Fluid Configurations Research Articles

Reconfiguring Voice in The End: Virtuosity, Technological Affordance and the Reversibility of Hatsune Miku in the Intermundane

AbstractThis article explores the technological affordances of vocal production software in performance through a case study of Shibuya Keīchirō's The End (2012). In the performance of this ‘humanless opera’, desires for pliability and fantasies of control are realised through the affordances of a singing voice synthesis software known as Vocaloid. By reflecting on The End's thematic focus on death and existentialism and on notions of vocal virtuosity, and by exploring the socio-technical processes by which the protagonist, virtual pop star Hatsune Miku, was constructed, the article provides an alternative narrative to vocal production and intermundane collaboration as it relates to the fluid and reversible configurations between voices, bodies and technologies in performance.

Exploring canyons in glassy energy landscapes using metadynamics

The complex physics of glass-forming systems is controlled by the structure of the low-energy portions of their potential energy landscapes. Here we report that a modified metadynamics algorithm efficiently explores and samples low-energy regions of such high-dimensional landscapes. In the energy landscape for a model foam, our algorithm finds and descends meandering canyons in the landscape, which contain dense clusters of energy minima along their floors. Similar canyon structures in the energy landscapes of two model glass formers-hard sphere fluids and the Kob-Andersen glass-allow us to reach high densities and low energies, respectively. In the hard sphere system, fluid configurations are found to form continuous regions that cover the canyon floors up to densities well above the jamming transition. For the Kob-Andersen glass former, our technique samples low-energy states with modest computational effort, with the lowest energies found approaching the predicted Kauzmann limit.

A Review of the Hydraulic Fracturing in Ductile Reservoirs: Theory, Simulation, and Experiment

The bottom-hole pressure of hydraulic fracturing in ductile reservoirs is much higher than that of the hydraulic fracturing simulation, and the fracture toughness inferred from the field data is 1–3 orders of magnitude higher than that measured in the laboratory. The rock apparent fracture toughness increases with the increase in the confining pressure. Excluding the influence of the fluid viscosity and the fluid lag on the apparent fracture toughness, the fracture process zone (FPZ) at the fracture tip can explain the orders of magnitude of difference in the apparent fracture toughness between the laboratory and the field. The fracture tip is passivated by plastic deformation, forming a wide and short hydraulic fracture. However, the size of the FPZ obtained in the laboratory is in the order of centimeters to decimeters, while an FPZ of 10 m magnitude is speculated in the field. The FPZ size is affected by the rock property, grain size, pore fluid, temperature, loading rate, and loading configuration. It is found that the FPZ has a size effect that tends to disappear when the rock specimen size reaches the scale of meters. However, this cannot fully explain the experience of hydraulic fracturing practice. The hydraulic fracturing behavior is also affected by the relation between the fracture toughness and the fracture length. The fracture behavior of type II and mixed type for the ductile rock is poorly understood. At present, the apparent fracture toughness model and the cohesive zone model (CZM) are the most suitable criteria for the fracture propagation in ductile reservoirs, but they cannot fully characterize the influence of the rock plastic deformation on the hydraulic fracturing. The elastic-plastic constitutive model needs to be used to characterize the stress–strain behavior in the hydraulic fracturing simulation, and the fracture propagation criteria suitable for ductile reservoirs also need to be developed.

Pore Space Deformation and Its Implications for Two‐Phase Flow Through Porous Media: A Micro‐Scale Experimental Investigation

AbstractPore space deformation may significantly affect the behavior of multiphase flow through porous media, leading to changes in the effective permeability, relative permeability, and fluid distributions. However, due to the lack of fundamental studies on the mechanisms correlating the pore‐level fluid displacements with the pore space deformation, no compelling conclusions have been reached to account for the observed effects. To explore this correlation, we performed a series of two‐phase (oil/brine) flow experiments on a miniature water‐wet sandpack under various stress conditions, while imaging the pore space and pore fluid configurations using high‐resolution x‐ray microtomography. We investigated the impacts of pore space contraction on the frequency of different pore‐scale fluid displacement mechanisms, as well as the subsequent changes in the fluid saturation and distribution during the drainage and imbibition processes. Variations in the in‐situ capillary pressure with pore space contraction were also examined to further interpret the impacts on fluid displacements. Furthermore, we predicted changes in the relative permeabilities by integrating the end‐point relative permeabilities computed through direct simulations and the end‐point saturations measured from x‐ray images. Our results reveal that the impacts of the pore space deformation on the occupancies of the wetting and non‐wetting phases were distinct. Additionally, the hydraulic conductivity to the wetting phase was more sensitive to the pore space deformation than that to the non‐wetting phase because of their topologically different distributions in the pore space. Consequently, after compression, the relative permeability of the wetting phase decreased, while that of the non‐wetting phase increased.

Effects of thermophysical parameters of fracturing fluid on hot dry rock damage in hydraulic fracturing

Hydraulic fracturing plays a crucial role in the exploitation of hot dry rocks (HDR). However, the effects of the thermophysical parameter of hydraulic fracturing fluid on rock damage mechanism are still not well understood. The study aims at analyzing the influence of thermophysical parameters of fracturing fluid on the damage of HDR through numerical and analytical methods. It is found that the increase of density and specific heat capacity decrease rock damage volume, while the thermal conductivity rises rock damage volume. In addition, the impacts of volume compressions and viscosity on rock damage are not always promoted or inhibited, but change. Liquid permeability is defined in this study, which is found that low liquid permeability results in a larger volume of rock damage. The results would provide guidance for fracturing fluid configuration and hydraulic fracturing process control.

Analysis of charged self-gravitational complex structures evolving quasi-homologously

This paper studies the complex mechanism of evolving charged self-gravitational (dissipating or non-dissipating) systems using a structure scalar [Formula: see text], resulting from the basic procedure of orthogonal decomposition of the Riemann–Christoffel curvature tensor. The influence of electrical charge on the complexity of the considered system is analyzed in detail. We find several analytical Einstein–Maxwell models fulfilling the quasi-homologous [Formula: see text] evolution plus the vanishing complexity factor ([Formula: see text]) condition. Few of the presented models fulfill the Darmois constraints and exhibit shells, however, others satisfy the Israel constraints on both the boundary surfaces. Finally, some possible applications of the presented solutions are mentioned, which are important from astrophysical stand points. It is expected that some of the provided evolving Einstein–Maxwell fluid configurations may be utilized as a toy model of general frameworks like supernova explosions. It is found that the [Formula: see text] implies the vanishing of the [Formula: see text] and gives rise to a unique and simplest configuration (Friedmann–Lemaître–Robertson–Walker model) fulfilling the condition [Formula: see text] and evolving in the [Formula: see text] regime.

Stability Analysis of Isotropic Spheres in Einstein Gauss–Bonnet Gravity

AbstractThis work investigates the effect of electromagnetic field on relativistic compact stellar structures coupled with anisotropic collapsing fluid under the framework of string‐motivated Gauss–Bonnet‐powered gravity. Using the power‐law form of Maxwell‐GB corrections, the stellar structure equations dubbed as Tolman–Oppenheimer–Volkoff (TOV) equations are developed. In the presence of a power‐law form of ‐corrections, an evolution equation for the Weyl scalar is obtained, which plays a central role in the investigation of the examined fluid configuration. It is observed that the existence of shear in the fluid flow, irregularities in the distribution of energy density, dissipative fluxes, and modified Gauss–Bonnet corrections are the certain factors that are accountable for generating anisotropies in an originally isotropic fluid distribution. Some of the interesting consequences of formulated results are examined.

Numerical study on the thermal energy storage employing phase change material with honeycomb structure: The effect of heat transfer fluid configuration and honeycomb cell angles

AbstractConsiderable literature has studied different techniques to improve the thermal performance of latent heat thermal energy systems (LHTES) that utilize phase change materials (PCMs). This study aims to contribute to this growing area of research by using honeycomb structure and exploring the effect of heat transfer fluid (HTF) configuration and honeycomb cell angle on the thermal performance of the LHTES during melting and solidification processes. In this work, five cases were designed: case (a) was regarded as reference case; cases (b) and (c) were related to HTF configuration; cases (d) and (e) were used to study the effect of honeycomb cell angle. A numerical study was conducted using ANSYS FLUENT R19.3, followed by experimental validation. In this study, a good agreement is obtained from the validation process. Computational fluid dynamics (CFD) model results show symmetrical melting and solidification behavior when using a honeycomb structure. The results of the HTF configuration show a significant effect. For case (c) with a multiple water block, significant melting and solidification enhancements are obtained with 56% and 50%, respectively. Thus, the HTF configuration can improve the thermal performance of the storage. However, considering different honeycomb cell angles show an insignificant effect on the melting and solidification rates.

Study of generalized Lemaître–Tolman–Bondi spacetime in Palatini f(R) gravity

The objective of this paper is to investigate the continuation of Lemaître–Tolman–Bondi (LTB) space-time for dissipative dust configuration in the direction of Palatini f(R) theory. In this context, the generalized form of field and dynamical equations will be formulated. We explore the effects of kinematical variables and curvature invariant on our proposed fluid configuration. The significance of Palatini f(R) scalar variables computing through the orthogonal splitting of Riemann-tensor for dissipative dust spheres will be reported. Furthermore, two subcases of LTB space-time have been carried out to note down its symmetric aspects. It is revealed that extended LTB space-time has characteristics comparable to that of LTB and computed scalar variables in both situations have identical dependance on source profile even under the effects of Palatini technique.

Complexity of a dynamical dissipative cylindrical system in non-minimally coupled theory

This paper aims to formulate certain scalar factors associated with the matter variables for a self-gravitating non-static cylindrical geometry by considering a standard model R+ζQ of f(R,T,Q) gravity, where Q=RφϑTφϑ and ζ is the arbitrary coupling parameter. We split the Riemann tensor orthogonally to calculate four scalars and deduce YTF as a complexity factor for the fluid configuration. This scalar incorporates the influence of the inhomogeneous energy density, heat flux and pressure anisotropy along with correction terms for the modified gravity. We discuss the dynamics of the cylinder by considering the two simplest modes of structural evolution. We then take YTF=0 with a homologous condition to determine the solution for the dissipative as well as non-dissipative scenarios. Finally, we discuss the criterion under which the complexity-free condition shows stable behavior throughout the evolution. It is concluded that the complex functional of this theory results in a more complex structure.

Stealth metastable state of scalar-tensor thermodynamics

We investigate a puzzle in the recent thermodynamics of scalar-tensor gravity, in which general relativity is a zero-temperature state of equilibrium and scalar-tensor gravity is the non-equilibrium configuration of an effective dissipative fluid. A stealth solution of Brans-Dicke gravity with constant positive temperature is shown to be analogous to a metastable state for the effective fluid and to suffer from an instability. The stability analysis employs a version of the Bardeen-Ellis-Bruni-Hwang gauge-invariant formalism for cosmological perturbations adapted to modified gravity. The metastable state is destroyed by tensor perturbations.

Self-gravitating anisotropic model in general relativity under modified Van der Waals equation of state: a stable configuration

The purpose of this paper consists in presenting models of compact stars described by a new class of exact solutions to the field equations, in the context of general relativity, for a fluid configuration which is locally anisotropic in the pressure. With current sensitivities, we considered a non-linear form of modified Van der Waals equation of state viz., p_{r}=alpha rho ^{2} +frac{beta rho }{1+gamma rho }, as well as a gravitational potential Z(x) as a generating function by exploiting an anisotropic source of matter which served as a basis for generating the confined compact stars. The exact solutions are formed by correlating an interior space-time geometry to an exterior Schwarzschild vacuum. Then, we analyze the physical viability of the model generated and compare it with observational data of some heavy pulsars coming from the Neutron Star Interior Composition Explorer. The model satisfies all the required pivotal physical and mathematical properties in the compact structures study, offering empirical evidence in support of the evolution of realistic stellar configurations. It is shown to be regular, viable, and stable under the influence generated by the parameters coming from the theory namely, alpha , beta , gamma , delta , everywhere within the astral fluid in the investigated high-density regime that supports the existence of realistic heavy pulsars such as PSR J0348+0432, PSR J0740+6620 and PSR J0030+0451.

Impact of Fluid Dynamics on the Viability and Differentiation Capacity of 3D-Cultured Jaw Periosteal Cells

Perfused bioreactor systems are considered to be a promising approach for the 3D culturing of stem cells by improving the quality of the tissue-engineered grafts in terms of better cell proliferation and deeper penetration of used scaffold materials. Our study aims to establish an optimal perfusion culture system for jaw periosteal cell (JPC)-seeded scaffolds. For this purpose, we used beta-tricalcium phosphate (β-TCP) scaffolds as a three-dimensional structure for cell growth and osteogenic differentiation. Experimental set-ups of tangential and sigmoidal fluid configurations with medium flow rates of 100 and 200 µL/min were applied within the perfusion system. Cell metabolic activities of 3D-cultured JPCs under dynamic conditions with flow rates of 100 and 200 µL/min were increased in the tendency after 1, and 3 days of culture, and were significantly increased after 5 days. Significantly higher cell densities were detected under the four perfused conditions compared to the static condition at day 5. However, cell metabolic and proliferation activity under dynamic conditions showed flow rate independency in our study. In this study, dynamic conditions increased the expression of osteogenic markers (ALPL, COL1A1, RUNX2, and OCN) compared to static conditions and the tangential configuration showed a stronger osteogenic effect than the sigmoidal flow configuration.

Connecting dynamic pore filling mechanisms with equilibrium and out of equilibrium configurations of fluids in nanopores.

In the present study, using dynamic mean field theory complemented by grand canonical molecular dynamics simulations, we investigate the extent to which the density distributions encountered during the dynamics of capillary condensation are related to those distributions at equilibrium or metastable equilibrium in a system at fixed average density (canonical ensemble). We find that the states encountered can be categorized as out of equilibrium or quasi-equilibrium based on the magnitude of the driving force for mass transfer. More specifically, in open-ended slit pores, pore filling via double bridging is an out of equilibrium process, induced by the dynamics of the system, while pore filling by single bridge formation is connected to a series of configurations that are equilibrium configurations in the canonical ensemble and that cannot be observed experimentally by a standard adsorption process, corresponding to the grand canonical ensemble. Likewise, in closed cap slits, the formation of a liquid bridge near the pore opening and its subsequent growth while the initially detached meniscus from the capped end remains immobilized are out of equilibrium processes that occur at large driving forces. On the other hand, at small driving forces, there is a continuous acceleration of the detached meniscus from the capped end, which is associated with complete reversibility in the limit of an infinitesimally small driving force.

Stability analysis of restricted non-static axial geometry in [formula omitted] gravity

The goal of this article is to investigate instability constraints under the influence of f(R,T) gravity in which the Lagrangian is taken as a varying function of Ricci scalar invariant (R) and trace of energy–momentum tensor (T). We examined the stable behavior of axial symmetrical compact fluid configuration with anisotropic conditions. We formulated modified field equations as well as conservation equations in the background of this particular gravity. We constitute the collapse equation, which follows from the perturbation method by applying it to the geometrical and material quantities. A particular f(R,T) gravity model, i.e, f(R,T)=R+αR2+σR+λT is used and perturbed along with conservation and field equations for the systematic analysis. Furthermore, to determine stability criteria of astral configuration, we impose substantial physical conditions in the expression of Γ (i.e., adiabatic index) at Newtonian (N) and post-Newtonian (pN) domains. Also, one can impose constraints on physical entities to establish and maintain its un/stable behavior with the influence of a certain f(R,T) model.

Characterization of Two-Phase Flow from Pore-Scale Imaging Using Fractal Geometry under Water-Wet and Mixed-Wet Conditions

High resolution micro-computed tomography images for multiphase flow provide us an effective tool to understand the mechanism of fluid flow in porous media, which is not only fundamental to the understanding of macroscopic measurements but also for providing benchmark datasets to validate pore-scale modeling. In this study, we start from two datasets of pore scale imaging of two-phase flow obtained experimentally under in situ imaging conditions at different water fractional flows under water-wet and mixed-wet conditions. Then, fractal dimension, lacunarity and succolarity are used to quantify the complexity, clustering and flow capacity of water and oil phases. The results show that with the wettability of rock surface altered from water-wet to mixed-wet, the fractal dimension for the water phase increases while for the oil phase, it decreases obviously at low water saturation. Lacunarity largely depends on the degree of wettability alteration. The more uniform wetting surfaces are distributed, the more homogeneous the fluid configuration is, which indicates smaller values for lacunarity. Moreover, succolarity is shown to well characterize the wettability effect on flow capacity. The succolarity of the oil phase in the water-wet case is larger than that in the mixed-wet case while for the water phase, the succolarity value in the water-wet is small compared with that in the mixed-wet, which show a similar trend with relative permeability curves for water-wet and mixed-wet. Our study provides a perspective into the influence that phase geometry has on relative permeability under controlled wettability and the resulting phase fractal changes under different saturations that occur during multiphase flow, which allows a means to understand phase geometric changes that occur during fluid flow.

Quasi-homologous evolution of relativistic charged objects within [formula omitted] gravity

This paper attempts to explore the evolution of relativistic charged (dissipating or non-dissipating) cosmic objects evolving in quasi-homologous (QH) regime and satisfying the condition of zero complexity factor (CF), under the framework of f(G,T) gravitational theory. For a specific version of f(G,T) theory, various exact solutions for time-dependent charged fluid configurations endowed with spherical symmetry satisfying the above-stated conditions are presented. We will see that few of the provided solutions characterize the evolution of non-static fluid configurations, whose center (r=0) is enclosed by a void. However, some of the modified solutions exhibit shells and fulfill the Israel junction conditions, while others exhibit voids (i.e., they omit the appearance of shells) and fulfill the Darmois matching conditions on both hypersurfaces. Some future applications regarding the presented models in the field of cosmology and relativistic astrophysics are also mentioned.

Retrograde condensation in natural porous media: An in situ experimental investigation

Complex in situ behavior of fluids during a retrograde condensation process is experimentally investigated in a miniature sandstone core sample. Two depletion experiments were conducted with various pressure decline rates using a three-component synthetic gas mixture with a dew point of 3610 psi. A state-of-the-art miniature core-flooding system integrated with a high-resolution micro-computed tomography scanner was employed to acquire pore-scale evidence of condensate nucleation, growth, accumulation, and mobilization in a natural porous medium under different depletion conditions. Analysis of pore-scale fluid occupancy maps demonstrates the formation of discrete nuclei of the condensate in pore throats and crevices as the pressure drops slightly below the dew point. The in situ fluid configurations show that a greater pressure drawdown rate significantly increases the condensate growth and accumulation. The results also illustrate the occurrence of condensate-to-gas imbibition displacements, i.e., snap-off and piston-like events, and the consequent trapping of the gas phase in the pore space. As the pore pressure is reduced, the condensate droplets are found to connect to each other through wetting layers, whereas the large gas clusters are continuously fragmented into smaller globules with reduced hydraulic connectivities. This effect was more pronounced in the case of the high depletion rate experiment. Furthermore, the condensate banking was not completely eliminated (through evaporation) by re-injecting the gas phase. This implies that in the development of a gas condensate reservoir, condensate dropout and banking should be minimized in the first place by, for instance, producing at lower pressure drawdown rates.

Thick toroidal configurations around scalarized Kerr black holes

In this work we aim to investigate thick tori configurations around Kerr black holes with scalar hair (KBHsSH). For that goal, we provide a first approach using constant specific angular momentum non-self-gravitating Polish doughnuts. Through a series of examples, we show the feasibility of new topologies, such as double-centered tori with two cusps as well as similar structures as the ones found for rotating boson stars (BSs), namely, tori endowed with two centers and a single cusp. These KBHsSH solutions are also shown to possibly house static surfaces, associated with the static rings present in these spacetimes. Through this paper we highlight the differences between these fluid configurations when housed by some KBHsSH examples, standard Kerr black holes and rotating BSs.

Two‐Phase Relative Permeability of Rough‐Walled Fractures: A Dynamic Pore‐Scale Modeling of the Effects of Aperture Geometry

AbstractAn accurate description of the relative permeability–saturation function is crucial for reliable predictions of multi‐phase flow behavior in subsurface applications. Although extensive efforts have been put forth to investigate the relative permeability behavior in different types of porous media, only few studies have focused on rough‐walled fractures. In this work, we present an entirely new, cost‐effective, heavily‐parallelized, dynamic pore‐network modeling framework that is employed to conduct a systematic study of relative permeability curves under two‐phase flow conditions in rough‐walled fractures. We first build a two‐dimensional (101.42 × 24.86 mm2) equivalent pore network of a Berea sandstone fracture from its x‐ray images. Subsequently, dynamic primary drainage and imbibition simulations are conducted in the fracture. We show that the two‐phase fluid occupancy maps predicted from the simulations agree well with the fracture fluid configurations obtained via X‐ray computed tomography. Afterward, the validated model is used to probe two‐phase flow properties in a series of synthetic aperture fields generated with a broad range of geometric characteristics including aperture spatial correlation length (normalized correlation length varying from 0.05 to 0.95), anisotropy factor (0.25–4), surface roughness (normalized fracture roughness varying from 0.05 to 0.4), and mean aperture size (50–800 μm). The generated results provide novel insights into the effects of these features on two‐phase flow properties such as fluid–fluid interfacial area, phase interference, and relative permeability. Moreover, based on the simulation results we propose two new correlations to describe the relative permeability curves for primary drainage and imbibition processes in rough‐walled fractures.