A Comprehensive Sub-Grid Air Entrainment Model for RaNS Modeling of Free-Surface Bubbly Flows

The simulation of free surface bubbly flows using a two-fluid model remains a challenging problem in part due to the lack of a comprehensive air entrainment model that can predict the rate and location of air entrainment for a wide range of flows. In this study we derive a sub-grid model and implement it in a computational multiphase fluid dynamics (CMFD) framework to solve the Reynolds-averaged two-fluid equations. We assess the performance of our model in simulating bubbly flows underneath a plunging liquid jet and a hydraulic jump while varying the characteristic velocity. We compare the void fraction predictions with their experimental counterparts and conclude that the air entrainment model and the two-fluid modeling approach yield accurate results everywhere for the plunging jet and in the turbulent shear layer for the hydraulic jump. The inability of the proposed approach to recover the high void fraction in the roller region of the hydraulic jump is attributed to the failure of RaNS model to resol...

[1]  Helmut Kobus,et al.  Local air entrainment and detrainment , 1984 .

[2]  Peter D. Cummings.  Aeration Due to Breaking Waves , 1996 .

[3]  Hubert Chanson,et al.  Physical modelling and similitude of air bubble entrainment at vertical circular plunging jets , 2004 .

[4]  Azat Yu. Galimov.  An analysis of interfacial waves and air ingestion mechanisms , 2007 .

[5]  Juan C. Lasheras,et al.  On the breakup of an air bubble injected into a fully developed turbulent flow. Part 1. Breakup frequency , 1999, Journal of Fluid Mechanics.

[6]  Kazuaki Yamagiwa,et al.  Gas Holdup and Gas Entrainment Rate in Downflow Bubble Column with Gas Entrainment by a Liquid Jet Operating at High Liquid Throughput , 1990 .

[7]  D. Drew,et al.  A center-averaged two-fluid model for wall-bounded bubbly flows , 2006 .

[8]  C. W. Hirt,et al.  Modeling Entrainment of Air at Turbulent Free Surfaces , 2004 .

[9]  F. Menter.  Two-equation eddy-viscosity turbulence models for engineering applications , 1994 .

[10]  A. K. Biń.  Gas entrainment by plunging liquid jets , 1988 .

[11]  Akio Tomiyama,et al.  Multi-fluid simulation of turbulent bubbly pipe flows , 2009 .

[12]  Frederick Stern,et al.  Unsteady RANS simulation of the ship forward speed diffraction problem , 2006 .

[13]  Eamon McKeogh,et al.  Air entrainment rate and diffusion pattern of plunging liquid jets , 1981 .

[14]  J. Lasheras,et al.  Dynamics of large turbulent structures in a steady breaker , 2011 .

[15]  Frederick Stern,et al.  GENERAL-PURPOSE PARALLEL UNSTEADY RANS SHIP HYDRODYNAMICS CODE: CFDSHIP-IOWA , 2003 .

[16]  Hubert Chanson,et al.  Turbulence measurements in the bubbly flow region of hydraulic jumps , 2008 .

[17]  Assad A. Oberai,et al.  A quantitative sub-grid air entrainment model for bubbly flows , 2009 .

[18]  Donald A. Drew,et al.  A sub-grid air entrainment model for breaking bow waves and naval surface ships , 2008 .

[19]  Dominique Legendre,et al.  The lift force on a spherical bubble in a viscous linear shear flow , 1998, Journal of Fluid Mechanics.

[20]  F. Stern,et al.  A coupled level set and volume-of-fluid method for sharp interface simulation of plunging breaking waves , 2009 .

[21]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[22]  Eamon McKeogh,et al.  EFFECT OF TURBULENCE INTENSITY ON THE RATE OF AIR ENTRAINMENT BY PLUNGING WATER JETS. , 1980 .

[23]  S. Osher,et al.  A level set approach for computing solutions to incompressible two-phase flow , 1994 .

[24]  J. Hunt.  TURBULENCE STRUCTURE AND TURBULENT DIFFUSION NEAR GAS-LIQUID INTERFACES , 1984 .

[25]  Hubert Chanson,et al.  Air Bubble Entrainment in Free-Surface Turbulent Shear Flows , 1996 .

[26]  J. Kirby,et al.  MODELING OF SURFZONE BUBBLES USING A MULTIPHASE VOF MODEL , 2009 .

[27]  J. Donk.  Water aeration with plunging jets , 1981 .

[28]  R. Lahey.  The simulation of multidimensional multiphase flows , 2005 .

[29]  D. Drew,et al.  Theory of Multicomponent Fluids , 1998 .

[30]  Hubert Chanson,et al.  Air entrapment and air bubble dispersion at two-dimensional plunging water jets (vol 53, pg 4113, 1998) , 1998 .

[31]  D. Drew,et al.  A Particle-Center-Averaged Two-Fluid Model for Wall-Bounded Bubbly Flows , 2002 .

[32]  K. J. Sene,et al.  Air entrainment by plunging jets , 1988 .

[33]  Hubert Chanson,et al.  Experimental study of the air–water shear flow in a hydraulic jump , 2000 .

[34]  Frederick Stern,et al.  An unsteady single‐phase level set method for viscous free surface flows , 2007 .

[35]  Shirley Dex,et al.  JR 旅客販売総合システム（マルス）における運用及び管理について , 1991 .

[36]  Da Ervine,et al.  BEHAVIOUR OF TURBULENT WATER JETS IN THE ATMOSPHERE AND IN PLUNGE POOLS. , 1987 .

[37]  Hubert Chanson,et al.  Similitude of Air Bubble Entrainment and Dispersion in Vertical Circular Plunging Jet Flows. An Experimental Study with Freshwater, Salty Freshwater and Seawater , 2002 .

[38]  Hubert Chanson,et al.  Turbulence in Hydraulic Jumps: Experimental Measurements , 2007 .