Experiments on the flow of viscous fluids through orifices

Abstract

This paper deals with an experimental investigation of the flow of liquids through a round hole. In most of the experiments a fairly thick oil was used, and by varying its temperature the kinematic viscosity could be varied about a thousand-fold. It was possible by this means to change the character of the motion continuously from the type determined almost wholly by viscosity to the form in which the resistance was mainly due to inertia, and to follow the corresponding change in the relation of resistance and flow. When the experiments were first undertaken it was hoped by comparing experiments with orifices of different sizes, and in which the viscosity and rate of flow were suitably varied, to obtain con­firmation of the law of similar motion in viscous fluids. It was found, however, that this law did not hold, and the cause was discovered to be that the stress in this oil is not proportional to the rate of distortion.