(7hm) Multiphase Interactions to Create Designer Material

3^rd Year Postdoctoral Fellow

PhD Dissertation: Dynamics of droplet shedding and coalescence under the effect of shear flow.

Under supervision of Prof. Nabil Esmail and Prof. Ali Dolatabadi, Department of Mechanical Engineering, Concordia University, Montreal, Canada.

1^st Postdoctoral Project: Study of droplet impact and shedding on laser treated substrates.

Under supervision of Prof. Anne Kietzig, Department of Chemical Engineering, McGill University, Montreal, Canada.

2^nd Postdoctoral Project: Study of unit operations and material characterization involved in continuous manufacturing of solid dose pharmaceutical products.

Under supervisor of Prof. Fernando Muzzio. Department of Chemical and Biochemical Engineering, Rutgers University, NJ, USA.

Research Experiences:

During my academic career, I was involved in various engineering fields from fluid dynamics to pharmaceutical unit operations. My former training in PhD and first postdoctoral fellowship was in experimental and computational fluid dynamics and surface engineering. Where I learned various simulation techniques such as Volume of Fluid and Smoothed Particle Hydrodynamics in addition to experimental techniques in shadowgraphy and laser micromachining. During my second postdoctoral fellowship, I was involved in characterizing pharmaceutical unit operations where I acquired invaluable experiences in pharmaceutical manufacturing, unit operations, and material characterization.

Research Interests:

The general theme running through my research activities is my great interest in multiphase interactions and surface engineering. My goal is to establish a topnotch multiphase flow and surface engineering research program emphasizing their practical applications in various engineering fields. I have found that I greatly benefit from working on multidisciplinary projects. I enjoy bringing together individuals with different backgrounds and approaches, to allow them to spark off novel perspectives. In this respect, I have collaborated with researchers from many different fields. My research objectives are to take advantage of theoretical, computational, and experimental tools for better understanding of the multiphase interactions. My emphasis is always to convert the knowledge obtained into successful designs with a wide range of engineering applications.

My immediate research plans that follow from my Ph.D. and postdoctoral research work can be categorized as follows.

Droplet dynamics:

Droplets interactions with substrates involve in variety of industrial applications from ink-jet printing to rain impingement (and consequential icing phenomenon) on structural systems like power-lines, wind turbines and airfoils. During my PhD and first postdoctoral fellowship, I performed a fundamental experimental and numerical study on droplet dynamics. I investigated the effect of surface wettability and air flow speed in predicting the drop behavior in terms of shedding and coalescence. I showed that on a hydrophilic substrate (providing high enough air speed), narrow streams of liquid were formed from merging droplets. In contrast, on a superhydrophobic substrate coalesced droplets rolled on the surface and detached from it when the air speed was sufficiently high. In addition, the results indicated a contrast in the mechanism of the coalescence and subsequent detachment between a single and two droplets on a superhydrophobic surface. At low air speeds, the two droplets coalesced by attracting each other before detaching with successive rebounds on the substrate, while at higher speeds the detachment occurred almost instantly after coalescence, with a detachment time decreasing exponentially with the air speed. The experimental results were also compared with the results of numerical simulation based on Volume of Fluid method to give a better understanding of the phenomena by analyzing the aerodynamic forces, velocity vectors, and stream lines on the droplets.

In continuation of this work, I would like to investigate the effect of liquid viscosity and surface tension in droplet behavior in terms of shedding, impact and coalescence. I am also interested in studying the effect of surface and ambient temperature on droplets dynamics, specifically, in freezing conditions. There, the heat transfer equations will play an important role in modelling the system’s dynamic. Solidification has various potential applications from icing to surface coating with thermal spray techniques where molten particles with high velocity hit the target surface and solidified on it. Investigating the effect of droplet size (sub-micro droplets) can be another interesting topic for research. There, the pillar size (micro and nano structures) existed on substrates becomes comparable with the size of the droplet. Therefore, the effect of surface roughness on the droplet dynamics should also be included in the experimental and numerical analyses.

Thermal spray process to create durable superhydrophobic surfaces:

Thermal spray techniques are used extensively in aerospace, automotive, and power generation industries to provide protective coatings on engine, landing gear, and turbine components that are exposed to heat, corrosion, and wear. It is also found that the suspension plasma spray technique has the potential to be used as a suitable method for creating durable superhydrophobic coatings. This approach is much more affordable compared to other techniques such as laser etching. Superhydrophobic coatings can be used to generate waterproof, anti-corrosive, and anti-icing surfaces. These surfaces can also be used as protection in circuits and grids due to their self-cleaning properties. In aerospace industries, these surfaces are used to reduce the drag force and increasing the speed which lead to higher efficiency. However, the durability of the superhydrophobic coatings is generally weak today due to their delicate micro and nano structures. This is the main reason that limit their applications. During my collaborative work in “Thermal Spray Lab” at Concordia University, I grasped knowledge in thermal spray processes and their applications. Therefore, due to my interest in wetting science, I am interested in a detailed study on applying thermal spray techniques to generate durable superhydrophobic coatings.

Wettability of granular materials:

Granular materials are widely used in various industries such as pharmaceuticals, food, agricultural chemicals, detergents, and catalysts. Wetting properties of both raw and processed material is one of the significant characteristics involved in various process steps from formulation development to the design of manufacturing pathway. It is known that granules’ wetting properties will change significantly while undergoing different manufacturing processes. It is also known that granules’ wettability affects their dissolution performance which can be a significant aspect for industries such as pharmaceuticals. Therefore, knowing the wetting properties of granular material is inevitable for quality control in advanced pharmaceutical manufacturing. Having closely worked with pharmaceutical industries during my postdoctoral fellowship at Rutgers, and considering my background in wetting science, I am passionate to carry on research on developing experimental and numerical methods to characterize granular material wettability. Together with the wettability analysis, I am also interested in doing research on droplet impact dynamics on porous material.

Teaching Experiences:

In the middle of my third year of undergraduate studies I became an instructor for teaching engineering software. It was initially a huge challenge for me to prepare the lecture, and develop exam questions. However, I truly enjoyed teaching and seeing how my students learned from me. I received good feedback from the attendees. This first experience encouraged me to continue working as a teaching assistant and guest lecturer for six years through my master as well as during my PhD. Again, I received good feedback not only from the main instructors of those courses, but also from the students. Currently, as an adjunct lecturer and postdoctoral fellow at Rutgers University, I am supervising various students, who are working towards their thesis projects. Due to my passion for teaching, alongside my research, I teach one course each semester.

Teaching Interests:

Having a strong background in engineering, I have the experience and knowledge to teach basically all fundamental chemical and mechanical engineering courses. Particularly, if assigned to me, I would be excited to teach: at the undergraduate level: unit operations, reaction engineering, fluid mechanics, heat and mass transfer, thermodynamics, statics, dynamics, computer fundamentals, numerical methods, and engineering mathematics; at the graduate level: advanced fluid mechanics, computational fluid dynamics, advanced heat and mass transfer.

Furthermore, I would be thrilled to develop a course on the graduate level that is more closely related to my field of research including but not limited to the theory and application of multiphase flows which introduces students into the various techniques and processes that emerged recently at the forefront of research. Apart from familiarizing students with different techniques, they would be required to come up with their own application ideas as part of a course project. This course would not only encourage interdisciplinary thinking and team work, but also will attempt to trigger new research and applications in one of the core engineering research fields.