Rui Ni: Physics, Fluids, and Bubbles

September 17, 2018

New faculty member Rui Ni aims to deepen our understanding of fluid dynamics from a physicist’s perspective.

Fluid dynamics is of paramount importance not only to understand biological processes like blood flow and breathing, but also in designing devices and industrial processes that play a critical role in our daily lives. Everyday tasks such as boiling water, driving cars, and running your air conditioner are examples of fluid dynamics in action.

Rui Ni, a new assistant professor of mechanical engineering at Johns Hopkins University, hopes to deepen our understanding of fluid dynamics from a physics perspective.

Ni’s research focuses on the fundamental science of turbulence and multi-phase flows that involve more than one phase (i.e. liquid, solid, or gas). Such research has applications in next-generation energy systems, environmental engineering, and physiological flows in the human body.

“Most energy systems rely on multi-phase flows. For example, in the boiling process, bubbles detached from a heated surface are constantly deforming, but surprisingly models after many years of development still have a hard time to predict even this simplest phenomenon. As an experimentalist, I am interested in revealing the physics involved in this process by designing an advanced visualization system to reconstruct the deformation of bubbles inside turbulence,” says Ni.

Scientists have long studied the behavior of fluids under various conditions to explore new applications. According to Ni, now is a unique and exciting time to be working in fluid dynamics.

“We have many new tools, like high-speed cameras, LED systems, and other cool gadgets that we didn’t have access to five or 10 years ago. With these tools, we can track objects with unprecedented concentration and resolution, and we start to resolve the dynamics occurring at different scales—from micro-sized bubbles all the way to the system scale. This offers us new insights into problems, and the results can help us design models with better predictions” he says.

Ni joins Johns Hopkins from Penn State University, where he held the Kenneth Kuan-Yun Kuo Early Career Professorship in mechanical engineering. Ni earned his PhD in physics from the Chinese University of Hong Kong in 2011, and worked as a postdoctoral scholar at Yale University and Wesleyan University before joining Penn State in 2015. In 2017, he received the NSF CAREER Award in fluid dynamics and the ACS-PRF New Investigator Award.

Because the Department of Mechanical Engineering is home to a world-renowned fluids group with expertise in a range of areas, Ni considers Johns Hopkins the ideal place to continue and advance his research. He looks forward to collaborating with leading players in his field, including fellow experimentalist, Joseph Katz.

“Hopkins has a long history of groundbreaking research in fluid dynamics. I came across a lot of Hopkins work as a graduate student, and I always wondered what the Hopkins environment looks like. And now I’m excited to experience it firsthand.”



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