Leonardian fluid mechanics

More information: Roberto Revelli




As evidenced by many scholars, hydraulics was one of the main interests of Leonardo da Vinci. His manuscripts are full of notes, meditations, drawings and projects on water, covering a large number of subjects from hydrostatics to river hydraulics, from transport phenomena to the design of hydraulic machines, structures and facilities. Presenting himself to Ludovico il Moro, moreover, Leonardo declares that he is able to invent and realize these kinds of works better than anyone else. On what bases can Leonardo state such an affirmation of superiority? 

Leonardo's expertise, first of all, surely comes from the well-established technical tradition of his time. But his ability to improve this tradition, probably, also results from the particular approach that he adopts to solve the problems encountered in his activity as an engineer. 

This approach, that today we recognize as similar to the method of a research engineer, is effectively resumed by Hunter Rouse in his volume “Engineering Hydraulics”: “Practically every problem in engineering hydraulics involves the prediction by either analytical or experimental methods of one or more characteristics of flow. There are, in brief, three different bases for such prediction. The first is that of "engineering experience" gained in the field by each individual engineer. The second is the laboratory method of studying each specific problem by means of scale models. The third is the process of theoretical analysis. The most effective solution of almost any problem will be obtained by combining the best features of all three methods of approach.” 

An example of this kind of method is given by Leonardo's personal experiences, laboratory studies and theoretical analyses on hydrostatics and especially on pressure and buoyancy, together with their applications to the problems of navigation or the construction of canals, banks, reservoirs and scales.

Leonardo da Vinci
Codex Madrid I, f. 145 verso
Studies on buoyancy



Laboratory reproduction of an experiment by Leonardo described in Codex Atlanticus, f. 219 recto: "Per vedere quale acqua del vaso è quella che si muove all'uscita del fondo d'esso vaso, piglierai due piastre di vetro quadre d'un quarto di braccio, e falle vicine l'una all'altra 2 coste di coltello con uniforme spazio, e salda li stremi da 3 lati colla cera. Poi pel quarto lato l'empi d'acqua chiara nella quale sia sparso piccole semenze le quali sien notanti per tutta l'altezza di tale acqua. Di poi farai un piccolo buso nel fondo e dà l'uscita a tale acqua e tieni l'occhio fermo nella faccia del vase e 'l moto delle dette simenze ti darà notizia quale è quell'acqua che con più velocità corre all'uscita e di qual sito si move."