Vivian "Vob" O'Brien, a former principal researcher at the Johns Hopkins Applied Physics Laboratory who conducted pioneering research in the field of fluid mechanics, died Dec. 24 of complications from dementia at Hart Heritage Estates, an assisted-living facility in Street.
The former longtime Northeast Baltimore resident was 86.
Dr. O'Brien was born in Baltimore, the daughter of a clerk and a homemaker, and raised on Northway Drive.
After graduating in 1941 from Eastern High School, she earned a bachelor's degree in mathematics in 1945 from Goucher College. She then considered a career as a math teacher.
Though there were few opportunities for young women in science at the time, the manpower shortage of World War II made it possible for her to take a job as a junior aerodynamicist at the old Glenn L. Martin Co. plant in Middle River.
"When they needed aerodynamic calculations in a hurry, young candidate O'Brien was available. With slide rule and desk calculator she was soon solving equations affecting pioneering space developments such as the HASR (High Altitude Sounding Rocket), which turned out to be the granddaddy of the Navy's now historic Vanguard," said a 1962 profile in The News, a publication of the Johns Hopkins Applied Physics Laboratory.
"At this time supersonic aerodynamics was in its infancy, and Miss O'Brien's first contact with the field stemmed from experiments in which an extra wing for test purposes was affixed to a fighter aircraft which could reach Mach 8 in a steep dive," according to the profile.
After the war, Dr. O'Brien turned her attention to studying unsteady supersonic aerodynamics and turbulence, which had far-reaching consequences for both scientists and airplane designers.
From 1947 to 1955, she was a research staff assistant at the Johns Hopkins University's department of aerodynamics.
It was Dr. O'Brien's analysis and wind tunnel experiments that led to categorized measurements and a greater understanding of unsteady air or turbulence.
Dr. O'Brien earned a master's degree in math from Hopkins in 1950, and earned a second master's degree in engineering aeronautics, also from Hopkins, in 1954.
In 1955, she joined the Applied Physic Laboratory's Eisenhower Research Center in Laurel, where she spent the next 31 years until retiring in 1986 as the center's principal staff physicist.
She was the first female APL staffer to earn a doctorate, which she received in 1960 in fluid mechanics from Hopkins.
She was also fluent in French and could read German and French.
During her APL career, Dr. O'Brien concentrated her research in transonic aerodynamics, magnetohydrodynamics, visual perception, biomedical engineering and fluid flow studies.
"Her ability to offer insightful criticism from a sound base of mathematical and physical knowledge caused her to be sought after for advice from diverse areas around the Laboratory," read an APL tribute at the time of her retirement.
"Dr. O'Brien's investigations of visual effects uncovered the so-called Craik-O'Brien-Cornsweet illusion in the perception of brightness. Vivian fascinated audiences with her presentation and demonstration of slow unsteady motions in the transport of bubbles, drops, and other fluid blobs," said the tribute.
"She did fundamental research in fluid mechanics and in 1958 wrote a paper on vision and our perception of contours that was published in 1958 in Journal of the Optical Society of America," said Russell McCally, who had shared an APL office with Dr. O'Brien.
"I truly respected her work as a mathematician and in fluid mechanics," he said. "She was a warm and friendly person but a no-nonsense one. I don't think she suffered fools gladly."
A Girl Scout in her youth, Dr. O'Brien remained involved as a volunteer and troop leader for more than 70 years.
Naomi I. Carter had been a member during the 1960s of Girl Scout Troop 219 in Northeast Baltimore, for which Dr. O'Brien and her close friend, M. Jane Scheller, both served as troop leaders.
"She was definitely a trailblazer. She was an independent woman, which was not very common at the time," said Ms. Carter, who remained a close friend through the years.
"She urged us to be the best that we could and was very passionate about that. She also gave us a lot of living skills and encouraged us to try things out," Ms. Carter said. "She also wanted to give back to the community and made sure our troop was service-oriented. I remember we sent cookies and wrote letters to soldiers who were serving in Vietnam during the war."
While very accomplished professionally, Dr. O'Brien never "talked down to us," Ms. Carter recalled.
"She knew more than my brain could handle at the time. I remember asking what she did at the APL and not understanding her answer. She was such a knowledgeable person," Ms. Carter said, laughing.
"She was a very humble person who didn't broadcast her accomplishments or awards. In fact, she kept her diplomas and awards in the mailing tubes in which they arrived in a chest of drawers unframed," Ms. Carter said. "She never celebrated her celebrity."
"She was my Girl Scout leader in the 1950s," said Luella T. Boin of Bel Air. "Several years ago, she was awarded the Evergreen Award by the Girl Scouts of Central Maryland for her lifetime of service, which was more than 75 years."
Dr. O'Brien and Ms. Scheller, who had become friends while youngsters attending a Girl Scout camp in Pennsylvania, lived together in later years. Since 2006, Dr. O'Brien had been a resident of the assisted-living community in Street.
"Ms. Scheller died Thursday, two weeks after her friend," Mrs. Boin said.
Dr. O'Brien was a world traveler who enjoyed photography, sailing, canoeing and hiking. She also had hiked much of the Appalachian Trail during her lifetime.
She was a communicant of St. Luke Evangelical Lutheran Church in Parkville.
A memorial service was held Jan. 2.
She had no close surviving relatives.