Turbulence modulation and microbubble dynamics in vertical channel flow

被引:40
作者
Molin, D. [1 ]
Marchioli, C. [1 ,2 ]
Soldati, A. [1 ,2 ]
机构
[1] Univ Udine, Ctr Interdipartimentale Fluidodinam & Idraul, I-33100 Udine, Italy
[2] CISM, Dept Fluid Mech, I-33100 Udine, Italy
关键词
Microbubbles; Turbulence modulation; Direct numerical simulation; Lagrangian tracking; Two-way coupling; Lift force model; LIFT FORCE; NUMERICAL-SIMULATION; PARTICLE DISPERSION; PHYSICAL-MECHANISMS; DRAG REDUCTION; BUBBLES; LADEN; SPHERE; MOTION; HYDRODYNAMICS;
D O I
10.1016/j.ijmultiphaseflow.2012.01.010
中图分类号
O3 [力学];
学科分类号
08 ; 0801 ;
摘要
In this paper we examine the mutual interactions between microbubbles and turbulence in vertical channel flow. An Eulerian-Lagrangian approach based on pseudo-spectral direct numerical simulation is used: bubbles are momentum coupled with the fluid and are treated as pointwise spheres subject to gravity, drag, added mass, pressure gradient, Basset and lift forces. Two different flow configurations (upward and downward channel flow of water at shear Reynolds number Re-tau = 150) and four different bubble diameters are considered, assuming that bubbles are non-deformable (i.e. small Eotvos number) and contaminated by surfactants (i.e. no-slip condition applies at bubble surface). Confirming previous knowledge, we find macroscopically different bubble distribution in the two flow configurations, with lift segregating bubbles at the wall in upflow and preventing bubbles from reaching the near-wall region in downflow. Due to local momentum exchange with the carrier fluid and to the differences in bubble distribution, we also observe significant increase (resp. decrease) of both wall shear and liquid flowrate in upflow (resp. downflow). We propose a novel force scaling to examine results in vertical turbulent bubbly flows, which can help to judge differences in the turbulence features due to bubble presence. By examining two-phase flow energy spectra, we show that bubbles determine an enhancement (resp. attenuation) of energy at small (resp. large) flow scales, a feature already observed in homogeneous isotropic turbulence. Bubble-induced flow field modifications, in turn, alter significantly the dynamics of the bubbles and lead to different trends in preferential concentration and wall deposition. In this picture, a crucial role is played by the lift force, which is a delicate issue when accurate models of shear flows with bubbles are sought. We analyze and discuss all the observed trends emphasizing the impact that the lift force model has on the simulations. (C) 2012 Elsevier Ltd. All rights reserved.
引用
收藏
页码:80 / 95
页数:16
相关论文
共 52 条
[1]   Quantifying microbubble clustering in turbulent flow from single-point measurements [J].
Calzavarini, Enrico ;
Van den Berg, Thomas H. ;
Toschi, Federico ;
Lohse, Detlef .
PHYSICS OF FLUIDS, 2008, 20 (04)
[2]   Dynamics of a two-dimensional upflowing mixing layer seeded with bubbles: Bubble dispersion and effect of two-way coupling [J].
Climent, E. ;
Magnaudet, J. .
PHYSICS OF FLUIDS, 2006, 18 (10)
[3]   Large-scale simulations of bubble-induced convection in a liquid layer [J].
Climent, E ;
Magnaudet, J .
PHYSICAL REVIEW LETTERS, 1999, 82 (24) :4827-4830
[4]   PARTICLE-SOURCE IN CELL (PSI-CELL) MODEL FOR GAS-DROPLET FLOWS [J].
CROWE, CT ;
SHARMA, MP ;
STOCK, DE .
JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME, 1977, 99 (02) :325-332
[5]   A three-dimensional CFD model for gas-liquid bubble columns [J].
Delnoij, E ;
Kuipers, JAM ;
van Swaaij, WPM .
CHEMICAL ENGINEERING SCIENCE, 1999, 54 (13-14) :2217-2226
[6]   DIRECT SIMULATION OF PARTICLE DISPERSION IN A DECAYING ISOTROPIC TURBULENCE [J].
ELGHOBASHI, S ;
TRUESDELL, GC .
JOURNAL OF FLUID MECHANICS, 1992, 242 :655-700
[7]   ON PREDICTING PARTICLE-LADEN TURBULENT FLOWS [J].
ELGHOBASHI, S .
APPLIED SCIENTIFIC RESEARCH, 1994, 52 (04) :309-329
[8]   The rise of bubbles in a vertical shear flow [J].
Ervin, EA ;
Tryggvason, G .
JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME, 1997, 119 (02) :443-449
[9]   A direct numerical simulation study of the buoyant rise of bubbles at O(100) Reynolds number -: art. no. 093303 [J].
Esmaeeli, A ;
Tryggvason, G .
PHYSICS OF FLUIDS, 2005, 17 (09) :1-19
[10]   Diffusion of spherical bubbles in a turbulent boundary layer [J].
Felton, K ;
Loth, E .
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW, 2002, 28 (01) :69-92