Transition between laminar and turbulent flow in human trachea

¹ Department of Cardiology and Clinical Physiology; and Department for Psychosomatic Research, Wilhelmina Gasthuis, Amsterdam, The Netherlands

The critical velocities at which turbulence appears were determined, during the flow of both water and air, in 21 transparent plastic casts of human tracheae. The flow patterns varied considerably in casts from different individuals. The critical flow velocity of air moving through tracheal casts without the larynx averaged about 350 ml of air per second. In tracheal casts including the larynx, with the glottis in cadaveric position, the critical inspiratory flow was about 50 ml of air per second. With the glottis opened into a more natural position, the critical inspiratory flow velocity was higher, about 100 ml of air per second. The mean value of the critical expiratory flow was 122 ml of air per second. Air flow in the trachea of most individuals is probably turbulent during the greater part of normal respiratory activity. Calculation of critical flow velocities in the airways by means of Reynolds' formula for smooth cylindrical tubes leads to erroneously high values.

This article has been cited by other articles:

				C. Darquenne, M. Paiva, and G. K. Prisk Effect of gravity on aerosol dispersion and deposition in the human lung after periods of breath holding J Appl Physiol, November 1, 2000; 89(5): 1787 - 1792. [Abstract] [Full Text] [PDF]