On Oct. 14, Dr. Mohamed Gad-el-Hak, the Inez Caudill Eminent Professor of Department of Mechanical & Nuclear Engineering, Virginia Commonwealth University in U.S.A, presented a seminar titled “Nine Decades of Fluid Mechanics” to the College of Engineering, Peking University. Prof. Cunbiao Lee, director of the Department of Aerospace Engineering hosted the talk.
As the American Society of Mechanical Engineers Division of Fluids Engineering celebrates its 90th anniversary, Dr. Mohamed Gad-el-Hak made a broad-brush sweep of progress in the field of fluid mechanics during this period.
“Fluid is the most important state which occupies over 99.99% in Universe. The ASME hydraulic division was started in 1926 and changed to Fluids Engineering Division in 1962. Nine decades have passed since 1926,” he mentioned.
He pointed out that there are four golden ages prior to 1926. The first one is some 2000 years ago. At that time, Archimedes measured the body volume by measuring the fluid volume the body occupies. Roman’s aqueducts were also amazing. These two examples are fluid applications based on knowledge of hydrostatics. The second stage is the time Leonardo da Vinci (1452-1519) lived. Leonardo made detailed flow visualization in an art manner and maybe the first one to (accurately) describe the eddying motions and vortices. The third stage is started by Newton. At that stage, Navier-Stokes equations were found and prefect flow theory was built. The fourth stage begins with the boundary layer theory proposed by Prandtl (1904). Boundary layer theory resolved the long-existed conflict between hydrodynamics and hydraulics. Later, Richardson (1881-1953) made the first weather prediction in 1920, taking six weeks to compute a six-hour forecast. His prediction, however, was totally wrong.
Dr. Mohamed Gad-el-Hak then turned to the last nine decades. He said that the computer and laser were the greatest inventions in the last 90 years and perhaps even ever. Along with these two inventions, many theoretical, experimental and numerical advances have been achieved.
The speech lasted about one hour. In the discussion session, Professor Cunbiao Li asked, “Will there be any big progress of fluid mechanics in the future?” Professor Gad-el-Hak answered, “Although fluid mechanics is one of the oldest science, quantum progress might also occur, since people has many big problems to solve. For example, it took passengers 14 hours to fly from Washington D.C. to Beijing. Is there any possibility to build a hypersonic vehicle so that it only takes two hours? Such is the big driven force to make great achievements in fluid mechanics in the future.”