Fundamental Study on the Unsaturated Flow in the Smooth and Rough Walled Small Pipes

Abstract

In recent studies, the importance of preferential flow in mountainous slope have become obvious. To model these phenomena, we should explain the saturated/unsaturated flow in large pores. As the first step to do it, in this paper, based on measurements of water content θ and water flux Q of unsaturated flow in smooth- and rough-walled pipes (8mm dia. and 6.8mm dia.), those phenomena was physically explained and modeled. In smooth pipes, the relation between θ and Q was devided into the three domains, laminar, turbulent and transmission flow. Laminar and turbulent flows were modeled physically. In rough pipes, laminar and turbulent flows appeared, and both were modeled. These flows were explained physically as elemental phenomena in preferential flow.