Leonardo's Heart Valve

Leonardo's studies of cardiovascular systems in more than 50 surviving pages from 2 phases of his research (around 1508—1509 to 1513), are a clear demonstration of his observational genius and progressive deduction of cardiac mechanics and the vascular system.

He carried out a detailed hemodynamic study of the aortic valve motion and the role of sinus Valsalva in the closure dynamics of the aortic valve, and he accurately correlated the formation of vortices with the separation of a retarded (shear) layer from the lips of the leaflets. In-vivo verification of vortex formation in the sinus of Valsalva during the systolic phase awaited the application of modern phase-averaged magnetic resonance imaging techniques. Did Leonardo actually build the glass model he twice mentioned, thus performing the first scientific flow visualization of impulsive vortex formation or other fluid mechanical phenomena? Evidence in support of this possibility can be found in both the unusually schematic style he employed for the suite of drawings and the recent flow imaging results obtained in our laboratory through laser based imaging technique.

A replica of the heart valve designed by Leonardo da Vinci was created by Professor Gharib, Dr. Arash Kheradvar (MD), Mr. Richard P. Gerhart (Caltech Glass shop), and Mr. David Kremers and became part of the exhibit, Leonardo Da Vinci: Experience, Experiment, and Design, at the
Victoria and Albert Museum in London (14 September 2006 - 7 January 2007). Click here for the press release (pdf) announcing the exhibit.

Publication
Gharib M, Kremers D, Koochesfahani MM, et al., Leonardo's vision of flow visualization, EXP FLUIDS 33 (1): 219-223 JUL 2002

Photo Album

 

Studies of Two-Dimensional Flows Using Soap Films

The importance of theoretical and experimental studies of two-dimensional flows is long-standing and well-known. These studies have significant implications on two-dimensional turbulence, transition mechanisms in shear flows, and the fundamentals of two-dimensional vortex dynamics relevant to oceanic and atmospheric problems. The experimental verification of the numerous models and theories that have been evolved in the past decades is difficult if not impossible to do by conventional experiments. We have invented a continuously running Soap-Film Tunnel that realistically simulates two-dimensional flows. We have used laser Doppler velocimetry to study two-dimensional turbulence and wakes of various two-dimensional objects. Since the speed of sound is only 6 m/s in the film, it is possible to simulate high subsonic jets in the soap-film tunnel.

The above award-winning photograph [Album of Visualization (1995, 1996), The Visualization Society of Japan, 12, 1-2; 13, cover] shows flow visualization of a two-dimensional co-jet in a soap-film tunnel. The film is 5µ thick and has velocity of 6 cm/s at the jet exit. The film is visualized by the interference effect.

(Below) See an animation of pulses of air moved by a diaphragm of a sound speaker, touching down upon a soap film stretched on a frame. Click here or on image below to view the animation.

Created by Alma Gharib and Caltech conceptual artist, David Kremers, in 2001.