National Water Center, Eureka Springs, Arkansas
National Water Center, Eureka Springs, AR
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Flowforms, Fluid Flows, The Fluent Heart
by Philip Kilner
(See Full article, movies and animations at the following website:)
http://www.flowforms.com
(Double-click on thumbnail prints above to view larger print.)
The pictures above show variants of the Flowform principle, discovered and described by A John Wilkes.
Cavities are shaped to accommodate spontaneous cycles of wave propagation over streams that enter continuously, but re-circulate asymmetrically and rhythmically. This oscillation may be seen as a liquid counterpart of compression-wave oscillation in wind instruments such as whistles and flutes. John Wilkes' initial discovery was of the dual-cavity type (upper row, left and center) with symmetrically paired cavities in which flow oscillates from side to side. The single, asymmetric cavity variant, which converts continuous inflow to intermittent outflow (lower row, and upper row, right) was devised by Philip Kilner (writing this), while studying with John Wilkes - a discovery that led on to studies of flow through the heart.
The flow sculpture, top right, was made in copper by Philip Kilner and is at Royal Brompton Hospital in London.
There may be relationships between the spontaneous, asymmetric flow cycles in cavities of Flowforms, on the one hand, and the cycles of flow through cavities of the heart, on the other. Blood flow cycles, however, are dominated by contraction of heart muscle, initiated by cells of the 'pacemaker' region, whereas cycles in Flowforms arise through cyclic propagation of surface waves, deriving their energy from the inflowing stream. Cyclic redirection the momentum of inflowing blood, with passive displacement of relaxed, compliant cavity walls, must, however, be an aspect of heart rhythm, obscured by the dominance of myocardial contraction. The functional role of this passive interaction, which may prime muscle fibers for subsequent contraction, could be at artrial rather than ventricular level, and more on exercise than at rest. Blood entering from veins takes a finite time to flow in, turn and exit - a period that may be coupled to myocardial compliance and contraction. It is on exertion that dynamics of blood momentum-change, of vascular and myocardial elasticity, and of myocardial contraction are likely come into vigorous, tightly coupled interaction.
Asymmetric flow oscillators illustrated above also raise a question about evolutionary
origins of the looped, ventrally located heart found in the vertebrates. It seems likely that the ventral heart emerged in a pre-existing circulatory system, through which blood may have been moved by compression or contraction of more widely distributed vessel segments. Could passive or partly passive oscillatory cycles have played a part in establishment of a sinuous vessel region as the favored location for what evolved to become the looped curvatures of the vertebrate heart?
(Please see heart in motion at this web site.) www.flowforms.com
Compare forms of a small water trickle oscillator, flowing downwards and leftwards, with those of (even smaller) chick embryo hearts, which in the drawings below would be flowing up the screen:
Sources
Magnetic resonance images and streamline maps on this site are from the Cardiovascular Magnetic Resonance Unit at the Royal Brompton Hospital site of Imperial College of Medicine, Science and Technology, London, UK. We are grateful for the collaboration of all our colleagues in this Unit, and in the departments of Cardiology and Cardiothoracic Surgery, and Computing.
We are grateful for financial support from The British Heart Foundation and CORDA charities, and for funding of computing equipment by a HEFCE JREI award.
Guang-Zhong Yang developed MRI flow visualization technique used for the Nature publication and the animations for this web site (reference #5). It is his heart that features in the MRI flow images on this site.
Photographs of pulmonary arterial and venous trees are from resin casts that were prepared for the Brompton Hospital several decades ago.
The text of the website, the drawings of the heart, and the models of embryos are by Philip Kilner, as are the flow grateful acknowledgement to John Wilkes.
John Wilkes is a sculptor, water expert and originator of the Flowform Methods. His work, based at Emerson College in Sussex, UK, combines artistic and scientific approaches to water and organic form, owing much to insights of the following artist-scientists:
Theodor Schwenk was a fluid engineer, photographer, founder of the Institut fur Stromunswissenschaft at Hereschried, Germany, and author of 'das sensible Chaos' (published in 1962 by Verlag vries Geistesleben, Stuttgart, translated as 'Sensitive Chaos', 1996, Anthroposophic Press, New York).
Rudolf Steiner (1861-1925) edited Goethe's scientific writings and founded Anthroposophy - a path of knowledge and development of humanity which embraces philosophical, religious, artistic and scientific approaches.
Johann Wolfgang von Goethe (1749-1832) is widely regarded as the greatest German poet and playwright. He is less well known as a natural scientist of outstanding breadth and perceptiveness.
Philip Kilner, p.kilner@rbh.nthames.nhs.uk Asymmetric redirection of flow through the heart Philip J Kilner *, Guang-Zhong Yang*^2, A John Wilkes ^n, Raad H
Mohiaddin*, David N
Firmin*, Magdi H Yacoub
*Cardiovascular Magnetic Resonance Unit, ^2 Visual Information, Processing Group of Department of Computing and Department of Cardiothoracic Surgery, Royal Brompton Hospital site of Imperial College of Science, Medicine and Technology, Sydney Street, London SW3 6NP, UK.
Flow Design Research Group, Emerson College, Forest Row, East Sussex RH18 5JX, UK
This paper was published in the journal Nature, published by Macmillan, London (Nature, April 13th, 2000, Volume 404, 759-761).
