The draining of capillary liquids from containers with interior corners aboard the ISS

AbstractIn this work, we analyze liquid drains from containers in effective zero-g conditions aboard the International Space Station (ISS). The efficient draining of capillary fluids from conduits, containers, and media is critical in particular to high-value liquid samples such as minuscule biofluidics processing on earth and enormous cryogenic fuels management aboard spacecraft. The amount and rate of liquid drained can be of key concern. In the absence of strong gravitational effects, system geometry, and liquid wetting dominate capillary fluidic behavior. During the years 2010–2015, NASA conducted a series of handheld experiments aboard the ISS to observe “large” length scale capillary fluidic phenomena in a variety of irregular containers with interior corners. In this work, we focus on particular single exit port draining flows from such containers and digitize hours of archived NASA video records to quantify transient interface profiles and volumetric flow rates. These data are immediately useful for theoretical and numerical model benchmarks. We demonstrate this by making comparisons to lubrication models for slender flows in simplified geometries which show variable agreement with the data, in part validating certain geometry-dependent dynamical interface curvature boundary conditions while invalidating others. We further compare the data for the draining of complex vane networks and identify the limits of the current theory. All analyzed data is made available to the public as MATLAB files, as detailed within.

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The public-private partnership valuation paradox

Accounting Research Journal ◽

10.1108/arj-08-2020-0275 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Stephen Gray ◽

Jason Hall ◽

Grant Pollard ◽

Damien Cannavan

Keyword(s):

Mathematical Proof ◽

Systematic Risk ◽

Cash Flows ◽

Current Theory ◽

Apparent Paradox ◽

Content Type ◽

The Public ◽

The Past ◽

Alternative Approaches ◽

Practical Implications

Purpose In the context of public-private partnerships (PPPs), it has been argued that the standard valuation framework produces a paradox whereby government appears to be made better off by taking on more systematic risk. This has led to a range of approaches being applied in practice, none of which are consistent with the standard valuation approach. The purpose of this paper is to demonstrate that these approaches are flawed and unnecessary. Design/methodology/approach The authors step through the proposed alternative valuation approaches and demonstrate their inconsistencies and illogical outcomes, using theory, logic and mathematical proof. Findings In this paper, the authors demonstrate that the proposed (alternative) approaches suffer from internal inconsistencies and produce illogical outcomes in some cases. The authors also show that there is no problem with the current accepted theory and that the apparent paradox is not the result of a deficiency in the current theory but is rather caused by its misapplication in practice. In particular, the authors show that the systematic risk of cash flows is frequently mis-estimated, and the correction of this error solves the apparent paradox. Practical implications Over the past 20 years, PPP activity around the globe amounts to many billions of dollars. Decisions on major infrastructure funding are of enormous social and economic importance. Originality/value To the best of the authors’ knowledge, this study is the first to demonstrate the flaws and internal inconsistencies with proposed valuation framework alternatives for the purposes of evaluating PPPs.

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Gas-liquid flows through porous media in microgravity: Packed Bed Reactor Experiment-2

10.22541/au.163693261.16884082/v1 ◽

2021 ◽

Author(s):

Brian Motil ◽

Mahsa Taghavi ◽

Vemuri Balakotaiah ◽

Henry Nahra

Keyword(s):

Gas Flow ◽

Liquid Velocity ◽

Space Station ◽

Particle Diameter ◽

Packed Bed ◽

Packed Bed Reactor ◽

Flow Rates ◽

Test Conditions ◽

Superficial Gas Velocity ◽

Liquid Flows

Experimental results on pressure drop and gas hold-up for gas-liquid flow through packed beds obtained from a second flight on the International Space Station are presented and analyzed. It is found that the gas hold-up is a function of the bed history at low liquid and gas flow rates whereas higher gas hold-up and pressure gradients are observed for the test conditions following a liquid only pre-flow compared to the test conditions following a gas only pre-flow period. Over the range of flow rates tested, the capillary force is the dominant contributor to the pressure gradient and is found to be linear with the superficial liquid velocity but is a much weaker function of the superficial gas velocity. The capillary contribution is also a function of the particle size and varies approximately inversely with the particle diameter within the range of the test conditions.

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Small-to-Large Length Scale Transition of TMAO Interaction with Hydrophobic Solutes

Physical Chemistry Chemical Physics ◽

10.1039/d1cp05167a ◽

2021 ◽

Author(s):

Angelina Folberth ◽

Swaminath Bharadwaj ◽

Nico van der Vegt

Keyword(s):

Molecular Dynamics ◽

Free Energy ◽

Md Simulations ◽

Free Energy Calculations ◽

Length Scale ◽

Simulation Data ◽

Energy Calculations ◽

Large Length ◽

Hydrophobic Solutes ◽

Large Length Scale

We report the effect of trimethylamine N-oxide (TMAO) on the solvation of nonpolar solutes in water studied with molecular dynamics (MD) simulations and free-energy calculations. The simulation data indicate the...

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Chemical Inhomogeneities in Galaxies

International Astronomical Union Colloquium ◽

10.1017/s0252921100067373 ◽

1977 ◽

Vol 45 ◽

pp. 67-71 ◽

Cited By ~ 1

Author(s):

M. G. Edmunds

Keyword(s):

Interstellar Medium ◽

Chemical Evolution ◽

Galactic Disk ◽

Observational Evidence ◽

Galactic Evolution ◽

Length Scale ◽

Galactic Chemical Evolution ◽

Large Length ◽

Large Length Scale

The local chemical inhomogneity of the interstellar medium at a given time is an important factor in models of galactic chemical evolution. It can affect both the G-dwarf metallicity problem (Tinsley 1975, Talbot and Arnett 1973) and the correlation of the abundances of different elements (Tinsley 1976). Observational evidence of abundance gradients in our own Galaxy, and someothergalaxies (summarised by Peimbert 1975, van den Bergh 1975), implies that in homogeneities over a large length scale must be created and survive during galactic evolution. Brief consideration of the mixing of the Galactic disk (e.g. Edmunds 1975, 1976) suggests

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Excitation by Flow Over an Obstructed Opening

5th International Symposium on Fluid Structure International, Aeroeslasticity, and Flow Induced Vibration and Noise ◽

10.1115/imece2002-33374 ◽

2002 ◽

Cited By ~ 3

Author(s):

Paul J. Zoccola

Keyword(s):

Flow Field ◽

Resonant Excitation ◽

Cavity Resonance ◽

Length Scale ◽

Cavity Pressure ◽

Production Distribution ◽

Cavity Opening ◽

Large Length ◽

Flow Over A Cavity ◽

Large Length Scale

The effect on flow-induced cavity resonance of the presence of an obstruction, or a grid made up of regularly spaced obstructions, in the cavity opening is considered. The presence of a single obstruction or of a grid generally alters the flow so that the excitation occurs on the smaller length scale created by the obstruction. However, discussion of resonant excitation on the length scale encompassing the obstructions has not been found in the literature. For this study, measurements of cavity pressure due to flow over a cavity with obstructions or grids of varying dimensions in the opening were made. Measurements of the flow field around a single obstruction were also made. The cavity pressure measurements show that flow over an opening with a grid does result in the occurrence of classical resonant excitation at the large length scale. The frequency of the excitation and the amplitude of the response at the large length scale are reduced, depending on the dimensions of the obstruction. Flow field results show the effects that an obstruction has on the flow, including effects on the vortex convection velocity and the energy production distribution.

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Development of an Efficient Phase Separator for Space and Ground Applications

Volume 2, Fora: Advances in Fluids Engineering Education; Cavitation and Multiphase Flow; Fluid Measurements and Instrumentation ◽

10.1115/fedsm2016-7793 ◽

2016 ◽

Author(s):

Xiongjun Wu ◽

Greg Loraine ◽

Chao-Tsung Hsiao ◽

Georges L. Chahine

Keyword(s):

Swirling Flow ◽

Flow Behavior ◽

Space Station ◽

Low Flow ◽

Design Parameters ◽

Two Phase ◽

Flow Rates ◽

Void Fractions ◽

Wide Range ◽

Phase Separator

The limited amount of liquids and gases that can be carried to space makes it imperative to recycle and reuse these fluids for extended human operations. During recycling processes gas and liquid phases are often intermixed. In the absence of gravity, separating gases from liquids is challenging due to the absence of buoyancy. This paper discusses a phase separator that is capable of efficiently and reliably separating gas-liquid mixtures of both high and low void fractions in a wide range of flow rates that is applicable to reduced and zero gravity environments. The phase separator consists of two concentric cylindrical chambers. The fluid introduced in the space between the two cylinders enters the inner cylinder through tangential slots and generates a high intensity swirling flow. The geometric configuration is selected to make the vortex swirl intense enough to lead to early cavitation which forms a cylindrical vaporous core at the axis even at low flow rates. Taking advantage of swirl and cavitation, the phase separator can force gas out of the liquid into the central core of the vortex even at low void fraction. Gas is extracted from one end of the cylinder axial region and liquid is extracted from the other end. The phase separator has successfully demonstrated its capability to reduce mixture void fractions down to 10−8 and to accommodate incoming mixture gas volume fractions as high as 35% in both earth and reduced gravity flight tests. The phase separator is on track to be tested by NASA on the International Space Station (ISS). Additionally, the phase separator design exhibits excellent scalability. Phase separators of different dimensions, with inlet liquid flow rates that range from a couple of GPMs to a few tens of GPMs, have been built and tested successfully in the presence and absence of the gravity. Extensive ground experiments have been conducted to study the effects of main design parameters on the performance of the phase separator, such as the length and diameter of the inner cylinder; the size, location, and layout of injection slots and exit orifices, etc., on the swirling flow behavior, and on the gas extraction performance. In parallel, numerical simulations, utilizing a two-phase Navier-Stokes flow solver coupled with bubble dynamics, have been conducted extensively to facilitate the development of the phase separator. These simulations have enabled us to better understand the physics behind the phase separation and provided guideline for system parts optimization. This paper describes our efforts in developing the passive phase separator for both space and ground applications.

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Context matters: enablers and barriers to knowledge sharing in Australian public sector ICT projects

Journal of Knowledge Management ◽

10.1108/jkm-12-2019-0691 ◽

2020 ◽

Vol 24 (8) ◽

pp. 1921-1941

Author(s):

Yakub Karagoz ◽

Naomi Whiteside ◽

Axel Korthaus

Keyword(s):

Public Sector ◽

Knowledge Sharing ◽

Single Case ◽

Structured Interview ◽

Current Theory ◽

Future Research ◽

Content Type ◽

The Public ◽

Project Environment ◽

Starting Point

Purpose This paper aims to extend the theory relating to knowledge sharing barriers and enablers in the public sector information and communication technology (ICT) project context. Design/methodology/approach A case study method was used whereby project managers from each of the seven departments of the Victorian Public Sector in Australia were interviewed about their knowledge sharing practice. A semi-structured interview instrument based on Riege’s (2005) barrier framework was used to explore the barriers to knowledge sharing that they experienced as part of their work. Findings The study found that many of Riege’s (2005) barriers did not apply in the public sector ICT project environment, demonstrating that context matters. In addition, five enablers were identified, resulting in a new model of enablers and barriers to knowledge sharing in public sector ICT projects. Research limitations/implications This study focuses on a single case, the Victorian Public Sector, and consequently the results are not generalisable. Future research should explore the applicability of the model in other public sector ICT project contexts. Practical implications The study highlights the relationship between knowledge sharing and the project manager and the role it plays in project delivery. The model presented provides a starting point for public sector practitioners to develop their knowledge sharing practice, potentially enhancing project outcomes in the process. Originality/value This study examines barriers to knowledge sharing in an under-researched context, that of the public sector ICT project environment. It builds on current theory and provides insights for practitioners in the public sector.

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