Author(s): O. Giustolisi; A. Doglioni; D. Laucelli
Linked Author(s):
Keywords: Corrugated pipe; Wake-interference flow; Resistance coefficient; Genetic Programming (GP)
Abstract: Experimental results of tests on three full-circular corrugated plastic pipes are reported and discussed. Tests were performed measuring open-channel flow hydraulic parameters for the slopes, from 0.00698 to 0.1737, but actually it has been observed that wake-interference flow occurs from 0.0349 to 0.1737 (2 to 10 degrees). In wake-interference flow, Weisbach's resistance coefficient increases with increasing the Reynolds number in the region of the Moody-type diagram, which normally characterises fully developed turbulent flow, because of the macro-roughness elements at wall. These generate eddies interfering with each other. For this reason, the Moody-type diagram, related to Nikuradse-type dense random surface roughness, does not predict at all Weisbach resistance coefficient. From a technical viewpoint, wake-interference flow is interesting because of the abnormal turbulence along the channel wall-roughness elements that generates additional dissipations. This phenomenon could be useful in sewer networks installed on sloping soils. Therefore, this work presents some formulas for Weisbach and Chezy resistance coefficients in corrugated channels. The best of these formulas has been obtained by means of Genetic Programming strategy to perform knowledge based on data.
Year: 2003