Fundamental Study on the Unsaturated Flow in the Vertical Pipe

Abstract

In order to make clear the physical explanation of the fast flow in macropores or soil-pipes, as a first step, a series of saturated and unsaturated flow experiments were carried out in vertical smooth cylindrical pipes. The objective of this study was to see the relationship between the degree of saturation and the flow rate inside the pipe. The pipes were of the order of mm. The equation for turbulent flow in pipes was modified. The following results were obtained from the experiments conducted:(a) several flow patterns occur depending on the degree of saturation, (b) flow rate for laminar film flow was affected by varying its thickness around the pipewall, and (c) proposed equations for turbulent flow can describe a highly saturated flow approximately.