Discussion of “Modified Hazen–Williams and Darcy–Weisbach Equations for Friction and Local Head Losses along Irrigation Laterals” by John D. Valiantzas

LES of the flow around two cylinders in tandem

The flow around an arrangement of two-in-tandem cylinders exhibits a remarkably\ud complex behaviour that is of interest for many engineering problems, such as environmental\ud flows or structural design. In the present paper, a Large Eddy Simulation using a staggered\ud Cartesian grid has been performed for the flow around two-in-tandem cylinders of diameter\ud D=20mm and height H=50mm submerged in an open channel with height h=60 mm. The two\ud axes have a streamwise spacing of 2D. The Reynolds number is 1500, based on the cylinder\ud diameter and the free-stream velocity u�. The results obtained show that no vortex shedding\ud occurs in the gap between the two cylinders where the separat…

Integrated emitter local loss prediction using artificial neural networks.

This paper describes an application of artificial neural networks (ANNs) to the prediction of local losses from integrated emitters. First, the optimum input-output combination was determined. Then, the mapping capability of ANNs and regression models was compared. Afterwards, a five-input ANN model, which considers pipe and emitter internal diameter, emitter length, emitter spacing, and pipe discharge, was used to develop a local losses predicting tool which was obtained from different training strategies while taking into account a completely independent test set. Finally, a performance index was evaluated for the test emitter models studied. Emitter data with low reliability were removed…

Three-Dimensional Modeling and Geometrical Influence on the Hydraulic Performance of a Control Valve

The ability to understand and manage the performance of hydraulic control valves is important in many automatic and manual industrial processes. The use of computational fluid dynamics (CFD) aids in the design of such valves by inexpensively providing insight into flow patterns, potential noise sources, and cavitation. Applications of CFD to study the performance of complex three-dimensional (3D) valves, such as poppet, spool, and butterfly valves, are becoming more common. Still, validation and accuracy remain an issue. The Reynolds-averaged Navier–Stokes equations were solved numerically using the commercial CFD package FLUENT V6.2 to assess the effect of geometry on the performance of a …

Survey data on the consequences of COVID-19 and home confinement on the educational community and families in Spain

[EN] This paper presents a dataset concerning the consequences of the COVID-19 pandemic and home confinement on the educational community and families, and the possibilities and opportunities for the return to schools. Data were collected through an online based cross-sectional survey between June 29, 2020 and July 12, 2020 in Spain. A total of 7,305 people who had children in their care during the COVID-19 crisis and the home-confinement period responded to the survey. The survey contained items concerning (i) socio-demographic information, (ii) conciliation of work, personal and family life during confinement, (iii) the impact of the pandemic on the respondent's family, and (iv) the respo…