(6hh) Effects of Complex Particle Interactions on Fluid-Particle Flows

¹Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08540, USA

Research Interests: My research explores granular electrostatics resulting from contact charging and its effects on flow; and coarse modeling of momentum and scalar transport in gas-particle flows where meso-scale structures arise due to complex fluid-particle and particle-particle interactions, which include van der Waals force, liquid bridge forces and electrostatic interactions. I pursue an integrated approach combining theoretical tools, numerical simulations, and experimental methods. I am also interested in using machine learning techniques to formulate constitutive models for coarse transport equations.

In the future, I intend to continue my research on granular electrostatics and also broaden the scope of my research to liquid-gas flows in trickle beds and liquid-gas flow in porous media. I plan to study these flow problems through lattice Boltzmann simulations, and then formulate constitutive relations for continuum models using machine learning techniques.

Prior Research: Good understanding of gas-solid flows is critical for a wide range of industrial applications ranging from fine laser machining [1] to fluidized beds [2]. For many of these applications, the flows are affected not only by fluid-particle interactions, but also by phase transitions and inter-particle forces. In this poster, I will outline how I have used experimental, theoretical and numerical tools to probe these effects in various systems.

Particle contact charging is a common problem in polyethylene reactors [3], but some applications, such as triboelectric generators [4] and triboelectric separation of fly-ash [5] or municipal waste [6], are based on it. While the underlying physical principals of electrostatic interactions are well understood, the contact charging remains an unsolved problem [7]. I have investigated these effects in fluidized beds and vibrated beds via experimental techniques [8,9] and numerical modeling [10-13] to uncover the underlying phenomena.

Spatter deposition is a major problem in solar panel production where individual elements are separated by a laser. The deposit are usually removed by an assist gas jet in conjuction with the laser head, but optimization of process is challenging due to very small timescale and phase transitions (plasma-gas-solid). I developed 3D particle-tracking-velocimetry (PTV) to capture the spatter movement in 3D space to guide the engineering work [1,14,15].

Teaching Interests: I enjoy greatly helping students learn new concepts and seeing them flourish in their studies. I have a fairly wide educational background ranging from pure mathematics to chemistry, which I believe help in showing students how the topic at hand fits in the larger picture. I have teaching experience in fluid mechanics, heat and mass transfer, thermodynamics, and mathematics classes, all of which have been profoundly enjoyable.

[1] Okamoto, Yasuhiro, et al. "Velocity and angle of spatter in fine laser processing." Physics Procedia 39 (2012): 792-799.

[2] Sundaresan, Sankaran, Ali Ozel, and Jari Kolehmainen. "Toward Constitutive Models for Momentum, Species, and Energy Transport in Gas–Particle Flows." Annual review of chemical and biomolecular engineering 0 (2018).

[3] Hendrickson, Gregory. "Electrostatics and gas phase fluidized bed polymerization reactor wall sheeting." Chemical Engineering Science 61.4 (2006): 1041-1064.

[4] Wang, Zhong Lin. "Catch wave power in floating nets." Nature 542.7640 (2017): 159.

[5] Dwari, R. K., et al. "Studies on the effect of electrode plate position and feed temperature on the tribo-electrostatic separation of high ash Indian coking coal." Advanced Powder Technology 26.1 (2015): 31-41.

[6] Wu, Guiqing, Jia Li, and Zhenming Xu. "Triboelectrostatic separation for granular plastic waste recycling: A review." Waste Management 33.3 (2013): 585-597.

[7] Lacks, Daniel J., and R. Mohan Sankaran. "Contact electrification of insulating materials." Journal of Physics D: Applied Physics 44.45 (2011): 453001.

[8] Kolehmainen, Jari, et al. "Effect of humidity on triboelectric charging in a vertically vibrated granular bed: Experiments and modeling." Chemical Engineering Science 173 (2017): 363-373.

[9] Sippola, Petteri, et al. "Experimental and Numerical Study of Wall Layer Development in a Tribocharged Fluidized Bed." Journal of Fluid Mechanics (2018): Under Review.

[10] Kolehmainen, Jari, et al. "A hybrid approach to computing electrostatic forces in fluidized beds of charged particles." AIChE Journal 62.7 (2016): 2282-2295.

[11] Kolehmainen, Jari, et al. "Triboelectric charging of monodisperse particles in fluidized beds." AIChE Journal 63.6 (2017): 1872-1891.

[12] Kolehmainen, Jari, et al. "Eulerian Modeling of Gas-Solid Flows with Triboelectric Charging." Journal of Fluid Mechanics (2018): Under Review.

[13] Kolehmainen, Jari, et al. "Effects of Polarization on Particle-Laden Flows." Physical Review Letters (2018): Under Review.

[14] Kolehmainen, Jari Tapani, et al. "Measurement of the spatter velocity in fine laser cutting." Proceedings of JSPE Semestrial Meeting 2012 JSPE Spring Conference. The Japan Society for Precision Engineering, 2012.

[15] Viitanen, Timo, et al. "Spatter tracking in laser machining." International Symposium on Visual Computing. Springer, Berlin, Heidelberg, 2012.