A modeling approach to droplet contact-line motion dynamics in high-density-ratio two-phase flow

2013 ◽  
Vol 73 ◽  
pp. 175-186 ◽  
Author(s):  
Rongye Zheng ◽  
Jinju Sun ◽  
Haihu Liu
Keyword(s):  
Contact Line ◽  
Two Phase Flow ◽  
Density Ratio ◽  
High Density ◽  
Phase Flow ◽  
Two Phase ◽  
Modeling Approach ◽  
High Density Ratio ◽  
Contact Line Motion ◽  
Motion Dynamics

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.

A Combined Volume of Fluid and Immersed Boundary Method for Modelling of Two-Phase Flows with High Density Ratio

2021 ◽  
Author(s):  
Qiu Jin ◽  
Dominic Hudson ◽  
W.G. Price
Keyword(s):  
Boundary Layer ◽  
Immersed Boundary Method ◽  
Density Ratio ◽  
Volume Of Fluid ◽  
High Density ◽  
Immersed Boundary ◽  
Two Phase Flows ◽  
Two Phase ◽  
Boundary Method ◽  
High Density Ratio

Abstract A combined volume of fluid and immersed boundary method is developed to simulate two-phase flows with high density ratio. The problems of discontinuity of density and momentum flux are known to be challenging in simulations. In order to overcome the numerical instabilities, an extra velocity field is designed to extend velocity of the heavier phase into the lighter phase and to enforce a new boundary condition near the interface, which is similar to non-slip boundary conditions in Fluid-Structure Interaction (FSI) problems. The interface is captured using a Volume of Fluid (VOF) method, and a new boundary layer is built on the lighter phase side by an immersed boundary method. The designed boundary layer helps to reduce the spurious velocity caused by the imbalance of dynamic pressure gradient and density gradient and to prevent tearing of the interface due to the tangential velocity across the interface. The influence of time step, density ratio, and spatial resolution is studied in detail for two set of cases, steady stratified flow and convection of a high-density droplet, where direct comparison is possible to potential flow analysis (i.e. infinite Reynold's number). An initial study for a droplet splashing on a thin liquid film demonstrates applicability of the new solver to real-life applications. Detailed comparisons should be performed in the future for finite Reynold's number cases to fully demonstrate the improvements in accuracy and stability of high-density ratio two-phase flow simulations offered by the new method.

Vibration of a Tube Bundle in Two-Phase Freon Cross-Flow

1995 ◽  
Vol 117 (4) ◽  
pp. 321-329 ◽  
Author(s):  
M. J. Pettigrew ◽  
C. E. Taylor ◽  
J. H. Jong ◽  
I. G. Currie
Keyword(s):  
Two Phase Flow ◽  
Tube Bundle ◽  
Density Ratio ◽  
Cross Flow ◽  
Flow Regimes ◽  
Phase Flow ◽  
Two Phase ◽  
Void Fractions ◽  
Fluidelastic Instability ◽  
First Results

Two-phase cross-flow exists in many shell-and-tube heat exchangers. The U-bend region of nuclear steam generators is a prime example. Testing in two-phase flow simulated by air-water provides useful results inexpensively. However, two-phase flow parameters, in particular surface tension and density ratio, are considerably different in air-water than in steam-water. A reasonable compromise is testing in liquid-vapor Freon, which is much closer to steam-water while much simpler experimentally. This paper presents the first results of a series of tests on the vibration behavior of tube bundles subjected to two-phase Freon cross-flow. A rotated triangular tube bundle of tube-to-diameter ratio of 1.5 was tested over a broad range of void fractions and mass fluxes. Fluidelastic instability, random turbulence excitation, and damping were investigated. Well-defined fluidelastic instabilities were observed in continuous two-phase flow regimes. However, intermittent two-phase flow regimes had a dramatic effect on fluidelastic instability. Generally, random turbulence excitation forces are much lower in Freon than in air-water. Damping is very dependent on void fraction, as expected.

scholarly journals A Connectivity-Based Modeling Approach for Representing Hysteresis in Macroscopic Two-Phase Flow Properties

2014 ◽  
Vol 63 ◽  
pp. 3456-3463 ◽  
Author(s):  
Abdullah Cihan ◽  
Jens Birkholzer ◽  
Luca Trevisan ◽  
Marco Bianchi ◽  
Quanlin Zhou ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Phase Flow ◽  
Flow Properties ◽  
Two Phase ◽  
Modeling Approach

scholarly journals Modeling of contact line dynamics for two-phase flow

PAMM ◽  
2007 ◽  
Vol 7 (1) ◽  
pp. 1141603-1141604
Author(s):  
Gunilla Kreiss
Keyword(s):  
Contact Line ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Contact Line Dynamics
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