GENERALIZED CULVERT DESIGN DIAGRAM

The features of culvert flow in a basic arrangement ate highlighted. F our fundamental flow types may be identified, namely critical flow, un iform flow, gated dow and pressurized flow. A generalized design diagr am is presented for the circular barrel that gives the possible transi tions between various flow types. Further, the lengths of free surface flows with a central pressurized flow portion are determined as a fun ction of the pipe Froude number. Photographs of model tests illustrate the complex flow patterns that may occur even in a simple culvert arr angement. Of particular relevance are choking conditions and features of two-phase flow in a culvert. The effects of friction coefficient, b ottom slope, relative pipe length, and upstream head are detailed for free culvert outlet conditions.