Hypothetical Fluid Research Articles

Tidal Heating in a Subsurface Magma Ocean on Io Revisited

AbstractWe investigate the tidal dissipation in Io's hypothetical fluid magma ocean using a new approach based on the solution of the 3D Navier‐Stokes equations. Our results indicate that the presence of a shallow magma ocean on top of a solid, partially molten layer leads to an order of magnitude increase in dissipation at low latitudes. Tidal heating in Io's magma ocean does not correlate with the distribution of hot spots, and is maximum for an ocean thickness of about 1 km and a viscosity of less than 104 Pa s. Due to the Coriolis effect, the k2 Love number can depend on the harmonic order. We show that the analysis of k2 may not reveal the presence of a fluid magma ocean if the ocean thickness is less than 2 km. If the fluid layer is thicker than 2 km, k20 ≈ k22/2 ≈ 0.7.

Flow fields of a non-Newtonian fluid in vortex chamber pumps

Problem. Pumping different fluids by hydraulic transport is associated with fast wear of the pump contact surfaces. The fluids being pumped are often non-Newtonian. The use of jet pumps for pumping is impractical due to low efficiency. Vortex chamber pumps may have higher efficiency when pumping non-Newtonian fluids, however, their operation on such fluids has not yet been studied. The aim of this work is to study the characteristics of the flow fields of a non-Newtonian fluid using the example of a Bingham fluid in the vortex chamber pump. Methodology. Predicting pump energy performance and determining flow fields for highly viscous fluids using CFD simulations enables advanced jet pumps to handle non-Newtonian fluids. Results. Modeling was carried out based on the numerical solution of the RANS equations with the SST turbulence model. To ensure the operability of the vortex chamber pump when pumping non-Newtonian fluid, with known rheological parameters of the mixture, it is necessary to select the required supply pressure for the active flow, and also to consider the issue of diluting the liquid with water to reduce the mixture viscosity and achieve the specified values of the pumping energy parameters. Originality. The hypothesis that the vortex chamber supercharger can operate on a hypothetical ideal fluid has been confirmed. In this case, the performance indicators of such a supercharger improve and tend to ideal. With an increase in plastic viscosity, the volumetric flow rate of the pumped fluid decreases, and at high values of the viscosity, an active flow is ejected through the axial channels. Practical value. Researchers can use the theoretical results of this work to design new devices for pumping other Bingham fluids, such as oil paint, resins, varnishes, swamp soils, and many others.

Synthesis, Characterization, and Drug Release Study of Modified Chitosan

This research included loading of drugs (ibuprofen, ketoprofen, and fenoprofen) on a chitosan polymer to produce drug-loading polymer by entering the chitosan in a Schiff base reaction to protect -NH2 group, the reacting of the product with drug chloride. The prepared compounds were identified spectroscopically, by using infrared spectroscopy, 1H-NMR, and 13C-NMR. The thermal stability of chitosan was measured by using differential scanning calorimeter (DSC) and Differential thermal analysis (DTA). The drug release of ibuprofen, ketoprofen, and fenoprofen from chitosan in hypothetical stomach fluid was studied. The drug concentration that was released in stomach fluid several times was determined by measuring the absorbance in ultraviolet (UV) spectroscopy.

Posing constraints on the free parameters of a new model of dark energy EoS: responses through cosmological behaviours

Since the late 1990's observations of type Ia Supernova, our universe is predicted to experience a late time cosmic acceleration. Theoretical support to this observation were intended to be built via proposition of a hypothetical fluid which staying inside the universe exerts negative pressure. Cosmologists have prescribed many candidates for this exotic fluid so far. In this alley, a popular method is to choose time dependent equation of state parameter $\omega = \frac{p}{\rho}$ and to parametrize it as a function of redshift. Again some common families of such parametrizations are constructed among which different members justify different properties of observed universe. Mainly, these were model dependent studies which comprise free parameters to be constrained by different observations. In this present article, a new expression for redshift parametrization is considered and we have constrain its free parameters for two Hubble parameter vs redshift data sets. These data sets are obtained depending on two basic methodologies known as different ages method and baryonic acoustic oscillation method. Different confidence contours for our model are located under the constraints of said data sets. Besides, different thermodynamic parameters related to the evolution of our universe are analysed. It is notified that our model indicates towards a delayed dark matter model which mimics EoS = $-1(\Lambda)$ phenomena at the present epoch. Deceleration parameters behaviour's are studied. It is noticed that a possibility of future deceleration may occur for this new model. Outcomes for both the data sets are compared with each other.

Inflation in the Rényi cosmology

The description of the accelerated phases for the current and primordial cosmos has been obtained in the framework of Rényi cosmology. The results show that corrections to the Friedmann equations, originated from differences between Rényi and Bekenstein entropies, can describe both the current accelerated and inflationary eras. The effects of these corrections can be appointed to a hypothetical fluid which is classically unstable. Although inflation can be obtained in Rényi cosmology as the vacuum solution, the values found for the parameters of the hypothetical fluid which supports the current accelerated and primary inflationary cosmos differ from each other.

Realizing interactions between dark matter and dark energy using k-essence cosmology

In this paper, we exploit dynamics of a [Formula: see text]-essence scalar field to realize interactions between dark components of universe resulting in an evolution consistent with observed features of late-time phase of cosmic evolution. Stress–energy tensor corresponding to a [Formula: see text]-essence Lagrangian [Formula: see text] (where [Formula: see text]) is shown to be equivalent to an ideal fluid with two components having same equation of state. Stress–energy tensor of one of the components may be generated from a constant potential [Formula: see text]-essence Lagrangian of form [Formula: see text] ([Formula: see text] constant) and that of other from another Lagrangian of form [Formula: see text] with [Formula: see text]. We have shown that the unified dynamics of dark matter and dark energy described by a single scalar field [Formula: see text] driven by a [Formula: see text]-essence Lagrangian [Formula: see text] may be viewed in terms of diffusive interactions between the two hypothetical fluid components “1” and “2” with stress–energy tensors equivalent to that of Lagrangians [Formula: see text] and [Formula: see text], respectively. The energy transfer between the fluid components is determined by functions [Formula: see text], [Formula: see text] and their derivatives. Such a realization is shown to be consistent with the Supernova Ia data with certain constraints on the temporal behavior of [Formula: see text]-essence potential [Formula: see text]. We have described a methodology to obtain such constraints.

Effective viscosity of a concentrated suspension of composite porous spherical particles

We present an analytical study of the effective viscosity of concentrated suspension of porous spherical particles with a rigid core, under the creeping flow conditions. It is assumed that the individual particle is surrounded by a hypothetical fluid envelope. This model is popularly known as cell model, which takes into account the interaction of neighboring particles. The flow fields inside the free flow region and porous region are governed by Stokes equation and Brinkman equation together with mass conservation, respectively. The effective viscosity of the suspension depends on various parameters such as, radii of the fluid envelope and porous particle, permeability of the porous particle and further on the type of boundary condition at the outer cell, volume fraction etc. Various limiting cases are obtained and compared with earlier existing results in literature both theoretical and experimental.

Pumped heat electricity storage: potential analysis and orc requirements

The rising share of renewable energy sources in power generation leads to the need of energy storage capacities. In this context, also some interest in thermal energy storages, especially in a concept called pumped heat electricity storage (PHES), arises. One possible design of such a PHES system consists of a compression heat pump, a thermal storage and an organic Rankine cycle (ORC). The present work analyses the general thermodynamic potential and limits of such a system and deals with the unusual requirements for the ORC. The potential analysis starts with the optimal case of combining two Carnot cycles with irreversible heat transfer. It is found that the efficiency of the entire process increases with increasing storage temperature and in general roundtrip efficiencies up to 70 % are predicted. Afterwards the cycles are transferred to cycles that are more realistic by considering technical aspects and a hypothetical working fluid which is optimized by an inverse engineering approach. This leads to lowered roundtrip efficiencies, which now, decrease with increasing storage temperatures. In a second step the specific ORC requirements as part of a PHES are considered, emphasizing the working fluid parameters. Especially, the use of a latent thermal energy storage leads to an ORC design differing from common (e.g. geothermal) applications. It is shown that the efficiency of the ORC and of the entire process strongly depends on the superheating at the expander inlet; here, the superheating must be held as small as possible, contrary to ORCs using common heat sources.

Integrated design of ORC process and working fluid using PC-SAFT and Modelica

Organic Rankine Cycles (ORC) use low-temperature heat to generate electrical power. To use the full potential of a heat source, the ORC has to be tailored to the specific application. Tailoring a cycle means an integrated design of both process and working fluid. This integrated design leads to complex mixed-integer nonlinear program (MINLP) optimization problems. To avoid this complexity, working fluid candidates are commonly preselected using heuristic guidelines; subsequently, the process is optimized for the set of preselected working fluids. However, the preselection can fail, leading to suboptimal solutions.An approach for integrated design of ORC process and working fluid is the Continuous-Molecular Targeting–Computer-aided Molecular Design (CoMT-CAMD) approach. CoMT-CAMD employs the physically-based Perturbed-chain Statistical Associating Fluid Theory (PC-SAFT) equation of state as thermodynamic model of the working fluid. In PC-SAFT, each working fluid is described by a set of pure component parameters. In a first step, the so-called CoMT step, the discrete pure component parameters are relaxed resulting in a hypothetical optimal working fluid and the corresponding optimal process. In a second step, real working fluids with similar properties are identified using Computer-aided Molecular Design and a second-order Taylor approximation of the objective function around the hypothetical optimum. So far, the process models in CoMT-CAMD were implemented in a procedural programming language, which hinders the reusability, the use for more complex processes and dynamic simulations.In this work, we integrate CoMT-CAMD into the object-oriented modelling language Modelica. For this purpose, Modelica is directly linked to PC-SAFT. Thereby, already existing model libraries for Modelica can be used to model the ORC process. The resulting design approach is applied to the integrated design of an ORC process and working fluid for a geothermal power station.

Hydrothermal system of the Kirishima volcanic area inferred from the chemical and isotopic composition of spring waters and fumarolic gases

The chemical and isotopic composition of hot spring waters and fumarolic gases from the Kirishima volcanic area were investigated in order to delineate the geochemical structure of the hydrothermal systems. There are active volcanoes, Iwoyama, Shinmoe and Ohachi locate in the area, and each of them has characteristic hydrothermal systems. At Iwoyama volcano, chloride-sulfate type waters are discharging from central part, and acid sulfate type waters are located on its north and west flanks. On the south west flank of Shinmoe volcano, CO 2 type waters are located. At a deep part on the west Sank of both volcanoes chloride type waters are distributed. This variety of different type of waters can be derived from differentiations of a hypothetical parent fluid. The chloride type water seems to be a liquid phase separated from the mixture of the parental fluid and ground water. The vapor phase separated from the liquid phase heats ground water and produces the sulfate type and the CO 2 type waters. In the hydrothermal systems beneath Iwoyama volcano, a parental fluid is differentiated to a chloride-sulfate type water and a H 2 S rich fumarolic gas. The parent fluid in the hydrothermal system of Shinmoe volcano seems to be depleted in sulfur species than the parental fluid for Iwoyama. Ohachi volcano has a faint fumarolic activity at the summit. The fumarolic gas losses most of water vapor prior to the discharge due to a conductive cooling and condensation of the vapor up to the summit. A model calculation evaluates the original composition of the fumarolic gas from Ohachi volcano. The original composition resembles to those of the fumarolic gases from the summit of Shinmoe volcano.

The Interface Between Fresh and Salt Groundwater in Horizontal Aquifers: The Dupuit\u2013Forchheimer Approximation Revisited

We analyze the motion of a sharp interface between fresh and salt groundwater in horizontal, confined aquifers of infinite extend. The analysis is based on earlier results of De Josselin de Jong (Proc Euromech 143:75–82, 1981). Parameterizing the height of the interface along the horizontal base of the aquifer and assuming the validity of the Dupuit–Forchheimer approximation in both the fresh and saltwater, he derived an approximate interface motion equation. This equation is a nonlinear doubly degenerate diffusion equation in terms of the height of the interface. In that paper, he also developed a stream function-based formulation for the dynamics of a two-fluid interface. By replacing the two fluids by one hypothetical fluid, with a distribution of vortices along the interface, the exact discharge field throughout the flow domain can be determined. Starting point for our analysis is the stream function formulation. We derive an exact integro-differential equation for the movement of the interface. We show that the pointwise differential terms are identical to the approximate Dupuit–Forchheimer interface motion equation as derived by De Josselin de Jong. We analyze (mathematical) properties of the additional integral term in the exact interface motion formulation to validate the approximate Dupuit–Forchheimer interface motion equation. We also consider the case of flat interfaces, and we study the behavior of the toe of the interface. In particular, we give a criterion for finite or infinite speed of propagation.

Application of Highly Accurate Phase-Equilibrium Models for CO2 Freezing Prediction of Natural Gas System

It is of great engineering significance to find an accurate model to predict CO2 freezing and avoid plugging in the light hydrocarbon separation process of natural gas. Research starts from CO2 freezing in simple CH4–CO2 binary systems. By use of a traditional model based on the Antoine equation, the calculated freezing temperature in liquid–solid equilibrium (LSE) is not as accurate as that in vapor–solid equilibrium (VSE). Then a new thermodynamic method of reference state of hypothetical fluid is used to replace LSE model based on the Antoine equation to calculate solid CO2 fugacity. The improved phase-equilibrium model based on GERG-2008 is proved to be the most accurate one to calculate CO2 freezing temperature, in which the Antoine equation is used in VSE model while reference state method is used in LSE model. Compared with experimental data, the calculated results also show a higher accuracy in complex natural gas system. Besides, the improved phase-equilibrium model is applied in the actual light...

Dissipative particle dynamics study and experimental verification on the pore morphologies and diffusivity of the poly (4-methyl-1-pentene)-diluent system via thermally induced phase separation: The effect of diluent and polymer concentration

Dissipative particle dynamics (DPD) simulation was performed to construct the mesophase membrane morphologies of poly(4-methyl-1-pentene) (PMP) during thermally induced phase separation (TIPS). The PMP morphologies and their fluid diffusivities relationship was established using a mesoscale 3-D tetragonal-like structure construction. The effects of PMP concentration and the use of a single diluent (dioctyl phthalate, diphenyl ether, and dibutyl phthalate) or a mixed diluent on the pore morphology were compared. The diffusivity resistance was evaluated by comparing the mean square displacement of a hypothetical fluid bead through tetragonal-like morphologies in three normal directions. The 3-D morphology and density profile results revealed that larger pores were produced after TIPS when the PMP-diluent interaction was weaker. Radial distribution function analysis showed that poor diluent and high PMP concentration could form a coarsened structure with less interconnectivity, indicating more diffusion resistance. To verify DPD simulation results, PMP hollow fibre membranes (HFMs) were fabricated via TIPS, and HFM cross-sectional morphologies proved that the pore structures agreed with the DPD-simulation 3-D evolution diagram. The structure-fluid diffusivity resistance relationship was also confirmed by porosity measurements and gas permeation testing. The DPD simulation method is promising for the fabrication and design of gas-diffusive membranes, especially in terms of the rational selection of diluent and polymer concentration.

Lavoisier’s “Reflections on phlogiston” II: on the nature of heat

Having refuted the phlogiston theory, Lavoisier uses this second portion of his essay to expound his new theory of combustion, based on the oxygen principle. He gives a mechanistic account of thermodynamic phenomena in terms of a subtle fluid (not yet named “caloric”) and its ability to penetrate porous bodies. He uses this hypothetical fluid to explain volume changes, heat capacity and latent heat. Beyond the three types of combustion that he distinguishes and defines, Lavoisier also explains other chemical sources of heat, such as the heat of solution.

Interacting Holographic Dark Energy, Future Singularity and Polytropic Gas Model of Dark Energy in Closed FRW Universe

The present work deals with the accretion of two interacting fluids: dark matter and a hypothetical fluid as the holographic dark energy components onto wormhole in a non-flat FRW universe. First of all, following Cruz et al. (Phys. Lett. B 669, 271 2008), we obtained an exact solution of the Einstein’s field equations. Solution describes effectively the actual acceleration and indicates a big rip type future singularity of the universe. After that we have studied the evolution of the mass of wormhole embedded in this FRW universe in order to reproduce a stable universe protected against future-time singularity. We found that the accretion of these dark components leads to a gradual increase of wormhole mass. It is also observed that contrary to the case as shown by Cruz et al. (Phys. Lett. B 669, 271 2008), the big rip singularity of the universe with a divergent Hubble parameter of this dark energy model may be avoided by a big trip. We have established a correspondence between the holographic dark energy with the polytropic gas dark energy model and obtained the potential as well as dynamics of the scalar field which describes the polytropic cosmology.

Computer-aided molecular design in the continuous-molecular targeting framework using group-contribution PC-SAFT

Computer-aided molecular design allows generating novel fluids fulfilling a set of target properties. An integrated design of fluid and process directly employs a process-based objective function. In this work, we solve the integrated process and fluid design problem using the continuous-molecular targeting computer-aided molecular design (CoMT–CAMD) framework. CoMT–CAMD exploits the molecular picture underlying the PC-SAFT equation of state. In the simultaneous optimization of process and fluid, relaxed pure component parameters allow for an efficient optimization. The result is a hypothetical optimal target fluid. In previous work, fluids showing similar performance as the target fluid were obtained from a mapping onto a database. Here, we integrate computer-aided molecular design to realize the actual design of novel fluids. The resulting method for fluid design is based on a group-contribution method for the PC-SAFT parameters (GPC-SAFT) and applied to the design of working fluids for Organic Rankine cycles and solvents for CO2 capture.

Holographic dark energy with linearly varying deceleration parameter and escaping big rip singularity of the Bianchi type-V universe

The present work deals with the accretion of two minimally interacting fluids: dark matter and a hypothetical isotropic fluid as the holographic dark energy components onto black hole and wormhole in a spatially homogeneous and anisotropic Bianchi type-V universe. To obtain an exact solution of the Einstein’s field equations, we use the assumption of linearly varying deceleration parameter. Solution describes effectively the actual acceleration and indicates a big rip type future singularity of the universe. We have studied the evolution of the mass of black hole and the wormhole embedded in this anisotropic universe in order to reproduce a stable universe protected against future-time singularity. It is observed that the accretion of these dark components leads to a gradual decrease and increase of black hole and wormhole mass respectively. Finally, we have found that contrary to our previous case (Sarkar in Astrophys. Space. Sci. 341:651, 2014a), the big rip singularity of the universe with a divergent Hubble parameter of this dark energy model may be avoided by a big trip.

Interacting holographic dark energy with variable deceleration parameter and accreting black holes in Bianchi type-V universe

In this paper, we have considered the spatially homogeneous and anisotropic Bianchi type-V space time filled with two interacting fluids; dark matter and a hypothetical isotropic fluid as the holographic dark energy components. To obtain an exact solution of the Einstein’s field equations, we used the assumption of time dependent deceleration parameter. We have investigated geometric and kinematic properties of the model. It is observed that the anisotropy parameter of the universe approaches to zero and the universe achieve flatness for large cosmic time. We have shown that this expanding solution is stable against the perturbation with respect to anisotropic spatial directions. We have also studied the evolution of the mass of a black hole embedded in a universe which interacts with a combination of dark matter and dark energy, considering that in the vicinity of the black hole the metric is of Schwarzschild type. We found that the black hole mass increases with the evolution of the universe, and on later epochs the increase in mass stops as dark energy accretion takes over. The results are found to be consistent with recent cosmological observations.

Holographic dark energy model with variable deceleration parameter, cosmic coincidence and the future singularity of the Kantowski-Sachs universe

The present work deals with a spatially homogeneous and anisotropic Kantowski-Sachs space time filled with two minimally interacting fluids; dark matter and a hypothetical anisotropic fluid as the holographic dark energy components. To obtain an exact solution of the Einstein’s field equations, we used the assumption of linearly varying deceleration parameter. We have investigated geometric and kinematic properties of the model and the role of the anisotropic holographic dark energy in the evolution of the Kantowski-Sachs universe. Under the suitable condition, it is observed that the anisotropy parameter of the universe and the skewness parameter of the holographic dark energy approaches to zero for large cosmic time and the universe can achieve flatness for some particular moments throughout its entire lifetime. Results show that the coincidence parameter $( \Re= \frac{\rho_{\varLambda}}{\rho_{M}} )$ increases with increasing time and a big rip type future singularity will occur for this model. We have also applied the statefinder diagnostics method to study the behavior of different stages of the universe and to differentiate the proposed dark energy model from the ΛCDM model. Since in this model, the universe has a finite life time and passes through a significant time when the dark energy and the matter energy densities are roughly comparable, so considering $\frac{1}{ \Re_{0}} <\Re < \Re_{0}$ , where ℜ0 is any fixed ratio, we have calculated the fraction of total life time of the universe when the universe passes through the coincidental stage for this future singularity. The results are found to be consistent with recent cosmological observations.

Anisotropic Dark Energy Bianchi Type-II Cosmological Models in Lyra Geometry

The spatially homogeneous and totally anisotropic Bianchi type-II cosmological model has been discussed in general relativity in the presence of a hypothetical anisotropic dark energy fluid with constant deceleration parameter within the frame work of Lyra’s manifold with uniform and time varying displacement field vector. With the help of special law of variation for Hubble’s parameter proposed by Bermann (Nuovo Cimento 74B:182, 1983) a dark energy cosmological model is obtained in this theory. We use the power law relation between average Hubble parameter H and average scale factor R to find the solution. The assumption of constant deceleration parameter leads to two models of universe, i.e. power law model and exponential model. Some physical and kinematical properties of the model are also discussed.