Early Days of Flow Research by J.T. Lin

Early Days of Flow Research Company
By Jung-Tai Lin, Bellevue, WA
September 19, 2013

My first time to meet Dr. Mike Pao was in June 1967, when he came to Colorado State University (CSU) at Fort Collins, Colorado and attended a Symposium on Mountain Meteorology. When he visited the Fluid Dynamics and Diffusion Laboratory of CSU, I was in the middle of doing an experiment to simulate mountain lee waves in a thermally stratified wind tunnel. I was very excited by what he told me about his theoretical and experimental works of stratified flow over mountain and stratified turbulence at the Boeing Scientific Research Laboratories (BSRL).

After receiving my Ph.D. in March 1969, I contacted BSRL, Johns Hopkins University (JHU), National Center for Atmospheric Research (NCAR), and Iowa Institute of Hydraulic Research (IIHR) and applied for a postdoctoral research position. One day, I received a telegram and was afraid to open it. I thought it were a bad news from Taipei because my mother was very ill at that time. But, it was an offer from Dr. John F. Kennedy for a research engineer position at IIHR. The research skills and methodologies I learned from IIHR benefitted me a lot when I started my job at Flow Research Company.

Mike established Flow Research Company in 1970. He called me in November 1970 while I was a postdoctoral scientist with the Advanced Study Program of NCAR at Boulder, Colorado. He asked me to help recruit a research scientist for his brand new company. I referred to him a friend of mine at IIHR, whose Ph.D. dissertation was on grid turbulence in a stratified fluid. Mike called me again in April 1971 and told me that the person, recommended by me, could not join with him. The following day, I flew to Seattle to meet Mike and his wife, Joanne, for an interview in the basement of their house at Normandy Park. After accepting Mike’s offer, I joined with Flow Research on May 27, 1971 as the first full time research scientist. I continued my tenure with Flow Research for seven years till May 31, 1978.

At Flow Research, my first assignment was to construct and test a 60 feet long, 4 feet wide, and 3 feet deep stratified towing tank and its supporting systems, including a stratified fluid filling system, two towing cable systems, and an oil-lubricated instrument carriage. The vibration noise level of the instrument carriage motion was improved to such a minimal that we could accurately measure the turbulent fluctuations of velocity and conductivity. Moving a slender body, towed or self-propelled, in a towing tank was a challenge as Mike and I had not yet gained adequate experience in running a three dimensional body in a towing tank. To find a proper tripping mechanism, in order to ensure that the boundary layer developed along the slender body became turbulent, was another challenge. To investigate the propeller effects on the wake development, I paid several dollars to buy some model propellers from a marine shop at Burien, Seattle. To obtain the self-propelled mode for a propeller-driven slender body was a real challenge.

We developed the towing mechanism to move the slender body in such a way that its interference with the evolution of the body wake was minimized. I came up an idea to tie very thin stainless steel wires to the body and suspended the body from one or two towing cables far enough from the body to minimize the cable disturbances. The slender body was made buoyant so that the sagging of the towing cable(s) in the stratified fluid was compensated and the body moved smoothly.

In late 1971, I observed the two-dimensional horizontal vortices that looked like pan cakes and staggered on the horizontal and vertical planes in the late wake. This was an exciting moment to me because at NCAR I did research on two-dimensional turbulence and derived the exponential growth law of the relative dispersion. At the Flow Research laboratory, I visualized and measured the development of the three-dimensional turbulence in the early wake into the staggered rows of horizontal vortices in the form of “two-dimensional” turbulence in the late wake. This was the highlight of my research life in stratified turbulence.

I very appreciate the opportunity to work with Mike for seven years at Flow Research. I learned from him how to negotiate a research contract, to manage a research project, and to develop people skills in project management. I miss him very much.