nanofluidics based thermo-fluidic/biomedical engineering and deep learning oriented biomechanical engineering/design and smart manufacturing while also pursuing extension of his previous and current research. He has 11 refereed journal publications and more than 40 conference presentations including 17 refereed international conference proceedings.

Authors:

Jeong Tae Ok NA
Sunggook Park Louisiana State University
Sheldon Wang Midwestern State University