Coupled flow phenomena in thin free-surface films

1975 ◽  
Vol 30 (6) ◽  
pp. 453-468
Author(s):  
C. H. Gartside ◽  
J. F. Osterle
Keyword(s):  
Free Surface ◽  
Surface Films ◽  
Coupled Flow ◽  
Flow Phenomena

Analytical Transport Network Theory for Onsager, Coupled Flows: Part 1—Channel-Scale Modeling of Linear, Electrokinetic Flow

2020 ◽  
Vol 18 (2) ◽  
Author(s):  
Alex P. Cocco ◽  
Kyle N. Grew
Keyword(s):  
Three Dimensional ◽  
Initial Step ◽  
Transport Network ◽  
Scale Model ◽  
Coupled Flow ◽  
Electrokinetic Flow ◽  
Element Analysis ◽  
Onsager Reciprocity ◽  
Flow Phenomena ◽  
Flow Through

Abstract The analytical transport network (ATN) model for flow through microstructural networks is extended to linearly coupled flows subject to Onsager reciprocity. Electrokinetic flow is used as an example system. Through the extension, we gain an improved understanding of if, and how, morphology and topology influence coupled flow systems differently than un-coupled flows. In Part 1, a channel-scale model is developed to describe electrokinetic flow through a channel of arbitrary morphology. The analytical model agrees well with finite element analysis (FEA), but is significantly less expensive in terms of computational resources, and, furthermore, offers general insight into morphology's additional influence on coupled flows relative to uncoupled flows. In Part 2, we exploit these savings to develop a computationally economical, network-scale model and associated algorithm for its implementation to voxel-based three-dimensional images. Included in the algorithm is a means for rapidly calculating a structure's tortuosity factor. This modeling effort represents an important initial step in extending the ATN approach to coupled flow phenomena relevant to emerging technologies that rely on heterogeneous, hierarchical materials.

A note on free-surface films in fractures

2012 ◽  
Vol 49 ◽  
pp. 72-75 ◽  
Author(s):  
Kevin M. Hayden ◽  
Aleksey S. Telyakovskiy ◽  
Stephen W. Wheatcraft
Keyword(s):  
Free Surface ◽  
Surface Films

Surface-wave damping in closed basins

1967 ◽  
Vol 297 (1451) ◽  
pp. 459-475 ◽  
Keyword(s):  
Free Surface ◽  
Viscous Dissipation ◽  
Gravity Waves ◽  
Surface Film ◽  
Phase Interface ◽  
Decay Rates ◽  
Surface Films ◽  
Surface Boundary ◽  
Capillary Hysteresis ◽  
Closed Basins

The damping of surface waves in closed basins appears to be due to ( a ) viscous dissipation at the boundary of the surrounding basin, ( b ) viscous dissipation at the surface in consequence of surface contamination, and ( c ) capillary hysteresis associated with the meniscus surrounding the free surface. Boundary layer approximations are invoked in the treatment of ( a ) and ( b ) to reproduce and extend results that have been obtained previously by more cumbersome procedures. The surface film is assumed to act as a linear, viscoelastic surface and may be either insoluble or soluble; however, the relaxation time for the equilibrium of soluble films is neglected relative to the period of the free-surface oscillations. Capillary hysteresis is analysed on the hypothesis that both the advance and recession of a meniscus are opposed by constant forces that depend only on the material properties of the three-phase interface. The theoretical results for the logarithmic decrements of gravity waves in circular and rectangular cylinders are compared with the decay rates observed by Case & Parkinson and by Keulegan, which typically exceeded the theoretical value based on wall damping alone by factors of between two and three. It is concluded that both surface films and capillary hysteresis can account for, and are likely to have contributed to, these observed discrepancies. The theoretical effect of a surface film on wind-generated gravity waves is examined briefly and is found to be consistent with the observation that the addition of detergent to water can increase the minimum wind speed (required to produce waves) by one order of magnitude.

A conceptual method to assess ship-helicopter dynamic interface

2020 ◽  
Vol 234 (5) ◽  
pp. 1092-1116 ◽  
Author(s):  
Shrish Shukla ◽  
Sidh N Singh ◽  
Sawan S Sinha ◽  
R Vijayakumar
Keyword(s):  
Flow Characteristics ◽  
Design Tool ◽  
Design Criteria ◽  
Computational Techniques ◽  
Complex Flow ◽  
Coupled Flow ◽  
Velocity Gradients ◽  
Dynamic Interface ◽  
Flow Phenomena ◽  
The Impact

The combined operation of a ship and a helicopter is ubiquitous in every naval organization. The operation of a ship in combination with the landing and take-off operations of a helicopter results in a very complex flow phenomenon. This is due to the presence of ship airwakes, strong velocity gradients and widely varying turbulence length scales. An accurate assessment of the resultant flow phenomena is an outstanding challenge for naval architects as well as researchers. A conceptual method to gain insight into the combined ship-helo flow phenomena over a helodeck is presented. The prime objective of this work is to develop an economical design tool employing both experimental as well as computational techniques to simulate the ship-helicopter coupled environment regime at early design stages reasonably well so as to ease the burden of expensive and risky sea trials. For this purpose, a simplified dynamic interface (SDI) model is proposed to investigate the coupled effects of ship airwake and helicopter rotor downwash. The paper reports a parametric analysis to study the coupled ship-helo airwake behaviour and its impact on helicopter fuselage over the ship helodeck for different ship speed regimes by the proposed SDI model. Further, an attempt has been made to set up preliminary design criteria to grade the ship-helicopter interface for ensuring minimum standards of safe helo operations. Finally, we discuss the impact of the coupled flow dynamics in terms of induced fuselage drag, cross-flow characteristics, rotor plane wake and velocity gradients existing over the helodeck region and evaluate the proposed design criteria.

Analysis of the Liquid Flow in a Vessel with a Rotating Disk at the Liquid Surface

2014 ◽  
Vol 35 (1) ◽  
pp. 3-18 ◽  
Author(s):  
Witold Suchecki
Keyword(s):  
Free Surface ◽  
Flow Velocity ◽  
Liquid Flow ◽  
Liquid Velocity ◽  
Rotating Disk ◽  
Velocity Fields ◽  
Cylindrical Coordinate ◽  
Disc Rotation ◽  
Flow Phenomena ◽  
The Relationship

Abstract This study is concerned with liquid flow induced by a disk which rotates steadily around its axis and touches the free surface of liquid contained in a cylindrical vessel. It is a simplified model of the flow in the inlet part of a vertical cooling crystallizer where a rotary distributor of inflowing solution is situated above the free surface of solution contained in the crystalliser. Numerical simulations of flow phenomena were conducted and the simulation results were interpreted assuming an analogy with Kármán’s theoretical equations. In a cylindrical coordinate system, the components of flow velocity were identified as functions of distance from the surface of the rotating disk. The experimental setup was developed to measure velocity fields, using digital particle velocimetry and optical flow. Conclusions concerning the influence of disc rotation on liquid velocity fields were presented and the experimental results were found to confirm the results of numerical simulation. On the basis of simulation data, an approximation function was determined to describe the relationship between the circumferential component of flow velocity and the distance from the disk.

scholarly journals A Computational Method for Free Surface Hydrodynamics

1981 ◽  
Vol 103 (2) ◽  
pp. 136-141 ◽  
Author(s):  
C. W. Hirt ◽  
B. D. Nichols
Keyword(s):  
Free Surface ◽  
Computational Method ◽  
Free Fluid ◽  
Immiscible Fluid ◽  
Fluid Interfaces ◽  
Vapor Bubbles ◽  
Piping Systems ◽  
Flow Phenomena ◽  
A New Technique ◽  
Local Average

There are numerous flow phenomena in pressure vessel and piping systems that involve the dynamics of free fluid surfaces. For example, fluid interfaces must be considered during the draining or filling of tanks, in the formation and collapse of vapor bubbles, and in seismically shaken vessels that are partially filled. To aid in the analysis of these types of flow phenomena, a new technique has been developed for the computation of complicated free-surface motions. This technique is based on the concept of a local average volume of fluid (VOF) and is embodied in a computer program for two-dimensional, transient fluid flow called SOLA-VOF. The basic approach used in the VOF technique is briefly described, and compared to other free-surface methods. Specific capabilities of the SOLA-VOF program are illustrated by generic examples of bubble growth and collapse, flows of immiscible fluid mixtures, and the confinement of spilled liquids.

Large Interface Simulation in Multiphase Flow Phenomena

2006 ◽  
Author(s):  
Aparicio Henriques ◽  
Pierre Coste ◽  
Sylvain Pigny ◽  
Jacques Magnaudet
Keyword(s):  
Free Surface ◽  
Large Scale ◽  
Fluid Model ◽  
Surface Tension Force ◽  
Recognition Algorithm ◽  
Small Scale ◽  
Rising Bubble ◽  
Flow Phenomena ◽  
Two Fluid Model ◽  
Two Fluid

An attempt to represent multiphase multiscale flow, filling the gap between Direct Numerical Simulation (DNS) and averaged approaches, is the purpose of this paper. We present a kind of Large Interface (LI) simulation formalism obtained after a filtering process on local instantaneous conservation equations of the two-fluid model which distinguishes between small scales and large scales contributions. LI surface tension force is also taken into account. Small scale dynamics call for modelisation and large scale for simulation. Joined to this formalism, a criterion to recognize LI’s is developped. It is used in an interface recognition algorithm which is qualified on a sloshing case and a bubble oscillation under zero-gravity. This method is applied to a rising bubble in a pool that collapses at a free surface and to a square-base basin experiment where splashing and sloshing at the free surface are the main break-up phenomena.

An implicit 2D hydrodynamic numerical model for free surface-subsurface coupled flow problems

2018 ◽  
Vol 87 (7) ◽  
pp. 343-357 ◽  
Author(s):  
Naser Shokri ◽  
Masoud Montazeri Namin ◽  
Javad Farhoudi
Keyword(s):  
Free Surface ◽  
Numerical Model ◽  
Coupled Flow ◽  
Flow Problems
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