This paper is devoted to the validation of a two-fluid two-phase flow model in some highly unsteady situations involving strong rarefaction waves and shocks in water-vapor flows. The two-fluid model and its associated numerical method that were introduced in a previous work are first recalled, and details on the computational scheme and the verification of interfacial mass transfer terms are provided. Consistency with experimental data is checked in three configurations. First, a comparison with the speed of sound in a two-phase mixture is detailed. Afterwards, numerical approximations obtained with the two-fluid approach are discussed and compared with some experimental data documented in the Simpson water-hammer experiment and the high depressurization with flashing associated with Canon experiment.

This paper is devoted to the validation of a two-fluid two-phase flow model in some highly unsteady situations involving strong rarefaction waves and shocks in water-vapour flows. The two-fluid model and its associated numerical method that were introduced in a previous work are first recalled, and details on the computational scheme and the verification of interfacial mass transfer terms are provided. Consistency with experimental data is checked in three configurations. First, a comparison with the speed of sound in a two-phase mixture is detailed. Afterwards, numerical approximations obtained with the two-fluid approach are discussed and compared with some experimental data documented in the Simpson water-hammer experiment and the high depressurization with flashing associated with Canon experiment.

We present in this paper some comparisons of numerical results and experimental data in some two-phase flows involving rather high pressure ratios. A two-fluid two-phase flow model has been used herein, but we also report a few results obtained with some simpler single-fluid two-phase flow models.

We examine in this paper the accuracy of some approximations of the Baer-Nunziato two-phase flow model. The governing equations and their main properties are recalled, and two distinct numerical schemes are investigated, including a classical second-order extension relying on symmetrizing variables. Shock tube cases are considered, and two simple Riemann problems based on well-balanced initial data are detailed. These enable to recover the expected convergence rates. However, it is shown that these simple cases are indeed very difficult and that the accuracy of basic schemes is rather poor.

Cette thèse contribue à la vérification et à la validation du modèle bi-fluide de Baer-Nunziato, pour modéliser les phénomènes de transitoires hydrauliques dans les réseaux de tuyauteries industrielles. Il s’agit d’abord de modéliser les écoulements de transitoires hydrauliques avec le modèle bi-fluide en représentation eulérienne, puis d’étendre ce modèle en formalisme ALE (Arbitrary Lagrangian Eulerian) pour prendre en compte l’interaction fluide-structure (IFS). Pour modéliser les écoulements, des lois de fermetures du modèle bi-fluide concernant les termes interfaciaux, les termes sources et les lois thermodynamiques (EOS) ont d’abord été étudiées. Ensuite, le système complet a été simulé avec une méthode à pas fractionnaires qui admet deux étapes, l’une pour la résolution de la partie convective, l’autre pour les termes sources. L’ensemble de schémas a été vérifié et étendu aux EOS ‘Stiffened Gas généralisées’ afin de représenter le changement de phase eau-vapeur. Après avoir retrouvé certains phénomènes typiques associés aux transitoires hydrauliques, le modèle bi-fluide a été validé avec l’expérience de Simpson, l’expérience Canon, et comparé avec deux modèles homogènes sur ces deux expériences. Enfin, une version ALE du modèle bi-fluide a été mise en œuvre et vérifiée sur un cas de propagation d’ondes de pression dans une conduite flexible. La variation de la célérité des ondes dans le fluide liée au couplage fluide/structure a été bien retrouvée. La validation a été effectuée sur un cas expérimental d'explosion dans une tuyauterie en eau. Les simulations sont en bon accord avec les données expérimentales

This paper is devoted to the computation of the Baer-Nunziato model, and more precisely to the verification of a few schemes, while using analytic solutions of the onedimensional Riemann problem.Since classical perfect gas EOS may imply specific behaviours, we wish to investigate any kind of EOS, and thus we focus on and verify capabilities and drawbacks of simple enough solvers such as the Rusanov scheme.For so-called first-order (respectively second-order) Finite-Volume schemes, we check that a h 1/2 (resp.h 2/3 ) rate of convergence is retrieved.Actually, the fractional step approach is also shown to be more stable than the single-step approach.