MAE postdoctoral researcher Dr. Chi-An Yeh, mentored by MAE Professor Sam Taira, is a recipient of the  2020-21 Chancellor’s Award for Postdoctoral Research. He is among 11 recipients of this award at UCLA this year.

Research Abstract

The designs of modern-era aerodynamics are facing unseen challenges from those in the past. Human exploration of Mars, as one of the biggest aerospace challenges for the next decade, exploits air vehicles designed for a completely different operational regime from that on Earth. Moreover, the development of personalized urban flights, which is foreseen to revolutionize urban transportation and logistics, requires transcendent flight capability with gust rejection as well as highly agile and safe maneuvers. These new requirements for new operational regimes and unsteady operational environments have shifted the paradigm of aerodynamic analyses. In addition to controlling the vehicles, aerodynamicists need to consider the control of flow around them to meet the new performance requirements.

In the Department of Mechanical and Aerospace Engineering at UCLA, Dr. Chi-An Yeh’s postdoctoral research efforts focus on innovative active flow control technologies. In this multidisciplinary research field, Dr. Yeh dedicates his efforts to the intersection of fluid mechanics, data science, and network science. With the creative combinations of these novel tool sets, he has developed flow control strategies for unsteady aerodynamic applications. His flow control techniques improve operational safety of air vehicles by suppressing wing stall, which accounts for almost 25% of all fatal flying accidents. They are also developed to reduce the drag and enhance fuel efficiency that translates to billions of dollars of savings in fuel cost, reduced carbon emission and cleaner air. These techniques are also critically needed for the development of personalized urban flights to revolutionize future transportation.

At UCLA, Dr. Yeh’s research relies on computational methods that are known to be prohibitively expensive for fluid-flow problems. To make flow control realizable, he developed algorithms based on data science to relief the computational cost of theoretical and numerical analyses to help understand dynamical properties of fluid-flow systems. He also innovatively combined network science with flow control analysis to tame turbulence, which is recognized as the last unsolved problem in classical physics. At UCLA, he forged collaboration with researchers from the Air Force Research Laboratory to develop a guideline for flow control design that aims to suppress flow separation at a highly complex flow regime. He also worked with scholars from Tokyo University of Agriculture and Technology to study the transonic buffet phenomenon that must be avoided during Martian flights.