PERISTALTIC FLOW AND ITS EFFICIENCY

The question of efficiency in performing human and animal biological functions was raised in the context of peristaltic fluid transport. To deal with this problem a complete solution for peristaltic flow in a pipe and in a channel, assuming a given time mean flow, was developed, by a double expansion in terms of the Reynolds number and the square of the wave number. This solution was valid for arbitrary waveshapes. The pressure rise per wave length was constant on a cross section. For a sinusoidal wave (and others) the interaction of Reynolds number and wave number was a 3rd-order effect for this pressure rise. Plow-type waves, nipple-type waves and the sinusoidal wave were compared for maximum efficiency and for minimum energy usage. Large plows were best from mechanical efficiency considerations, but large nipples used the least energy. The biological implications of these results were discussed.