John Dabiri

Last updated
John O. Dabiri
John O. Dabiri, PCAST Member (cropped).jpg
Dr Dabiri
Born
Toledo, Ohio
CitizenshipUnited States
Alma mater Princeton University (B.S.E.)
Caltech (Ph.D.)
Known for Vortex formation
Reverse engineering of jellyfish
Applications to wind turbines
Awards PECASE (2008)
MacArthur Fellow (2010)
Alan T. Waterman Award (2020)
Scientific career
Fields Aeronautics
Bioengineering
Mechanical engineering
Institutions Caltech
Stanford University
Doctoral advisor Morteza Gharib

John Oluseun Dabiri [1] is a Nigerian-American aeronautics engineer and the Centennial Chair Professor at the California Institute of Technology (Caltech), with appointments in the Graduate Aerospace Laboratories (GALCIT) and Mechanical Engineering. [2] His research focuses on unsteady fluid mechanics and flow physics, with particular emphasis on topics relevant to biology, energy, and the environment. He is best known for his research of the hydrodynamics of jellyfish propulsion and the design of a vertical-axis wind farm adapted from schooling fish. He is the director of the Biological Propulsion Laboratory, [3] which examines fluid transport with applications in aquatic locomotion, fluid dynamic energy conversion, and cardiac flows, as well as applying theoretical methods in fluid dynamics and concepts of optimal vortex formation.

Contents

In 2010, Dabiri was awarded a MacArthur Fellowship for his theoretical engineering work. [4] He established the Caltech Field Laboratory for Optimized Wind Energy (FLOWE) in 2011, [5] a wind farm which investigates the energy exchange in an array of vertical-axis wind turbines. His honors include a Young Investigator Award from the Office of Naval Research, a Presidential Early Career Award for Scientists and Engineers (PECASE), [3] and being named as one of Popular Science magazine's "Brilliant 10" scientists in 2008. [6] Bloomberg Businessweek magazine listed him among its 2012 Technology Innovators. [7] Since 2021, he has been a member of the President’s Council of Advisors on Science and Technology (PCAST). [8]

Early life and education

Dabiri's parents are Nigerian immigrants, who settled in Toledo, Ohio, in 1975. Dabiri's father was a mechanical engineer who taught math at a community college. His mother, a computer scientist, raised three children and started a software development company. [9] It was watching his father, who would occasionally do engineering work on the side, that encouraged Dabiri's love of engineering. [10]

Educated at a small Baptist high school, where he graduated first in his class in 1997, Dabiri was accepted by Princeton. He was primarily interested in rockets and jets, [11] and spent two summers doing research that included work on helicopter design. The summer after his junior year, he accepted a Summer Undergraduate Research Fellowship (SURF) in Aeronautics at Caltech, [6] rejecting an internship offer from Ford at the urging of a professor. The summer project on the vortices created by a swimming jellyfish enticed him to the growing field of biomechanics. [6]

Dabiri graduated summa cum laude with a B.S.E. in mechanical and aerospace engineering from Princeton University in 2001 after completing a 66-page-long senior thesis, titled "An Investigation of Small-Scale Rotor Blade Aerodynamic Phenomena Using Particle Image Velocimetry and Computational Models", under the supervision of Frederick L. Dryer. [12] [13] Dabiri then returned to Caltech for graduate studies. He was a finalist for both the Rhodes Scholarship and the Marshall Scholarship. He has been awarded NSF research grants eight times in five different fields. [14]

Research

Jellyfish tend to be very efficient when they swim, which means that on a given amount of energy they can go farther than many other animals can. As one of the simplest multicellular organisms, jellyfish (medusae) contract cells to generate jet forces. By mathematically analyzing the fluid vortex rings that form as a result of the contraction, Dabiri was able to model the formation of optimal vortex rings. [15] [16] Moreover, Dabiri and his colleagues experimentally confirmed that such propulsion becomes "a more efficient means of locomotion as animals grow larger", [4] because the relative impact of viscosity on propulsion decreases with greater size. [17]

To further in situ digital particle image velocimetry measurements of propulsion in aquatic animals, Dabiri and his student K. Katija designed and patented a device which very accurately takes measurements that are computed into the kinetic energy due to swimming. [1] [18] Divers use a laser and optics system that illuminates the flow field. The technique allows for refinement and testing of previous models for vortex formation. The research has "profound implications not only for understanding the evolution and biophysics of locomotion in jellyfish and other aquatic animals, but also for a host of distantly related questions and applications in fluid dynamics, from blood flow in the human heart to the design of wind power generators." [4] [19]

The wind energy industry is scaling to larger and larger blades, which harvest more energy. However, Dabiri believes that problems associated with large turbines—design difficulties, building costs, increasing areal needs (turbines are sometimes erected a mile apart to ensure good wind flow), eyesore complaints and accidental bird/bat fatalities—can be avoided through innovation. [20] His FLOWE center, with 24 close vertical axis turbines, is his step towards more economical harvesting of wind energy. [21] Noting that there is constructive interference in the hydrodynamic wakes of schooling fish, Dabiri suggested that extracting energy from flow vortices could aid more than locomotion. [22] His models of the energy extraction mechanism are applicable to the design and evaluation of unsteady aero- and hydrodynamic energy conversion systems, like wind farms. Design of an array of vertical axis turbines led to about an order of magnitude increase in power output per area. [23] Dabiri partnered with Windspire Energy for use of three of 24 turbines that stand approximately 30 feet tall and 4 feet wide. [21] He started a company, Scalable Wind Solutions, to commercialize the software used to optimally place the wind turbines. This has also led to the U.S. Navy funding development of an underwater craft that propels on these concepts, using up to 30% less energy than formerly. [7] [24]

Reverse engineering is Dabiri's newest research focus. In July 2012, a team composed of Caltech and Harvard students and professors published a paper that outlined a tissue engineering method for building a jellyfish out of rat heart muscle cells and a silicon polymer. [25] On a basic level, the function of a jellyfish - using a muscle to pump a fluid - "is similar to that of a human heart, which makes the animal a good biological system to analyze for use in tissue engineering." [26] The next step this research will take is towards a self-sustaining prototype - one that can gather food and activate muscular contractions internally. [27]

Teaching

Dabiri was offered a tenured position at Caltech at the age of 29. [28] He gave the 2010 Convocation Address at Caltech. [29] In 2014, he was appointed the undergraduate Dean at Caltech and he was elected as a Fellow of the American Chemical Society. [30] He was named Professor of the Month at Caltech in February 2012. [31] He served as chair of the faculty board and as dean of students during his 10 years in the Caltech Faculty.[ citation needed ] At the research institute, he has taught several classes, including a graduate class on propulsion, a biomechanics course, a lab class on experimental methods in aeronautics and applied physics, and the introduction fluid mechanics course for which he was highly recommended by students. [31] [32] In 2015 he became a professor at Stanford University. [30]

He is interested in motivating kids considering STEM fields. As recounted in his NPR interview,

Having two parents there who encouraged me and in some cases forced me to study and to really take academics seriously, was very important at an early stage. And then going through school, the role of my teachers was always so important. I remember my fourth grade teacher ... [she] made me believe that I was smart and so I took that and sort of owned that and tried to live up to the expectations that she had placed on me, even as a fourth grader. And so we really want to grab hold of the imagination of the first graders and the second graders at a very early stage, and get them excited about becoming scientists, as excited as they are about becoming a fire fighter or the next rap star. [11]

He is also involved in his church's mentoring program, The Faith Foundation. [11]

Related Research Articles

<span class="mw-page-title-main">Vortex ring</span> Torus-shaped vortex in a fluid

A vortex ring, also called a toroidal vortex, is a torus-shaped vortex in a fluid; that is, a region where the fluid mostly spins around an imaginary axis line that forms a closed loop. The dominant flow in a vortex ring is said to be toroidal, more precisely poloidal.

The vortex tube, also known as the Ranque-Hilsch vortex tube, is a mechanical device that separates a compressed gas into hot and cold streams. The gas emerging from the hot end can reach temperatures of 200 °C (390 °F), and the gas emerging from the cold end can reach −50 °C (−60 °F). It has no moving parts and is considered an environmentally friendly technology because it can work solely on compressed air and does not use Freon. Its efficiency is low, however, counteracting its other environmental advantages.

<span class="mw-page-title-main">Jet propulsion</span> Thrust produced by ejecting a jet of fluid

Jet propulsion is the propulsion of an object in one direction, produced by ejecting a jet of fluid in the opposite direction. By Newton's third law, the moving body is propelled in the opposite direction to the jet. Reaction engines operating on the principle of jet propulsion include the jet engine used for aircraft propulsion, the pump-jet used for marine propulsion, and the rocket engine and plasma thruster used for spacecraft propulsion. Underwater jet propulsion is also used by several marine animals, including cephalopods and salps, with the flying squid even displaying the only known instance of jet-powered aerial flight in the animal kingdom.

<span class="mw-page-title-main">Turbomachinery</span> Machine for exchanging energy with a fluid

Turbomachinery, in mechanical engineering, describes machines that transfer energy between a rotor and a fluid, including both turbines and compressors. While a turbine transfers energy from a fluid to a rotor, a compressor transfers energy from a rotor to a fluid. It is an important application of fluid mechanics.

<span class="mw-page-title-main">Roddam Narasimha</span> Indian scientist (1933–2020)

Roddam Narasimha FRS was an Indian aerospace scientist and fluid dynamicist. He was a professor of Aerospace Engineering at the Indian Institute of Science (1962–1999), director of the National Aerospace Laboratories (1984–1993) and the chairman of the Engineering Mechanics Unit at Jawaharlal Nehru Centre for Advanced Scientific Research. He was the DST Year-of-Science Chair Professor at JNCASR and concurrently held the Pratt & Whitney Chair in Science and Engineering at the University of Hyderabad. Narasimha was awarded the Padma Vibhushan, India's second-highest civilian award, in 2013. for his contributions to advance India's aerospace technology.

<span class="mw-page-title-main">Betz's law</span> Aerodynamic power limitation for wind turbines

In aerodynamics, Betz's law indicates the maximum power that can be extracted from the wind, independent of the design of a wind turbine in open flow. It was published in 1919 by the German physicist Albert Betz. The law is derived from the principles of conservation of mass and momentum of the air stream flowing through an idealized "actuator disk" that extracts energy from the wind stream. According to Betz's law, no wind turbine of any mechanism can capture more than 16/27 (59.3%) of the kinetic energy in wind. The factor 16/27 (0.593) is known as Betz's coefficient. Practical utility-scale wind turbines achieve at peak 75–80% of the Betz limit.

<span class="mw-page-title-main">Gorlov helical turbine</span> Water turbine

The Gorlov helical turbine (GHT) is a water turbine evolved from the Darrieus turbine design by altering it to have helical blades/foils. Water turbines take kinetic energy and translate it into electricity. It was patented in a series of patents from September 19, 1995 to July 3, 2001 and won 2001 ASME Thomas A. Edison. GHT was invented by Alexander M. Gorlov, professor of Northeastern University.

<span class="mw-page-title-main">Windstar turbine</span>

The Windstar vertical-axis turbine is a lift-type device with straight blades attached at each end to a central rotating shaft. Windstar turbines were invented by Robert Nason Thomas and developed by Wind Harvest International, Inc., formerly the Wind Harvest Company, based in Point Reyes, California. Windstar turbines are operated as Linear Array Vortex Turbine Systems (LAVTS). Each rotor unit has a dual braking system of pneumatic disc brakes and blade pitch. All Windstar models use off-the-shelf generators, gearboxes, bearings and other components.

In fluid dynamics, flow can be decomposed into primary flow plus secondary flow, a relatively weaker flow pattern superimposed on the stronger primary flow pattern. The primary flow is often chosen to be an exact solution to simplified or approximated governing equations, such as potential flow around a wing or geostrophic current or wind on the rotating Earth. In that case, the secondary flow usefully spotlights the effects of complicated real-world terms neglected in those approximated equations. For instance, the consequences of viscosity are spotlighted by secondary flow in the viscous boundary layer, resolving the tea leaf paradox. As another example, if the primary flow is taken to be a balanced flow approximation with net force equated to zero, then the secondary circulation helps spotlight acceleration due to the mild imbalance of forces. A smallness assumption about secondary flow also facilitates linearization.

Specialized wind energy software applications aid in the development and operation of wind farms.

<span class="mw-page-title-main">Wind turbine</span> Machine that converts wind energy into electrical energy

A wind turbine is a device that converts the kinetic energy of wind into electrical energy. As of 2020, hundreds of thousands of large turbines, in installations known as wind farms, were generating over 650 gigawatts of power, with 60 GW added each year. Wind turbines are an increasingly important source of intermittent renewable energy, and are used in many countries to lower energy costs and reduce reliance on fossil fuels. One study claimed that, as of 2009, wind had the "lowest relative greenhouse gas emissions, the least water consumption demands and the most favorable social impacts" compared to photovoltaic, hydro, geothermal, coal and gas energy sources.

<span class="mw-page-title-main">Wind-turbine aerodynamics</span> Physical property

The primary application of wind turbines is to generate energy using the wind. Hence, the aerodynamics is a very important aspect of wind turbines. Like most machines, wind turbines come in many different types, all of them based on different energy extraction concepts.

Victor Mikhailovitch Lyatkher (1933) was born in Kerch. He holds a Ph.D. in Engineering Science from the University of Leningrad and a doctorate in science from Moscow State University. Lyatkher is a professor, engineer, and inventor. Lyatkher has developed and patented numerous processes and machines. These deal mainly with renewable energy sources such as tidal power, water turbines, and vertical axis wind turbines. He developed a new method to forecast long-term variations in the Caspian Sea level, and designed a new kind of low head turbine. Mr. Lyatkher has worked for over thirty years in the wind and hydro-power industry. He has received several prizes and awards for his accomplishments, including the Prize of the Council of Ministers of the USSR, the Award of the Indian Society of Earthquake Technology, and five medals of the All Union USSR Exhibition, gold, silver and bronze.

<span class="mw-page-title-main">Cyclorotor</span> Perpendicular axis marine propulsion system

A cyclorotor, cycloidal rotor, cycloidal propeller or cyclogiro, is a fluid propulsion device that converts shaft power into the acceleration of a fluid using a rotating axis perpendicular to the direction of fluid motion. It uses several blades with a spanwise axis parallel to the axis of rotation and perpendicular to the direction of fluid motion. These blades are cyclically pitched twice per revolution to produce force in any direction normal to the axis of rotation. Cyclorotors are used for propulsion, lift, and control on air and water vehicles. An aircraft using cyclorotors as the primary source of lift, propulsion, and control is known as a cyclogyro or cyclocopter. A unique aspect is that it can change the magnitude and direction of thrust without the need of tilting any aircraft structures. The patented application, used on ships with particular actuation mechanisms both mechanical or hydraulic, is named after German company Voith Turbo.

Vortex Bladeless Ltd. is a Spanish technology startup company that is developing a specific type of wind power generator that does not utilize rotating blades or lubricants, which more common wind turbines do use. Power instead is produced from resonant vibrations when wind passes through the turbine and is deflected into vortices in a process called vortex shedding.

Morteza (Mory) Gharib is the Hans W. Liepmann Professor of Aeronautics and Bio-Inspired Engineering at Caltech.

<i>Nemopsis bachei</i> Species of hydrozoan

Nemopsis bachei is a species of relatively small gelatinous zooplankton hydrozoa found in both marine and estuarine environments. This particular species was first found and described by Louis Agassiz in 1849 from samples that were taken from the coast of Massachusetts. It was also noted and described in 1857 by another name off the coast of South Carolina.

<span class="mw-page-title-main">Vertical-axis wind turbine</span> Type of wind turbine

A vertical-axis wind turbine (VAWT) is a type of wind turbine where the main rotor shaft is set transverse to the wind while the main components are located at the base of the turbine. This arrangement allows the generator and gearbox to be located close to the ground, facilitating service and repair. VAWTs do not need to be pointed into the wind, which removes the need for wind-sensing and orientation mechanisms. Major drawbacks for the early designs included the significant torque ripple during each revolution, and the large bending moments on the blades. Later designs addressed the torque ripple by sweeping the blades helically. Savonius vertical-axis wind turbines (VAWT) are not widespread, but their simplicity and better performance in disturbed flow-fields, compared to small horizontal-axis wind turbines (HAWT) make them a good alternative for distributed generation devices in an urban environment.

Homer Joseph "Stewie" Stewart was an American aeronautical engineer, rocket propulsion expert, and Caltech professor, who pioneered the first American satellites.

<span class="mw-page-title-main">Clara O'Farrell</span> American aerospace engineer

Clara O'Farrell is a guidance and control engineer for the Entry, Descent, and Landing (EDL) group at the NASA Jet Propulsion Lab who is known for her work on the Mars Perseverance Rover Mission. Her education and research in aerospace engineering focused in propulsion and fluid dynamics, leading her to work for NASA.

References

  1. 1 2 "Self-contained underwater velocimetry apparatus". Google Patents. Retrieved September 26, 2015.
  2. ↑ Dabiri Lab. John Dabiri. Retrieved 27 September 2019.
  3. 1 2 Biological Propulsion Laboratory Archived 2011-09-03 at the Wayback Machine . See the People page. Retrieved 23 July 2012.
  4. 1 2 3 MacArthur Foundation. John Dabiri. 25 January 2010. Retrieved 23 July 2012.
  5. ↑ Caltech Field Laboratory for Optimized Wind Energy. Includes list of relevant publications. Retrieved 23 July 2012.
  6. 1 2 3 Jellyfish Engineer. Popular Science . Posted 15 October 2008. Retrieved 19 Jan 2018. "Popular Science Homepage". Archived from the original on 8 March 2012. Retrieved 24 July 2012.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
  7. 1 2 John Dabiri Unlocks the Mysteries of Jellyfish. Published 05 April 2012. Retrieved 23 July 2012.
  8. ↑ "President Biden Announces Members of President's Council of Advisors on Science and Technology". whitehouse.gov. 22 September 2021. Retrieved 2022-08-03.
  9. ↑ USA Africa Dialogue. Retrieved 23 July 2012.
  10. ↑ Caltech PR. Retrieved 23 July 2012.
  11. 1 2 3 NPR. California Biophysicist Named MacArthur Fellow. 6 October 2010. Retrieved 23 July 2012.
  12. ↑ Dabiri, John (2001). "An Investigation of Small-Scale Rotor Blade Aerodynamic Phenomena Using Particle Image Velocimetry and Computational Models".{{cite journal}}: Cite journal requires |journal= (help)
  13. ↑ EQuad, Princeton University School of Engineering and Applied Science. See here for honors awarded by the department. Summer 2001. Retrieved 06-08-12.
  14. ↑ curriculum vitae. Retrieved 23 July 2012.
  15. ↑ . Flow patterns generated by oblate medusan jellyfish: field measurements and laboratory analyses. Journal of Experimental Biology. Accepted 31 January 2005. Retrieved 23 July 2012.
  16. ↑ Gharib, M., Dabiri, J.O. The role of optimal vortex formation in biological fluid transport. Proceedings of The Royal Society B. Published online 21 June 2005. Retrieved 23 July 2012.
  17. ↑ Vortex motion in the ocean: In situ visualization of jellyfish swimming and feeding flows. Physics of Fluids. Published 26 August 2005. Retrieved 23 July 2012.
  18. ↑ Self-Contained Underwater Velocimetry Apparatus (SCUVA). Limnology and Oceanography: Methods. 2008. Retrieved 23 July 2012.
  19. ↑ Gharib, M., et al. PNAS. Optimal vortex formation as an index of cardiac health. 27 January 2006. Retrieved 23 July 2012.
  20. ↑ LA Times. Wind turbines growing larger and more powerful. 24 July 2011. Retrieved 23 July 2012.
  21. 1 2 Dabiri challenges the status quo. Archived 2013-05-01 at the Wayback Machine 14 November 2011. Retrieved 23 July 2012.
  22. ↑ Renewable fluid dynamic energy derived from aquatic animal locomotion. Bioinspiration & Biomimetics. IOPScience. Published 10 September 2007. Retrieved 23 July 2012.
  23. ↑ Whittlesey, R.W., Liska, S., Dabiri, J.O. Fish schooling as a basis for vertical axis wind turbine farm design. BIOINSPIRATION & BIOMIMETICS. IOPScience. Published 20 August 2010. Retrieved 23 July 2012.
  24. ↑ Jellyfish engineer. Princeton Alumni Weekly. Published 21 October 2009. Retrieved 23 July 2012.
  25. ↑ Nature Biotechnology. A tissue-engineered jellyfish with biomimetic propulsion. Retrieved 23 July 2012.
  26. ↑ Reverse Engineering a Jellyfish Archived 2013-01-31 at archive.today . Published 23 July 2012. Retrieved 23 July 2012.
  27. ↑ Lab-Made Jellyfish. Updated 22 July 2012. Retrieved 23 July 2012.
  28. ↑ America's Geniuses. Posted 14 October 2010. Retrieved 23 July 2012.
  29. ↑ Caltech Today. 9 September 2010. Retrieved 23 July 2012.
  30. 1 2 "John O. Dabiri's Profile | Stanford Profiles". profiles.stanford.edu. Retrieved 2016-07-08.
  31. 1 2 Prof of the Month. Filed 27 February 2012. Retrieved 23 July 2012.
  32. ↑ Dabiri courses. Caltech ASCIT. Retrieved 23 July 2012.

Notable publications

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