In Memoriam: Professor Juan C. Lasheras

February 8, 2021

Juan C. Lasheras, University of California San Diego distinguished professor of Mechanical and Aerospace Engineering and Bioengineering, passed away on February 1, 2021 after a brief battle with cancer. He was 69 years old.  

Lasheras was a brilliant scholar, a visionary leader, a supportive mentor, a dedicated educator and a larger-than-life presence in the Department of Mechanical and Aerospace Engineering (MAE) and in the Jacobs School of Engineering. More than that, he was a beloved friend and dear colleague.  

Lasheras was instrumental in founding the Aerospace Engineering program at UC San Diego and in forming the Department of Mechanical and Aerospace Engineering (MAE). In 1999, when the Department of Applied Mechanics and Engineering Sciences (AMES) split into the Department of Mechanical and Aerospace Engineering (MAE) and the Department of Structural Engineering, Juan served as the first Chairman of the new MAE department.  

He was also the founding director of the Center for Medical Devices at UC San Diego, and served as the Interim Dean of Engineering in 2012. Since 2007, he held the Stanford S. and Beverly P. Penner Endowed Chair in Engineering or Applied Sciences.  

Beyond UC San Diego, Lasheras received multiple distinctions and awards. He was a member of the National Academy of Engineering, the National Academy of Inventors, and the Spanish Royal Academy of Engineering. He held honorary doctoral degrees from the Universidad Politécnica de Madrid and from Universidad Carlos III.  

Lasheras was born in Valencia, Spain and spent most of his formative years near Murcia where his father, a mathematician by training, was stationed as a Colonel at the Air Force Academy. At age 18, Lasheras began his studies at the Universidad Politécnica de Madrid in Aeronautical Engineering. However, his academic plans were disrupted at the end of his first year by his father's passing. To provide for his family, he moved back to Murcia and, in the following years, worked as a teacher and director of a preparatory school for air force cadet candidates. During that period, Juan was unable to attend college lectures in Madrid, located 300 miles away, and prepared for course exams using class notes shared by his classmates. Despite these challenges, Juan managed to graduate at the top of his class.  

Upon graduation in 1977, Lasheras secured a Guggenheim fellowship to continue his studies at Princeton University, under the guidance of Professor Irv Glassman, a renowned combustion scientist. It was at Princeton that Lasheras began to develop his skills as a creative experimentalist. He designed a combustion facility from scratch that, for the first time, allowed investigation of the mechanisms for explosive (disruptive) burning of multicomponent and emulsified fuel droplets. His pioneering work caught the attention of the research department at the Shell corporation, which hired him as a Research Scientist in 1981 to direct the combustion group at the Royal Dutch Shell Laboratory in Amsterdam.  

In 1983, Lasheras returned to the US as an Assistant Professor in the Department of Mechanical Engineering at the University of Southern California. In the following years, Lasheras used his experimental skills to investigate a number of fluid dynamics problems related to aerospace propulsion applications. For example, his experiments helped clarify the structure and stability of turbulent mixing layers and jets, as well as the regimes of liquid atomization relevant to the design of rocket engines. It was during his time in Los Angeles that Lasheras met Alexis, whom he married in 1985.  

Already a renowned experimentalist, Lasheras joined UC San Diego as Professor in the AMES Department in 1991. While he maintained an active research program addressing flow problems for engineering applications, he also developed an interest in biomedical applications following the deaths of two of his sisters at an early age. With initial guidance from Professor Shu Chien, Distinguished Professor of Bioengineering and Medicine at UC San Diego, Lasheras was able to build a brilliant career working at the interfaces between mechanics, biology, and medicine in a short time.  

Lasheras' work has led to significant advances in biomechanics. He addressed a wide variety of problems and applications at the macroscopic level, including endovascular techniques to induce and control mild hypothermia, unsteady blood flows and the risk of rupture of aortic and intracranial arterial aneurysms. More recently, his work encompassed cerebrospinal flow in the central nervous system and its role in intrathecal drug delivery procedures. His contributions are equally important at the cellular level, including development of a novel, three-dimensional cell-traction-force microscopy method and clarification of some of the biochemical pathways for the generation of the traction forces exerted by cells during migration. Although his work was driven by a fundamental interest in the underlying physical mechanisms, he always remained a true engineer with an interest in the ultimate applications. He held nearly fifty patents, including one for an endovascular blood-cooling catheter that served as a heat exchanger, the first device approved by the FDA to rapidly cool the body temperature after cardiac arrest to protect the brain from the resulting damage.                                                 

The research style of Lasheras combined an outstanding ability to identify relevant problems in need of further understanding and quantification along with a profound knowledge of the key physical and biological elements involved. Mastering the central physical phenomena and describing them in a clear and concise manner, he was able to design insightful experiments that revealed the underlying phenomena with minimum associated complexity. Although an experimentalist by training, he was interested in complex problems that require an interdisciplinary approach. His success was a result of his remarkable ability to form and motivate research teams that included individuals from different disciplines who were able to contribute a wide range of research tools. Juan's exceptional interpersonal and communication skills were key in enabling and promoting the collaborative work of people with completely different backgrounds, successfully facilitating the harmonious interaction of biologists and medical doctors with electrical, mechanical, and aerospace engineers.  

Lasheras was also an exceptional communicator. He was known for his ability to explain very complex ideas in simple terms. In any given laboratory meeting he could explain the different roles of viscous and pressure forces in blood flow to a doctor, and then turn around and explain the physiology of a red cell to an engineer. These communication skills made him an extremely effective and well-liked teacher. Students gave him the highest recommendations, and he was awarded the Teacher of the Year Award by the MAE department on multiple occasions and by the Engineering Division’s Tau Beta Pi Engineering Honor Society. He was always sought by campus colleagues to serve on Academic Senate faculty committees.  

Lasheras was extremely generous with his time. He somehow seemed to have endless hours available for either serious discussion or friendly conversation, and he handled both with ease. He never turned down a request when his help or advice was needed. For many years, he served as Chairman of the Board of Advisors at Universidad Carlos III in Spain, where he helped organize their Bioengineering program, along with his friend Shu Chien. It has become the leading program in the country.

Lasheras was also very active in service to the scientific community, notably as an Associate Editor of the Journal of Fluid Mechanics and as a participant in activities of the American Physical Society (APS) and the National Institutes of Health (NIH). Besides spending time as Secretary/Treasurer of the Division of Fluid Mechanics of APS and later as Chair of that division, Lasheras was a member of the APS Executive Council. He chaired the Organizing Committee for two annual meetings, having previously received the F. Frenkiel Award for Fluid Dynamics from APS and having been elected an APS Fellow. He was also strongly involved in NIH studies and served as a Permanent Member of the Study Section on Modeling and Analysis of Biological Systems for seven years. Lasheras contributed deep consideration and time to these activities, always trying to make sure that what was done would be best for the scientific community.   

Beyond all of his professional accomplishments and accolades, Lasheras was a caring and generous person. He had a profound impact on many students, staff, and faculty at UC San Diego. This legacy is evident in countless anecdotes they shared including certain impactful career advice, his role in bringing them to UC San Diego, and the help that he graciously offered to them or to their relatives regarding personal challenges.  

Outside of work, he was an excellent golfer and a skilled chef. In his cooking, he applied the same creativity he used in the laboratory, always ready to try new recipes. He and Alexis loved to entertain friends, students, and colleagues and hosted many memorable gatherings in their La Jolla home.  

Lasheras leaves an extraordinary academic legacy, not only in his scientific contributions but also in the innumerable graduate and undergraduate students, postdocs and colleagues that have benefitted from his teaching and mentorship.  

He is survived by Alexis, his wife of over 35 years, his siblings, Maruja, Arsenio, and Teresa, and his nephews and nieces, Javier, Carmen, Jose Maria, Arsenio, Luz, Jaime, and Robbie.


Elizabeth H. Simmons
Executive Vice Chancellor

Albert P. Pisano
Dean, Jacobs School of Engineering 

George Tynan
Professor and Chair, Department of Mechanical and Aerospace Engineering