The semicircular open conduit that used in practice in sanitary sewers, water supply lines and storm drain, is characterized by the linear dimension, radius and the normal depth, the problem consists in evaluating the linear dimension, for know value of discharge passé through pipe, the energy slope, absolute roughness characterizing the state of the internal wall of the conduit and the kinematic viscosity of the liquid. Design a conduit requires the use of iterations or graphic methods due to the implicit form of the equations forming the basic system of the turbulent flow. We compute the radius of the conduit by using steps of calculations; the equations founded are direct and explicit.
Keywords: uniform flow, turbulent flow, explicit solution, semicircular section, discharge
* Preliminary version