Modélisation tridimensionnelle des écoulements multiphasiques en régime instationnaire au droit d’ouvrages spéciaux présents en réseau d’assainissement : performances des modèles et analyse de sensibilité

Abstract : With the computational power increasing, CFD modelling is more viable as a design tool or help for site instrumentation in sewers. Moreover, it allows a complete understanding of complex flows often encountered in urban drainage systems. We propose to use the RANS (Reynolds Average Navier-Stokes) approach, implemented in many commercial codes for the simulation of these flows. However, one of the major lacks of these codes is the unreliability of some numerical results, due to the ignorance of uncertainties associated to modelling strategy. This paper aims to quantify these uncertainties and define the range of errors related to numerical results for the largest range of hydraulic conditions and modelling strategies. The expected goal is to extend the use of the RANS approach to practitioners in order to better understand complex hydrodynamics and to be able to improve in situ equipment location and observations. The selected cases for this study are a circular pipe which seems simple to model but with a complex flow pattern and a 90° angle open channel junction. The sensitivity analysis of the model has been investigated by means of pipe flow simulations regarding geometric parameters. First results show that numerical results are sensitive to roughness, even in supercritical conditions. The junction case is used to evaluate the performance of various modelling strategies that we can adopt as well as their impact on simulation results. The wall-law “Scalable” seems to be relevant for this kind of flows.
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Submitted on : Wednesday, January 15, 2014 - 1:47:55 PM
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A. Momplot, G. Lipeme Kouyi, J.-L. Bertrand-Krajewski, Emmanuel Mignot, Nicolas Riviere. Modélisation tridimensionnelle des écoulements multiphasiques en régime instationnaire au droit d’ouvrages spéciaux présents en réseau d’assainissement : performances des modèles et analyse de sensibilité. La Houille Blanche - Revue internationale de l'eau, EDP Sciences, 2013, 2013 (4), pp.16-24. ⟨10.1051/lhb/2013028⟩. ⟨hal-00931486⟩

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