Ni selected for an NSF CAREER to explore deformable particle dynamics in turbulence

March 1, 2017

UNIVERSITY PARK, Pa. – Rui Ni, assistant professor of mechanical engineering and director of the Fluid Transport Lab at Penn State, has been awarded a selective National Science Foundation (NSF) Early Career Development (CAREER) award to further understanding of the behavior of deformable liquid droplets or gas bubbles in turbulent flow, the most common state of fluid motion in nature, yet the least understood.

Pure liquid or gas is difficult to find in nature; most co-exist with some small particles in a different phase. For instance, air and water are mostly seeded or contaminated with dust particles, biomass, bubbles or droplets. Those flows with more than one phase (air, solid, or liquid) are often referred to as multiphase flow.

“I’m extremely honored and grateful to receive this NSF CAREER award,” Ni said. “This will help our Fluid Transport Lab to establish a new framework to discover the hidden dynamics in turbulent multiphase flow. This will pave the way for high-fidelity predicative simulations for multiphase processes.”

Being able to predict the behavior of multiphase flows will have real-world impacts on industries in which they are common, such as power generation, aerospace, marine, chemical, food and beverage and biotechnology. The ability to simulate and predict multiphase flows is desirable because it may increase safety and efficiency, boost production or reduce particle emissions, among other benefits.

While there are several types of multiphase flows, Ni will research a relatively understudied type, one containing deformable particles of liquid droplets or gas bubbles. These particles can freely deform, tumble, break up and coalesce in turbulent flow, adding new degrees of complexity to an already complex problem.

Ni said the lack of research in this area attracted him.  “Many simulations assume bubbles are spherical and rigid, even when they are not. That’s why we want to use our facility to examine how deformability changes the flow physics and figure out how we can predict it.”

The five-year grant for $500,000 will support Ni’s proposal, “Multiscale Experimental Framework on Dynamics of Deformable Particles in Turbulent Dispersed Multiphase Flow.”

Key to the experimentation will be Ni’s vertical water tunnel facility, Vertical Octagonal Noncorrosive Energetic Turbulence (V-ONSET), a 9-foot-tall apparatus in Ni’s Fluid Transport Lab that contains flowing water and bubbles of air or droplets of other liquid in a controllable environment. By altering the speed of the flowing water, the size of the bubbles or droplets, and other factors, Ni can study how deformable particles behave under different conditions inside his V-ONSET system.

In the classroom, Ni’s CARREER award supports a multi-disciplinary teaching collaboration dealing with the emerging concept of STEAM — Science Technology Art and Math. An extension of the common STEM acronym, STEAM is aimed at acknowledging and promoting the idea that art and design have a place in innovation.

To this end, Ni and Ian Brill, an instructor in the College of Arts and Architecture School of Visual Arts have created a shared undergraduate course project called Art-Fluid. Brill’s students will team up with Ni’s Fluid Flow students to work on projects that explore both the scientific and visual properties of fluid. Stephanie Cutler, assessment and instructional support specialist in the Leonhard Center for Enhancement of Engineering Education, will help to assess how this new STEAM framework can help with students’ creativity.

“We want our students to engage in a multidisciplinary environment that promotes critical thinking from a different perspective— for the engineering students to learn about the visual appeal and for the art students to learn about the engineering,” Ni said. “We will ask the students to work together on a project involving fluid flow. Hopefully at the end of the semester, they have an artistic project that also helps to explain the science.”

Ni joined the Mechanical and Nuclear Engineering Department in 2015 through co-funding from the Institute for Natural Gas Research at Penn State. He received his doctorate in physics from the Chinese University of Hong Kong in 2011 and his bachelor’s degree in applied physics from Hefei University of Technology, China. Ni’s doctoral research focused on turbulent thermal convection. Prior to coming to Penn State, he held a joint postdoctoral research associate position at Yale University and Wesleyan University. His research interests include Lagrangian particle tracking, transport of fluid (petroleum and natural gas) in complex environments, turbulent thermal convection, fiber flow, and thermal energy management.


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Chris Hennessey

Fluid Transport Lab members

Assistant professor Rui Ni, left, with his Fluid Transport Lab team. In the front row, from left, are senior Rabin Subedi and master’s student Zeynep Kaymak. In the back row, from left, are doctoral student Ashwanth Salibindla and master’s student Gökhan Akarslan.

V-ONSET vertical water tunnel

The V-ONSET vertical water tunnel is the centerpiece of Ray Ni’s Fluid Transport Lab. With it, he can create exact conditions for studying turbulent flows.

“Many simulations assume bubbles are spherical and rigid, even when they are not. That’s why we want to use our facility to examine how deformability changes the flow physics and figure out how we can predict it.”

–Rui Ni



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