Design of a Pressurized Rectangular Conduit With Triangular Bottom Using The Rough Model Method

Abstract

A new theory is presented to design pressurized conduits, particularly rectangular shaped conduit with triangular bottom. This theory is based on a referential rough conduit model characterized by an arbitrarily assigned relative roughness taken in the rough turbulent flow regime. Thus, the geometric elements of the chosen model are well defined. In particular, the relative height of the rough model, which is expressed by an implicit relationship, has been resolved by an appropriate limited development. The obtained relationship is used to calculate the almost exact value of the relative height of the model depending solely on the given side slope. The absolute height of the rough model is given by an explicit relationship based on measurable data in practice, such as side slope, discharge and energy slope. The required linear dimensions of the conduit are obtained by multiplying the homologues linear dimensions of the rough model by a non-dimensional correction factor which depends on the known rough model characteristics. Practical examples are presented to explain the procedure of calculation and to better understand the advocated method.