(October 31st, 2019)

Dr. CJ Kim will be addressing students at 4:00 pm in 246 CB.

Professor CJ Kim received his B.S. from Seoul National University, M.S. from Iowa State University, and Ph.D. from the University of California at Berkeley and joined the faculty at UCLA in 1993. Holding Distinguished Professor title and the Volgenau Endowed Chair in Engineering, he performs research in micro electro mechanical systems (MEMS) with a focus on utilizing surface tension. The recipient of Research Excellence Award (Iowa State Univ.), TRW Outstanding Young Teacher Award (UCLA), NSF CAREER, ALA Achievement Award, Samueli Outstanding Teacher Award (UCLA), ASME Fellow, and Ho-Am Prize in Engineering, Prof. Kim has served as General Chair of the 2014 IEEE International Conference on MEMS. He is currently serving on several editorial boards including IEEE Journal of MEMS.

 

When watercraft travels in water, drag impedes its motion, consuming energy and limiting speed. Considering the worldwide impact, drag reduction by even a small fraction would have a considerable benefit. Because skin friction is typically the largest portion of the total drag, numerous methods have been explored for decades to reduce the skin friction. However, none has been effective enough for wide acceptance. Superhydrophobic (SHPo) surface has been receiving significant attention since early 2000s because the gas layer on its surface (called plastron) can lubricate the water flow and reduce skin friction. Despite the significant advancement in research, however, SHPo drag reduction has not been obtained for the most coveted conditions, i.e., high Reynolds number flows in open water. This talk will present the first successful large drag reductions (~30%, up to ~40%) on the sea, confirmed with credit-card-size SHPo samples attached under a motorboat and subjected to Reynolds number as high as 1.14x107 (friction Reynolds number 5800).