Numerical analysis of hydraulic jumps using OpenFOAM

[EN] The present paper deals with a hydraulic jump study, characterization and numerical modeling. Hydraulic jumps constitute a common phenomenon in the hydraulics of open channels that increases the shear stress on streambeds, so promoting their erosion. A three-dimensional computational fluid dynamics model is proposed to analyze hydraulic jumps in horizontal smooth rectangular prismatic open-air channels (i.e., the so-called classical hydraulic jump). Turbulence is modeled using three widely used Reynolds-averaged Navier Stokes (RANS) models, namely: Standard k ε, RNG k ε, and SST k ω. The coexistence of two fluids and the definition of an interface between them are treated using a volume method in Cartesian grids of several element sizes. An innovative way to deal with the outlet boundary condition that allows the size of the simulated domain to be reduced is presented. A case study is conducted for validation purposes (FR1 ∼ 6.10, Re1 ∼ 3.5·105): several variables of interest are computed (sequent depths, efficiency, roller length, free surface profile, etc.) and compared to previous studies, achieving accuracies above 98% in all cases. In the light of the results, the model can be applied to real-life cases of design of hydraulic structures.This research was conducted thanks to the funding provided by the VALi + D R&D Program of the Generalitat Valenciana (Spain). It would not have been possible without the contribution of Daniel Valero and Beatriz Nacher of the Hydraulics Laboratory of the School of Civil Engineering (Universitat Politecnica de Valencia).Bayón Barrachina, A.; López Jiménez, PA. (2015). Numerical analysis of hydraulic jumps using OpenFOAM. Journal of Hydroinformatics. 17(4):662-678. https://doi.org/10.2166/hydro.2015.041S66267817

In Vitro Proliferation of Three Iranian Apricot Varieties by Single Node Culturing

In vitro propagation of three Iranian apricot cultivars, “Ghavami”, “RajabAli” and “Khiveei” was studied by direct micropropagation technique. To optimize sterile manipulation, shoot nods of one year-old dormant vegetative shoots and current growing vegetative shoot were cultured in WPM medium after treatment by HgCl2, citric acid, ethanol and NaClO (10, 15, 20 min). Establishment of buds was tested in the MS and WPM mediums. Proliferation of sprouting buds was evaluated in WPM medium supplemented with three concentrations of (0.5, 1 and 2 mg/l) BAP and 0.05 mg/l of IBA. A half-Strength MS medium supplemented with three concentrations (0.5, 1 and 2 mg/l) of IBA was used as a rooting medium. The greatest number of contamination-free shoots in HgCl2 0.01% and citric acid 0.07% treatments were obtained. No significant difference was found between two different mediums in terms of bud vegetative growth. The shoot number and length were significantly affected by apricot varieties and BAP concentrations. The greatest numbers of proliferated shoot were observed in Rajabali and Ghavami varieties at 1 mg/l of BAP, whereas maximum number of shoot in Khiveei cultivar was observed in 0.5 mg/l of BAP. The maximum shoot length in Rajabali and Ghavami cultivars was obtained in 2 mg/l of BAP

The surface gradient method for the treatment of source terms in the shallow-water equations

A novel scheme has been developed for data reconstruction within a Godunov-type method for solving the shallow-water equations with source terms. In contrast to conventional data reconstruction methods based on conservative variables, the water surface level is chosen as the basis for data reconstruction. This provides accurate values of the conservative variables at cell interfaces so that the fluxes can be accurately calculated with a Riemann solver. The main advantages are: (1) a simple centered discretization is used for the source terms; (2) the scheme is no more complicated than the conventional method for the homogeneous terms; (3) small perturbations in the water surface elevation can be accurately predicted; and (4) the method is generally suitable for both steady and unsteady shallow-water problems. The accuracy of the scheme has been verified by recourse to both steady and unsteady flow problems. Excellent agreement has been obtained between the numerical predictions and analytical solutions. The results indicate that the new scheme is accurate, simple, efficient, and robust