Bulletin of the American Physical Society
68th Annual Meeting of the APS Division of Fluid Dynamics
Volume 60, Number 21
Sunday–Tuesday, November 22–24, 2015; Boston, Massachusetts
Session E9: CFD: Computational Methods and Modeling of Multiphase Flows II |
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Chair: Mathieu Lepilliez, University of Toulouse Room: 109 |
Sunday, November 22, 2015 4:50PM - 5:03PM |
E9.00001: Detailed modeling of sloshing in satellites tank at low Bond numbers Mathieu Lepilliez, Sebastien Tanguy Consumption of ergols is a critical issue regarding the whole lifetime of a satellite. During maneuvers in mission phases, the Helium bubble used to pressurize the tank can move freely inside, thus generating movement of the center of mass, and sloshing which can disrupt the control of the satellite. In this study we present numerical results obtained from CFD computation, using an Immersed Interface Method to model the tank with a level-set approach for both liquid-gas interface and solid-fluid interface. A parametric study is proposed to observe the influence of the Bond number on resulting forces and torques generated on the tank. One can observe different steps during the maneuvers under microgravity: the first part is dominated by accelerations and volume forces, which flatten the bubble on the hydrophilic tank wall. When the forcing stops, the bubble bounces back, generating sloshing by moving under the influence of inertia and capillary effects. Finally viscous effects damp the sloshing by dissipating the kinetic energy of the bubble. Those results are compared to actual in-flight data for different typical maneuvers on forces and torques, allowing us to characterize the period and damping of the sloshing. [Preview Abstract] |
Sunday, November 22, 2015 5:03PM - 5:16PM |
E9.00002: Structures in the Oscillatory regime of RLDCC flow Nagangudy Panchapakesan Rotating lid driven cubical cavity flow (RLDCC flow) is studied with a view to test structure eduction algorithms. OpenFoam software was used to simulate the RLDCC flow at Reynolds numbers higher than the critical Reynolds number for this geometry. Vortex bubble and other characteristic structures were observed in these simulations. The vector fields of the simulations were further analyzed with LCS and other methodologies to educe the structures. The structures were compared with level sets of different dynamical variables. The ability of these algorithms to present a coherent representation of the time evolution and unsteady dynamics of the bubble and other structures is evaluated. [Preview Abstract] |
Sunday, November 22, 2015 5:16PM - 5:29PM |
E9.00003: Aref's chaotic orbits tracked by a general ellipsoid using 3D numerical simulations Pei Shui, St\'{e}phane Popinet, Rama Govindarajan, Prashant Valluri The motion of an ellipsoidal solid in an ideal fluid has been shown to be chaotic (Aref, 1993) under the limit of non-integrability of Kirchhoff's equations (Kozlov \& Oniscenko, 1982). On the other hand, the particle could stop moving when the damping viscous force is strong enough. We present numerical evidence using our in-house immersed solid solver for 3D chaotic motion of a general ellipsoidal solid and suggest criteria for triggering such motion. Our immersed solid solver functions under the framework of the Gerris flow package of Popinet et al. (2003). This solver, the Gerris Immersed Solid Solver (GISS), resolves 6 degree-of-freedom motion of immersed solids with arbitrary geometry and number. We validate our results against the solution of Kirchhoff’s equations. The study also shows that the translational/ rotational energy ratio plays the key role on the motion pattern, while the particle geometry and density ratio between the solid and fluid also have some influence on the chaotic behaviour. Along with several other benchmark cases for viscous flows, we propose prediction of chaotic Aref's orbits as a key benchmark test case for immersed boundary/solid solvers. [Preview Abstract] |
Sunday, November 22, 2015 5:29PM - 5:42PM |
E9.00004: Modeling electrokinetic flow by Lagrangian particle-based method Wenxiao Pan, Kyungjoo Kim, Mauro Perego, Alexandre Tartakovsky, Mike Parks This work focuses on mathematical models and numerical schemes based on Lagrangian particle-based method that can effectively capture mesoscale multiphysics (hydrodynamics, electrostatics, and advection-diffusion) associated in applications of micro-/nano-transport and technology. The order of accuracy is significantly improved for particle-based method with the presented implicit consistent numerical scheme. Specifically, we show simulation results on electrokinetic flows and microfluidic mixing processes in micro-/nano-channel and through semi-permeable porous structures. [Preview Abstract] |
Sunday, November 22, 2015 5:42PM - 5:55PM |
E9.00005: Numerical study on influence of electric Reynolds and Peclet number's on electrohydrodynamic assisted atomization Patrick Sheehy, Mark Owkes Electrohydrodynamics (EHD) has shown great potential for enhancing the atomization of liquid flows by decreasing droplet size and improving dispersion. For many fluid flows relevant to engineering, such as liquid fuel injection, two important fluid properties are the electric Reynolds and Peclet numbers (Re and Pe), which control how fast electric charges relax to the gas-liquid interface and the thickness of electric charge boundary layers. The effect of the numbers is not well understood due to the difficulty of measuring electric charges experimentally. Additionally, predicting the impact of electric charge distribution on atomization is difficult. For example, a smaller electric Re number causes a weaker electric field, higher charge concentrations at interface, and a non-trivial distribution of the Coulomb force. This work uses a numerical approach to simulate a two-phase EHD jet in order to examine the affect of these two non-dimensional numbers on atomization quality. The approach employed is second-order, conservative, and consistently transports the discontinuous electric charge density, momentum, and phase interface. Several three-dimensional test cases are simulated using this process for a range of Re and Pe numbers and comparisons are made. [Preview Abstract] |
Sunday, November 22, 2015 5:55PM - 6:08PM |
E9.00006: A 3D MPI-Parallel GPU-accelerated framework for simulating ocean wave energy converters Ashish Pathak, Mehdi Raessi We present an MPI-parallel GPU-accelerated computational framework for studying the interaction between ocean waves and wave energy converters (WECs). The computational framework captures the viscous effects, nonlinear fluid-structure interaction (FSI), and breaking of waves around the structure, which cannot be captured in many potential flow solvers commonly used for WEC simulations. The full Navier-Stokes equations are solved using the two-step projection method, which is accelerated by porting the pressure Poisson equation to GPUs. The FSI is captured using the numerically stable fictitious domain method. A novel three-phase interface reconstruction algorithm is used to resolve three phases in a VOF-PLIC context. A consistent mass and momentum transport approach enables simulations at high density ratios. The accuracy of the overall framework is demonstrated via an array of test cases. Numerical simulations of the interaction between ocean waves and WECs are presented. [Preview Abstract] |
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