Maths and physics for anaesthetists : laminar and turbulent flow.

London : University of London Audio-Visual Centre, 1976.

1 encoded moving image (28.29 min.) : sound, black and white

00:28:29

University of London

Unrestricted

CC-BY-NC

Creative Commons Attribution-Non-Commercial 2.0 UK: England & Wales

In English

Presented by DW Hill, Reader in Medical Physics. Produced by David R Clark and Michael Tomlinson. Film extract provided by courtesy of Dr JT Wright, Bio-engineering and Medical Physics Unit, University of Liverpool. Made for British Postgraduate Medical Federation. Made by University of London, Audio-Visual Centre.

This video is one of around 310 titles, originally broadcast on Channel 7 of the ILEA closed-circuit television network, given to Wellcome Trust from the University of London Audio-Visual Centre shortly after it closed in the late 1980s. Although some of these programmes might now seem rather out-dated, they probably represent the largest and most diversified body of medical video produced in any British university at this time, and give a comprehensive and fascinating view of the state of medical and surgical research and practice in the 1970s and 1980s, thus constituting a contemporary medical-historical archive of great interest. The lectures mostly take place in a small and intimate studio setting and are often face-to-face. The lecturers use a wide variety of resources to illustrate their points, including film clips, slides, graphs, animated diagrams, charts and tables as well as 3-dimensional models and display boards with movable pieces. Some of the lecturers are telegenic while some are clearly less comfortable about being recorded; all are experts in their field and show great enthusiasm to share both the latest research and the historical context of their specialist areas.

Segment 1 Hill talks to camera and introduces the subject. He shows a film which visualises blood flow through a heart valve, he points out how complicated the flow patterns are, and in particular the areas of turbulent flow. A further film is shown which compares fluid and electrical flow patterns, then the flow patterns of different types of liquid. Time start: 00:00:00:00 Time end: 00:04:54:00 Length: 00:04:54:00

Segment 2 Hill shows an animated model demonstrating flow patterns through a series of layers of molecules, as might happen in a blood vessel. To explain this further, he then shows an animated model looking at how a fluid flows down a pipe - he describes the various patterns of flow in depth. Hill then introduces the concept of Newton's law of viscous flow and applies it to his animated model. He points out that Newton's law applies only to laminar or streamline flow with a fluid of constant viscosity. Next Hill talks about the Hagen-Poiseuille equation which helps to calculate volume flow rates down tubes - Hill applies this to a variety of endotracheal tubes used in surgery. Time start: 00:04:54:00 Time end: 00:11:20:00 Length: 00:06:26:00

Segment 3 We are shown a film of a pneumotachograph, a device for measuring the volume flow rage of gasses; these are widely used in respiratory and lung function studies. Hill shows an animated model of the progression of different velocity molecules down a pipe, then refers to graphs comparing turbulent and laminar flow. Time start: 00:11:20:00 Time end: 00:16:26:00 Length: 00:05:06:00

Segment 4 Hill shows 5 pairs of illustrations showing different flow patterns taken from water flowing through a 2cm long glass tube with dye injected halfway along. He describes how the different rates of dye injection (either continuous or sporadic at varying intervals) show up the different patterns of flow rate. He then applies these to the practice of anaesthesia, for instance, by looking at how areas of athersclerosis in an artery can change the patterns of blood flow. Time start: 00:16:26:00 Time end: 00:20:14:00 Length: 00:03:48:00

Segment 5 Hill describes how blood, which is of non-Newtonian viscosity, must be understood differently in order to help patients, particularly those in intensive care where the balance between blood flow and blood viscosity must be carefully achieved. A short film showing the viscosity of Dulux gloss paint is shown to demonstrate how working it with a brush can change it from barely fluid to relatively flowing. Time start: 00:20:14:00 Time end: 00:25:52:15 Length: 00:05:38:15

Segment 6 Hill summarises the lecture, referring back to earlier films, graphs and diagrams. He describes again the streamline flow pattern, the Hagen-Poiseuille equation and Newton's law of viscosity. Finally he provides a list of publications for further study into the subject. Time start: 00:25:52:15 Time end: 00:28:29:02 Length: 00:02:36:12