Flow of Liquids in the Critical Region

Abstract

IN experiments on the flow of water in a long copper tubing, it was found that the inlet pressure must be maintained free from disturbances to the highest degree possible if flow in the critical region is to be analysed. When extraneous disturbances were eliminated, the flow in the tube falling between Reynolds' numbers 1,000 and 5,000 was found to fall into three distinct classes, all of which were different from both the viscous and the turbulent regimes. Strictly speaking, only the regime existing between 2,200 and 2,500 Reynolds' numbers in the present system showed the ordinarily accepted criteria of critical flow. Nevertheless, as both the regions between 1,000 and 2,200 and between 2,500 and 5,000 fall outside the laws of either viscous or turbulent regimes, they are treated here as 'pre-critical' and 'post-critical' regimes.