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Simulation du comportement d'ellipsoïdes en écoulement turbulent confiné

Abstract : Using direct numerical simulation (DNS), the dynamics of inertial, non-spherical particles carried by the turbulent flow in a channel has been studied numerically. Under the hypothesis of pointwise particles, modelled as prolate ellipsoids, Lagrangian particles tracking is used to study the influence of the particle aspect ratio and inertia on their interaction with the flow. Direct numerical simulation of the flow allows to obtain an accurate information about the properties of the fluid at the particle position, which are required to compute the hydrodynamic actions that they undergo. The hydrodynamic actions have been computed using two different methods to study the influence of their modelling on the particle dynamics. The first model is based on theoretical formulas which are valid under the assumption that there is a creeping flow motion at the particle scale and are widely used in the literature. The second model relies on correlations, which are valid at moderate values of the particle Reynolds number. Simulations have been carried until the particle distribution reaches a steady state in order to obtain an unbiased comparison of the influence the particle shape and inertia. For both modelling of the hydrodynamic actions, translation velocity statistics do not significantly depend on the particle shape. There are however important quantitative differences between the translation statistics obtained using each model. Angular velocity statistics are strongly influenced by the hydrodynamic actions modelling, everywhere in the channel. These observations about the influence of the modelling remain valid for higher values of the flow Reynolds number. Increasing the value of this parameter nonetheless causes an uniformization of the particle distribution and increases the magnitude of the fluctuations of the velocity and angular velocity of the fluid seen by the particles. These stronger fluctuations modify the preferential orientation of the ellipsoids, regardless of their characteristics and of the model used to compute the hydrodynamic actions. The comparison of the simulation results with experimental data indicates that the model valid under the creeping flow assumption allows to simulate the dynamics of very long and weakly inertial ellipsoids realistically.
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Submitted on : Wednesday, April 6, 2022 - 2:20:18 PM
Last modification on : Thursday, April 7, 2022 - 3:34:04 AM

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  • HAL Id : tel-03632673, version 1

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Antoine Michel. Simulation du comportement d'ellipsoïdes en écoulement turbulent confiné. Dynamique des Fluides [physics.flu-dyn]. Université de Lorraine, 2021. Français. ⟨NNT : 2021LORR0188⟩. ⟨tel-03632673⟩

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