Modeling Wall Film Formation and Breakup Using an Integrated Interface-Tracking/Discrete-Phase Approach

2010 ◽  
Vol 133 (3) ◽  
Author(s):  
M. Arienti ◽  
L. Wang ◽  
M. Corn ◽  
X. Li ◽  
M. C. Soteriou ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Level Set ◽  
Film Formation ◽  
Rectangular Channel ◽  
Grid Method ◽  
Direct Numerical Simulations ◽  
Liquid Jet ◽  
Two Phase ◽  
Local Flow ◽  
Air Jet

We propose a computationally tractable model for film formation and breakup based on data from experiments and direct numerical simulations. This work is a natural continuation of previous studies where primary atomization was modeled based on local flow information from a relatively low-resolution tracking of the liquid interface [Arienti and Soteriou, 2007, “Dynamics of Pulsed Jet in Crossflow,” ASME Paper No. GT2007-27816]. The submodels for film formation proposed here are supported by direct numerical simulations obtained with the refined level set grid method [Herrmann, 2008, “A Balanced Force Refined Level Set Grid Method for Two-Phase Flows on Unstructured Flow Solver Grids,” J. Comput. Phys., 227, pp. 2674–2706]. The overall approach is validated by a carefully designed experiment [Shedd et. al., 2009, “Liquid Jet Breakup by an Impinging Air Jet,” Forty-Seventh AIAA Aerospace Sciences Meeting. Paper No. AIAA-2009-0998], where the liquid jet is crossflow-atomized in a rectangular channel so that a film forms on the wall opposite to the injection orifice. The film eventually breaks up at the downstream exit of the channel. Comparisons with phase Doppler particle analyzer data and with nonintrusive film thickness point measurements complete this study.

Modeling Wall Film Formation and Breakup Using an Integrated Interface-Tracking/ Discrete-Phase Approach

2010 ◽  
Author(s):  
M. Arienti ◽  
L. Wang ◽  
M. Corn ◽  
X. Li ◽  
M. C. Soteriou ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Film Formation ◽  
Rectangular Channel ◽  
Cross Flow ◽  
Direct Numerical Simulations ◽  
Local Flow ◽  
Wall Film ◽  
Flow Information ◽  
Designed Experiment ◽  
Discrete Phase

We propose a computationally tractable model for film formation and breakup based on data from experiments and direct numerical simulations. This work is a natural continuation of previous studies where primary atomization is modeled based on local flow information from a relatively low-resolution tracking of the liquid interface [1]. Sub-models for film formation are supported by direct numerical simulations obtained with the Refined Level Set Grid (RLSG) method [2]. The overall approach is validated by a carefully designed experiment [3], where the liquid jet is cross flow-atomized in a rectangular channel so that a film forms on the wall opposite to the injection orifice. The film eventually breaks up at the downstream exit of the channel. Comparisons with Phase Doppler Particle Analyzer (PDPA) data and with non-intrusive film thickness point measurements complete this study.

A Validated Two-Phase Flow Large Eddy Simulation Methodology

2013 ◽  
Author(s):  
Feng Xiao ◽  
Mehriar Dianat ◽  
James J. McGuirk
Keyword(s):  
Boundary Conditions ◽  
Level Set ◽  
Two Phase Flow ◽  
Local Level ◽  
Density Ratio ◽  
Cross Flow ◽  
Liquid Jet ◽  
Phase Flow ◽  
Two Phase ◽  
Primary Breakup

A robust two-phase flow LES methodology is described, validated and applied to simulate primary breakup of a liquid jet injected into an airstream in either co-flow or cross-flow configuration. A Coupled Level Set and Volume of Fluid method is implemented for accurate capture of interface dynamics. Based on the local Level Set value, fluid density and viscosity fields are treated discontinuously across the interface. In order to cope with high density ratio, an extrapolated liquid velocity field is created and used for discretisation in the vicinity of the interface. Simulations of liquid jets discharged into higher speed airstreams with non-turbulent boundary conditions reveals the presence of regular surface waves. In practical configurations, both air and liquid flows are, however, likely to be turbulent. To account for inflowing turbulent eddies on the liquid jet interface primary breakup requires a methodology for creating physically correlated unsteady LES boundary conditions, which match experimental data as far as possible. The Rescaling/Recycling Method is implemented here to generate realistic turbulent inflows. It is found that liquid rather than gaseous eddies determine the initial interface shape, and the downstream turbulent liquid jet disintegrates much more chaotically than the non-turbulent one. When appropriate turbulent inflows are specified, the liquid jet behaviour in both co-flow and cross-flow configurations is correctly predicted by the current LES methodology, demonstrating its robustness and accuracy in dealing with high liquid/gas density ratio two-phase systems.

Experimental Measurements and Numerical Simulations of Two-Phase Stratified, Wavy and Slug Flow in a Narrow Rectangular Channel

2005 ◽  
Author(s):  
Steven P. O’Halloran ◽  
B. Terry Beck ◽  
Mohammad H. Hosni ◽  
Steven J. Eckels
Keyword(s):  
Numerical Simulations ◽  
Slug Flow ◽  
Two Phase Flow ◽  
Rectangular Channel ◽  
Measurement Techniques ◽  
Narrow Channel ◽  
Experimental Measurements ◽  
Phase Flow ◽  
Two Phase ◽  
Two Fluids

Flow pattern transitions in two-phase flow are important phenomena for many different types of engineering applications, including heat exchangers. While two-phase flow is not understood as well as single-phase flow, advancements in both measurement techniques and numerical simulations are helping to increase the understanding of two-phase flow. In this paper, stratified/wavy flow is investigated, along with the transition from wavy to slug flow. For the experimental setup, a narrow channel with a length of 600 mm, height of 40 mm, and a width of 15 mm was fabricated using clear acrylic plastic, and water and air were the two fluids used for testing. The water in the channel was initially at rest, and the transition in flow patterns was created by increasing the velocity of air flowing over the water surface. Particle image velocimetry (PIV) was used to measure the velocity of the flow for stratified and wavy flow conditions, and also the velocity at the onset of slug flow. Along with the experimental measurements, computational fluid dynamics (CFD) simulations were conducted on a similar geometry using the volume of fluid (VOF) two-phase model. A commercial CFD software package was used for the simulations, and comparisons were made between the experimental measurements and numerical results. Favorable agreement was found between the experimental measurements and the numerical simulations. In particular, the transition from wavy to slug flow compared well to previously developed two-phase flow transition models, including the slug transition developed by Taitel and Dukler.

scholarly journals Direct numerical simulations of two-phase immiscible wakes

2014 ◽  
Vol 46 (4) ◽  
pp. 041409 ◽  
Author(s):  
Luca Biancofiore ◽  
François Gallaire ◽  
Patrice Laure ◽  
Elie Hachem
Keyword(s):  
Numerical Simulations ◽  
Direct Numerical Simulations ◽  
Two Phase

Detached direct numerical simulations of turbulent two-phase bubbly channel flow

2011 ◽  
Vol 37 (6) ◽  
pp. 647-659 ◽  
Author(s):  
Igor A. Bolotnov ◽  
Kenneth E. Jansen ◽  
Donald A. Drew ◽  
Assad A. Oberai ◽  
Richard T. Lahey ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Channel Flow ◽  
Direct Numerical Simulations ◽  
Two Phase

Direct numerical simulations of autoignition in turbulent two-phase flows

2009 ◽  
Vol 32 (2) ◽  
pp. 2275-2282 ◽  
Author(s):  
P. Schroll ◽  
A.P. Wandel ◽  
R.S. Cant ◽  
E. Mastorakos
Keyword(s):  
Numerical Simulations ◽  
Direct Numerical Simulations ◽  
Two Phase Flows ◽  
Two Phase

Detailed Numerical Simulations of the Primary Atomization of a Turbulent Liquid Jet in Crossflow

2009 ◽  
Author(s):  
Marcus Herrmann
Keyword(s):  
Level Set ◽  
Phase Interface ◽  
Grid Method ◽  
Point Particle ◽  
Small Scale ◽  
Liquid Jet ◽  
Jet In Crossflow ◽  
Accurate Treatment ◽  
Simulation Results ◽  
Actual Geometry

This paper presents numerical simulation results of the primary atomization of a turbulent liquid jet injected into a gaseous crossflow. Simulations are performed using the balanced force Refined Level Set Grid method. The phase interface during the initial breakup phase is tracked by a level set method on a separate refined grid. A balanced force finite volume algorithm together with an interface projected curvature evaluation is used to ensure the stable and accurate treatment of surface tension forces even on small scales. Broken off, small scale nearly spherical drops are transferred into a Lagrangian point particle description allowing for full two-way coupling and continued secondary atomization. The numerical method is applied to the simulation of the primary atomization region of a turbulent liquid jet (q = 6.6, We = 330, Re = 14,000) injected into a gaseous crossflow (Re = 570,000), analyzed experimentally by Brown and McDonell (2006). The simulations take the actual geometry of the injector into account. Grid converged simulation results of the jet penetration agree well with experimentally obtained correlations. Both column/bag breakup and shear/ligament breakup modes can be observed on the liquid jet. A grid refinement study shows that on the finest employed grids (flow solver 64 points per injector diameter, level set solver 128 points per injector diameter), grid converged drop sizes are achieved for drops as small as one-hundredth the size of the injector diameter.

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