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This paper provides an historical perspective of the involvement of Prof. J.C. Legros in microgravity research during aircraft parabolic flights. Prof. Legros conducted 27 experiments during 33 campaign of microgravity research organised by the European Space Agency. Nearly all fields of fluid physics were investigated in microgravity by this indefatigable scientist. This paper gives a non-exhaustive summary of some experiments conducted by Prof. Legros during these 33 campaigns. [ABSTRACT FROM AUTHOR]

Thin liquid films on isothermal substrates, where the film is flat and parallel to the substrate, succumb to thermocapillary instabilities and rupture, forming local hot-spots. These long wavelength instabilities are specific to aspect ratios where the liquid film mean thickness is several orders of magnitude less than the substrate characteristic dimension. Absent stabilizing gravitational acceleration, the growth rate of thermocapillary instabilities is further intensified, driving the film to rupture even earlier. Numerical simulations of zero gravity dynamics of Newtonian liquid films on a solid, horizontal, isothermal substrate were conducted. When the solid, isothermal substrate was replaced with a one-dimensionally porous substrate, was fully saturated with the same fluid as the liquid film, and was deep enough to accommodate all the liquid on it, we observed that destabilizing spatial modes were damped thereby preventing rupture and prolonging the film lifespan. This nonlinear evolution was visualized and quantified using recurrence plots. [ABSTRACT FROM AUTHOR]

A technique for calculating the two-phase flows at liquid fuel atomization by the air injector is developed. In the course of numerical experiments, the flow parameter distributions over the cross section and volume for different nozzle design options are obtained. The influence of the twist angle of the gas flow on the liquid fuel atomization is analyzed. [ABSTRACT FROM AUTHOR]

Most computational fluid dynamics simulations are, at present, performed in a body-fixed frame, for aeronautical purposes. With the advent of sharp manoeuvre, which may lead to transient effects originating in the acceleration of the centre of mass, there is a need to have a consistent formulation of the Navier-Stokes equations in an arbitrarily moving frame. These expressions should be in a form that allows terms to be transformed between non-inertial and inertial frames and includes gravity, viscous terms, and linear and angular acceleration. Since no effects of body acceleration appear in the inertial frame Navier-Stokes equations themselves, but only in their boundary conditions, it is useful to investigate acceleration source terms in the non-inertial frame. In this paper, a derivation of the energy equation is provided in addition to the continuity and momentum equations previously published. Relevant dimensionless constants are derived which can be used to obtain an indication of the relative significance of acceleration effects. The necessity for using computational fluid dynamics to capture nonlinear effects remains, and various implementation schemes for accelerating bodies are discussed. This theoretical treatment is intended to provide a foundation for interpretation of aerodynamic effects observed in manoeuvre, particularly for accelerating missiles. [ABSTRACT FROM AUTHOR]

Wickless heat pipes are being studied for use in cooling critical components of spacecraft. The wickless design is thought to produce a simpler and lighter heat transfer system than heat pipes containing wicks or mechanically driven systems. The constrained vapor bubble experiment (CVB) is one such system tested on the International Space Station where the Bond Number (ratio of gravitational force to surface force) is small maximizing the affects of capillarity. The CVB is essentially a square, fused silica spectrophotometer cuvette evacuated and then partially filled with pentane as the working fluid. Along with temperature and pressure measurements, the two-dimensional thickness profile of the menisci formed at the corners of the quartz cuvette was determined using an interferometry based system contained with the station’s Light Microscopy Module (LMM). The CVB can be viewed as a hollow fin and its behavior analyzed using a simple, one-dimensional heat transfer model. That model, coupled with the visual observation of the vapor–liquid distribution inside the fin, provides an enhanced understanding of what the measured temperature and pressure profiles represent and the heat transfer mechanisms controlling the operation of the device. The internal heat transfer processes were found to be very complicated, multi-dimensional, and greatly dependent on internal and external radiative heat transfer. Internal radiative exchange was found to be more significant than originally anticipated as was the effect Marangoni forces on internal convective heat transfer. An analysis of the temperature profiles in conjunction with vapor–liquid interface mapping showed that the system could be separated into a number of discrete operation zones depending on the dominant mode of heat transfer. [ABSTRACT FROM AUTHOR]

At the dawn of the Space Age, the design of early rocket and spacecraft systems presented significant challenges because of the low-gravity environment of space. Motivated by these challenges, the National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) pioneered the development of low-gravity facilities-including drop towers, sounding rockets, zero-gravity (zero-g) aircraft, and most importantly, space-based facilities-to advance microgravity research to further the nation's space exploration efforts. These efforts resulted in improved spacecraft system designs and practices in areas as diverse as fluid handling and spacecraft fire safety. At the same time, researchers realized that the microgravity environment allows the study of fundamental combustion and fluid physics problems, without the complication of buoyancy-induced convection. Microgravity testing enabled advancements in areas of technological and ecological importance in terrestrial applications such as global atmospheric change, combustor design, groundwater pollution, oil production, and advanced materials manufacturing, which often rely on advances in fluid physics and chemically reacting flows. GRC has been a leader in microgravity fluid physics and combustion research for more than 50 years. This paper highlights the facilities and some of the many accomplishments. [ABSTRACT FROM AUTHOR]

Purpose – This paper aims to utilize purpose advanced fluid-structure interaction, non-linear dynamics, finite-element analyses in order to investigate various phenomena and processes accompanying blast wave generation, propagation and interaction and to assess the blast-wave-mitigation potential of a piston-cylinder assembly placed in front of the target structure. Design/methodology/approach – The employed computational methods and tools are verified and validated by first demonstrating that they can quite accurately reproduce analytical solutions for a couple of well-defined blast wave propagation and interaction problems. Findings – The methods/tools are used to investigate the piston-cylinder blast-mitigation concept and the results obtained clearly reveal that significant blast-mitigation effects can be achieved through the use of this concept. Furthermore, the results showed that the extent of the blast-mitigation effect is a sensitive function of the piston-cylinder geometrical parameters. Specifically, the mass of the piston and the length of the cylinder are found to be the dominant factors controlling the extent of the blast-wave-mitigation. Originality/value – The work demonstrates that, when assessing the blast-wave-mitigation potential of the piston-cylinder concept, it is critical that loading experienced by the piston be defined by explicitly modeling (fluid/structure) interactions between the blast wave(s) and the piston. [ABSTRACT FROM AUTHOR]

The effects of small vibrations on a particle oscillating near a solid wall in a fluid cell, relevant to material processing such as crystal growth in space, have been investigated by three dimensional direct numerical simulations. Simulations have been conducted for a solid spherical particle suspended in a fluid cell filled with a fluid of 1 cSt viscosity, vibrating sinusoidally in a horizontal direction. The simulations revealed the existence of a vibration-induced force attracting the particle towards the nearest cell wall which varied with the cell vibration frequency. The mechanism for this attraction force as well as an example showing the effects of this force on the particle are presented in this paper. The predicted flow patterns around the particle unveiled an accelerated flow in the gap between the particle and the nearest wall as well as a pressure decrease in accordance with Bernoulli's principle, which would result in the attraction force. [ABSTRACT FROM AUTHOR]

November 20, 2010, marked a significant milestone in the annals of human endeavors in space since it was the twelfth anniversary of one of the most challenging and complex construction projects ever attempted by humans away from our planet: The construction of the International Space Stations. On November 20, 1998, the Zarya Control Module was launched. With this simple, almost unnoticed launch in the science community, the construction of a continuously staffed research platform, in Low Earth Orbit, was underway. This paper discusses the research that was performed by many occupants of this research platform during the year celebrating its twelfth anniversary. The main objectives of this paper are fourfold: (1) to discuss the integrated manner in which science planning/replanning and prioritization during the execution phase of an increment is carried out across the United States Orbital Segment since that segment is made of four independent space agencies; (2) to discuss and summarize the research that was performed during increments 16 and 17 (October 2007 to October 2008). The discussion for these two increments is primarily focused on the main objectives of each investigation and its associated hypotheses that were investigated. Whenever available and approved, preliminary research results are also discussed for each of the investigations performed during these two increments; (3) to compare the planned research portfolio for these two increments versus what was actually accomplished during the execution phase in order to discuss the challenges associated with planning and performing research in a space laboratory located over 240 miles up in space, away from the ground support team; (4) to briefly touch on the research portfolio of increments 18 and 19/20 as the International Space Station begins its next decade in Low Earth Orbit. [ABSTRACT FROM AUTHOR]

Abstract: Thermocapillary-driven flow induced in a free thin liquid film under a temperature gradient parallel to the free surfaces is examined with numerical and experimental approaches. Under a small temperature gradient, a two-dimensional flow inside the film is realized in which the fluid returns in the middle region of the film. By increasing the temperature gradient, instability takes place to realize a three-dimensional flow. The authors will introduce a unique flow pattern in the presentation. [Copyright &y& Elsevier]

A study was carried out in a half continuous one incompressible and not viscous, in which the Function of Current thinks about in it anoints sphere, where it is finite and null in the frontier, being obtained the conditions of formation of the spherical Vortex; where the current surfaces are proportional to the fourth power of the vectorial radius, also getting, the principle of dividing current for this case. [ABSTRACT FROM AUTHOR]

Residual-g (gravity) and g-jitter will be unavoidable sources of undesirable convection during diffusion-dominated fluid science or materials science experiments on the International Space Station. In this paper the facility orientation is proposed as an alternative to passive or active isolation devices, which would be not efficient against any residual-g, to minimize g-disturbances during microgravity experiments. A numerical study for a typical fluid physics experiment shows that both residual-g and g-jitter may be detrimental but also beneficial to achieve purely diffusive conditions, according to the orientation of the residual-g vector and of the vibration direction, relative to the direction of the density gradient. The results of the computations indicate that for the different configurations investigated, corresponding to different relative orientations between residual-g and g-jitter, the experimental facility can be properly oriented to minimize the convection disturbances. [ABSTRACT FROM AUTHOR]

It is of great significance to analyze the distribution characteristics of the non-wetting phase during the multiphase flow and identify the positions of the oil ganglia since it can guide us to design the schemes for improving oil recovery. In this paper, the two-phase (brine and oil) flow experiment and simulation are performed on a water-wet sandstone. A comprehensive analysis of the distribution of the non-wetting (oil) phase in 3D pore space and individual pores are presented. To calculate the pore occupancy of the non-wetting ganglia in every single pore from 3D CT experimental data, we proposed a technique, called the Axis-aligned Bounding Box (AABB) algorithm, to determine which oil blobs exist in a unique pore. The pore-by-pore distribution characteristics of the residual phase are then analyzed based on the experimental and numerical data. The results reveal the large oil clusters are separated into small blobs during the imbibition process, which results in increasing the number of non-wetting ganglia, dropping its connectivity, and increasing the smoothness. Moreover, the larger the volume of one pore, the larger the volume and saturation of residual oil ganglia in the pore are. Furthermore, our analysis based on the experimental and numerical results indicates that most of the non-wetting ganglia reside in the median-size pores. Hence, the finding provides us a piece of significant evidence to better target the pore-spaces for the purpose of increasing the recovery. • The pore occupancy of the residual phase in individual pore was analyzed based on the two-phase flow experiment and numerical simulation. • A new technique for analyzing the pore occupancy of residual phase in every single pore from 3D CT experimental images was proposed. • The saturation and the volume of residual oil in one pore can be affected by the volume of the pore. • Waterflooding results in increasing the number of oil ganglia, and dropping the connectivity of the oil phase. • Watrerflooding increases the smoothness of the surface of the oil phase. [ABSTRACT FROM AUTHOR]

The predictor-corrector split-step Fourier method (SSFM) is proposed for solving a nonlinear Schrodinger equation. In comparison with the symmetrized SSFM, the proposed method greatly decreases the relative error and increases the computing speed by ∼2.8 to ∼5.5 times at the same accuracy. [ABSTRACT FROM PUBLISHER]

Survival in aquatic environments requires organisms to have effective means of collecting information from their surroundings through various sensing strategies. In this study, we explore how sensing mode and range depend on body size. We find a hierarchy of sensing modes determined by body size. With increasing body size, a larger battery of modes becomes available (chemosensing, mechanosensing, vision, hearing and echolocation, in that order) while the sensing range also increases. This size-dependent hierarchy and the transitions between primary sensory modes are explained on the grounds of limiting factors set by physiology and the physical laws governing signal generation, transmission and reception. We theoretically predict the body size limits for various sensory modes, which align well with size ranges found in literature. The treatise of all ocean life, from unicellular organisms to whales, demonstrates how body size determines available sensing modes, and thereby acts as a major structuring factor of aquatic life. [ABSTRACT FROM AUTHOR]