Ordinary Fluid Research Articles

Design and experimental investigation of symmetrical embedded magnetic fluid rotary seal with small gap

A novel symmetrical embedded magnetic fluid seal (SEMFS) structure was designed with the aim of enhancing the pressure resistance of the magnetic fluid (MF) seal with small gap under vacuum condition. The magnetic field distribution in the sealing gap (SG) was studied by numerical simulation, and the theoretical pressure resistant-withstanding of the SEMFS was obtained by combining the pressure resistance theories of stepped MFS. An experimental study was conducted to investigate the effects of magnetic fluid injection volume (MFIV), number of pole teeth, SG, and rotational speed of the rotating shaft on the seal's pressure resistance. The pressure resistant-withstanding values obtained were compared with those theoretically projected for the (SEMFS) and the ordinary magnetic fluid seal (OMFS), based on numerical analysis. The results indicate that the measured pressure value for the SEMFS matches well with the calculated pressure value. Furthermore, the SEMFS exhibits superior pressure resistance capabilities compared to the OMFS when subjected to the same parameters, which fully reflects the superiority of SEMFS structure. With an augment in the injection volume of MF, the pressure-withstanding performance of the SEMFS exhibits an initial upward trend followed by a gradual stabilization. Moreover, the pressure-withstanding performance of the SEMFS demonstrates a progressive enhancement with an increase in the number of radial pole teeth (RPT) and a corresponding increment in the number of axial pole teeth (APT). The ability to resist pressure of SEMFS decreases as the radial sealing gap (RSG) and axial sealing gap (ASG) increase. At low shaft speeds, the SEMFS's pressure resistance capability is not impacted by rotational speed and can be considered similar to a static seal.

Dipole superfluid hydrodynamics

We construct a theory of hydrodynamic transport for systems with conserved dipole moment, U(1) charge, energy, and momentum. These models have been considered in the context of fractons, since their elementary and isolated charges are immobile by symmetry, and have two known translation-invariant gapless phases: a “p-wave dipole superfluid” phase where the dipole symmetry is spontaneously broken and a “s-wave dipole superfluid” phase where both the U(1) and dipole symmetries are spontaneously broken. We argue on grounds of symmetry and thermodynamics that there is no transitionally-invariant gapless fluid with unbroken dipole symmetry. In this work, we primarily focus on the hydrodynamic description of p-wave dipole superfluids, including leading dissipative corrections. That theory has, in a sense, a dynamical scaling exponent z = 2, and its spectrum of fluctuations includes novel subdiffusive modes ω ∼ −ik4 in the shear sector and magnon-like sound mode ω ∼ ±k2 − ik2. By coupling the fluid to background fields, we find response functions of the various symmetry currents. We also present a preliminary generalization of our work to s-wave dipole superfluids, which resemble z = 1 fluids and feature sound waves and diffusive shear modes, as in an ordinary fluid. However, the spectrum also contains a magnon-like second-sound mode ω ∼ ±k2 ± k4 − ik4 with subdiffusive attenuation.

Prediction of Viscosity of Cobalt Ferrite/SAE50 Engine Oil based Nanofluids using well Trained Artificial Neutral Network (ANN) and Response Surface Methodology (RSM)

Heat transmission by ordinary fluids such as pure water, oil, and ethylene glycol is inefficient due to their low viscosity. To boost the efficiency of conventional fluids, very small percent of nanoparticles are added to the base fluids to prepare nanofluid. The impact of changing in viscosity can be used to investigate the rheological properties of nanofluids. In this paper, (CoFe2O4)/engine oil based nanofluids were prepared using two steps standard methodology. In first step, CoFe2O4 (CF) were synthesized using the sol-gel wet chemical process. The crystalline structure and morphology were confirmed using X-Ray diffraction analysis (XRD) and scanning electron microscopy (SEM), respectively. In second step, the standard procedure was adapted by taking several solid volume fractions of CF as Ø = 0, 0.25, 0.50, 0.75, and 1.0 %. Such percent of concentrations were dispersed in appropriate volume of engine oil using the ultrasonication for 5 h. After date, the viscosity of prepared five different nanofluids were determined at temperatures ranging from 40 to 80 °C. According to the findings, the viscosity of nanofluids (µnf) decreased as temperature increased while increased when the volume percentage of nanofluids Ø raised. Furthermore, total 25 experimental observations were considered to predict viscosity using an artificial neural network (ANN) and response surface methodology (RSM). The algorithm for building the ideal ANN architecture has been recommended in order to predict the fluid velocity of the CF/SAE-50 oil based nanofluid using MATLAB software. In order to determine the correctness of the predicted model, the mean square error (MSE) was calculated 0.0136.

Numerical and experimental study of the ultimate pressure and self-repairing capability of diverging magnetic fluid seal with stepped pole pieces

With the objective of enhancing the performance of magnetic fluid seal in scenarios with large clearance, an innovative design of a diverging magnetic fluid seal with stepped pole piece has been developed. In contrast to the ordinary magnetic fluid seal, this new seal has advantages such as simple structure and high ultimate pressure. This study investigated the influence of different sealing gaps, step number and step height on both the ultimate pressure and self-repairing capability of the sealing device. The results indicate that the experimental and theoretical values of the new seals have similar trends, and their ultimate pressure and self-repairing capability are closely related to these parameters. These findings confirm the excellent sealing performance of the sealing device.

Study on Gas Adsorption-Desorption and Diffusion Behaviour in Coal Pores Modified by Nano Fracturing Fluid.

Nanoparticles are added to clean fracturing fluids to formulate nanoparticle-modified clean fracturing fluids, compared with ordinary clean fracturing fluid, it has the advantages of good temperature resistance, low loss of filtration, and so forth, and has good application prospects in coal-bed methane. However, the current research on nanoparticle-modified clean fracturing fluids is mostly focused on the study of their rheological properties. The mechanism of nano-fracking fluid influence on methane adsorption-desorption characteristics is not clear. Therefore, this study chooses Jiulishan anthracite coal (high-rank coal), Pingdingshan coal (medium-rank coal), and Geng village mine long bituminous coal (low-rank coal) of the three rank coal samples. Using indoor experiments and molecular simulation methods, a study on the influence of methane adsorption and desorption capacity and diffusion ability of coal samples provides a modified fracturing fluid formulation of 0.8% CATB + 0.2% NaSal + 1% KCl + SiO2. The experimental results show that nanofracturing fluid-treated coal samples compared to clean fracturing fluid treated coal samples, both methane adsorption and desorption capacities, were increased to some extent. Construction of methane adsorption systems with different apertures and calculation of isosteric heat of adsorption, indicating that the interaction force between methane and coal molecules is smaller after nanofracturing fluid treatment, which facilitated methane desorption. A simulation study of methane diffusion in coal samples treated with two systems of fracturing fluids at different aperture was carried out using molecular dynamics methods, indicating that nanoparticle-modified clean fracturing fluids can reduce the damage of clean fracturing fluids to the desorption-diffusion ability of coal reservoirs. Comparison of 6 MPa as the most suitable pressure for nanofracturing fluids to function provides a basis for the future development of nanofracturing fluids and their popularization.

Efekty lepkosprężyste w warunkach nawadniania kolektora szczelinowo-porowego cieczą wodno-polimerową

The work is devoted to the numerical simulation of the flow of simple and viscoelastic (polymer solution) fluids through a fracture by using polymer solutions for enhanced oil recovery from a reservoir. Polymer solutions have viscoelastic properties. Therefore, when polymer solution flows through the slot, we use the well-known Maxwell’s fluid model with the Jaumann derivative to evaluate deformation characteristics of the flow (stream functions, distributions of the longitudinal velocity gradient and normal stress) resulting in the manifestation of abnormal (compared with the behaviour of the ordinary fluid) effects. The case of slow flow is considered. In this case, the inertial terms can be neglected, the velocities, stresses, and stream functions can be written as the decomposition by Weisenberg number, and we can assume that the Weissenberg number is less than one. The determined regularities of viscoelastic (polymer solution) liquid behaviour with longitudinal velocity gradient and the elastic deformations effects manifested in this case have a decisive meaning in understanding the mechanism of anomalously high oil recovery capacity of a reservoir by using water-polymer flooding of the fractured-porous reservoir. Understanding the nature of the effects of elastic deformations under the conditions of water-polymer flooding of the fractured-porous reservoir enables hydrodynamic calculations of the optimal flow of the polymer solution. One of the main issues that need to be solved when developing the technology for increasing oil recovery from formations using polymer solutions is to determine the optimal flow regime in the fractured-porous reservoir. The calculation results verify the ideas obtained from the experimental solution of this problem concerning the strain-stress state of polymer macromolecules (liquid elements) during polymer flow in the inlet area of the fracture in the oil reservoir and confirm the possibility of using numerical analysis of convergent polymer flow for calculating longitudinal velocity gradients in the inlet area of the fracture and can also serve as additional substantiation of the proposed earlier mechanism for increasing oil recovery from reservoirs by using polymer solutions.

Numerical analysis of MHD tri-hybrid nanofluid over a nonlinear stretching/shrinking sheet with heat generation/absorption and slip conditions

In light of the exciting potential of nanofluids, this work presents a new mathematical model for enhancing heat transfer using tri-hybrid nanofluids. In this study, the influence of heat production/abstraction and mass suction on MHD stagnation point flow in a nonlinearly stretching/shrinking sheet of a tri-hybrid nanofluid based on water is investigated. Boundary conditions based on the Maxwell velocity slip and the Smoluchowski temperature are also considered. We shall model the flow-control equations based on our assumptions. An ordinary differential equation system may be constructed from nonlinear partial differential equations for which a similarity transformation does not provide an exact solution. In MATHEMATICA 10, the shooting with Runge-Kutta (RK-IV) technique will be used to solve the reduced equations analytically. There were charts and figures showing how different variables affected the speeds of motion, temperature, skin friction coefficient, and local heat transmission. The characteristics of volume fraction, mass suction, magnetic field, and stretching all contribute to the acceleration of nanoparticles. When the nanoparticle volume fraction and heat production parameters increase, the temperature profile improves, but the mass suction, magnetic, and stretching parameters decrease. Compared to ordinary fluid, the Nusselt number reveals an improvement of around 9.8% for nanofluid, 19.85% for hybrid nanofluid, and 44.04% for tri-hybrid nanofluid when the strength of S is raised from 2.0 to 2.4. The heat transfer rate of the tri-hybrid nanofluid is also superior to that of the hybrid nanofluid and the traditional nanofluid. Results from this study were compared to those already in the literature, and they were determined to be quite consistent. Many other fields might benefit from this study, including those dealing with extreme heat or cold, aerospace technology, medicine, metal coatings, and biosensors.

Flow inspection of micropolar nanofluids with motile gyrotactic microorganisms across symmetric channel in porous medium by quasi-linearization technique

The current article investigates the influence of radiation as well as gyrotactic microbes in the flow of micropolar nanoliquids through a channel. Flow is assumed to be symmetric across a channel having permeable walls. The work also focuses on the change in mass transport rate and density distribution of motile microbes across flow regimes in a porous channel. The governing nonlinear partial differential equations of the present problem are transformed into ODEs through dimensionless variables. The coupled nonlinear ODEs are numerically addressed by utilizing the quasi-linearization technique. Impacts of the pertinent parameters on the fluid flow are analyzed and demonstrated through tables as well as figures by using the powerful tool MATLAB. The velocity profiles escalate near both walls with an enhancement in Reynolds number. Moreover, an enhancement in values of heat radiation parameter causes declination in the fluid temperature. An evaluation of the comparison with existing results reveals an excellent harmony. The nanofluids possess marvelous characteristics subject to heat transport as compared to other ordinary fluids. We intend to elaborate the interaction of micropolar nanofluids with the microbes in a symmetric channel flow.

Convection in a Compressible Rotating Viscoelastic Fluid

The aim of the present work was to study the thermosolutal convection in a compressible rotatory Rivlin-Ericksen viscoelastic fluid in permeable media. Following linear stability theory and normal mode analysis method, the dispersion relation is obtained. For the case of stationary convection, the Rivlin-Ericksen viscoelastic fluid behaves like an ordinary Newtonian fluid. The compressibility, stable solute gradient and rotation are found to postpone the onset of convection, whereas medium permeability hastens or postpones the onset of convection for the case of stationary convection. Also it is found that the system is stable for and under the condition , the system becomes unstable. The case of overstability has also been considered wherein sufficient conditions for the non-existence of overstability are obtained. The stable solute gradient and rotation are found to introduce oscillatory modes in the system.

How Different Connections in Flat FLRW Geometry Impact Energy Conditions in f(Q)$f(Q)$ Theory?

AbstractIn this study of the modified theory of gravity in the spatially flat Friedmann–Lemaître–Robertson–Walker (FLRW) spacetime, all the affine connections compatible with the symmetric teleparallel structure are explored; three classes of such connections exist, each involving an unknown time‐varying parameter . Assuming ordinary barotropic fluid as the matter source, the Friedmann‐like pressure and energy equations are derived. Next constraints on the parameters of two separate models, and from the traditional energy conditions are imposed. Observational values of some prominent cosmological parameters are used for this purpose, yielding an effective equation of state .

Nonlinear convection unsteady flow of electro-magnetohydrodynamic Sutterby hybrid nanofluid in the stagnation zone of a spinning sphere

The heat transfer characteristics of Sutterby hybridized nanofluid flow around a spinning sphere in electro-magnetohydrodynamic nonlinear convective unsteady stagnation point flow are investigated under the influence of convective heating circumstances and quadratic thermal radiation flux. Initially, the AA7072/methanol nanofluid is created by dispersing AA7072 nanoparticles into the methanol. The suitable AA7072+AA7075/ methanol hybrid nanofluid is then created by mixing AA7075 with AA7072/methanol. The governing equations are initially built as partial differential equations, which are subsequently converted to ordinary differential equations by using a similarity transmutation technique. In the study, the numerical technique of the bvp4c solver in Matlab is used. Physical factors’ effects on temperature, concentration, and primary and secondary velocity profiles have been studied. As a result of greater unsteadiness, the magnetic field, and Sutterby fluid parameters, the flow of AA7072/methanol nanofluid and (AA7072+AA7075)/ methanol hybrid nanofluid in the flow region moves quickly in the primary direction and slowly in the rotating direction. The result also demonstrates that a rise in the thermal radiation constraint, temperature ratio parameter, magnetic field constraint, electric field constraint, ϕAA7072, and ϕAA7075 causes a rise in the temperature distribution of the (AA7072+AA7075)/methanol hybrid nanofluid and the AA7072/methanol nanofluid. Furthermore, the strongest enhancement in heat transmission rate happens at a volumetric fraction of 4% of (AA7072+AA7075) nanoparticles and AA7072 nanoparticles (i.e., increased by 5.135827% and 4.370679% when compared with ordinary fluid, respectively). The findings of the study have implications for nano-coating spin processing in the chemical engineering industry, spray applications of agricultural chemicals, drag reducers in pipe flows, and the production of domestic cleaning products.

Goldstone bosons and fluctuating hydrodynamics with dipole and momentum conservation

We develop a Schwinger-Keldysh effective field theory describing the hydrodynamics of a fluid with conserved charge and dipole moments, together with conserved momentum. The resulting hydrodynamic modes are highly unusual, including sound waves with quadratic (magnon-like) dispersion relation and subdiffusive decay rate. Hydrodynamics itself is unstable below four spatial dimensions. We show that the momentum density is, at leading order, the Goldstone boson for a dipole symmetry which appears spontaneously broken at finite charge density. Unlike an ordinary fluid, the presence or absence of energy conservation qualitatively changes the decay rates of the hydrodynamic modes. This effective field theory naturally couples to curved spacetime and background gauge fields; in the flat spacetime limit, we reproduce the “mixed rank tensor fields” previously coupled to fracton matter.

Heat and Mass Transfer, and Chaotic Convection in Nanofluids

The regular and chaotic convection in top-heavy and bottom-heavy Boussinesq nanofluid confined between two horizontal layers heated underneath is investigated. A five-dimensional Lorenz like nonlinear model is obtained using Galerkin technique. This 5-D model possesses two major characteristics viz reflection symmetry and dissipation. The bifurcation diagrams and the phase portraits are used to analyse the characteristics of the dynamical system. The onset of chaos in ordinary fluid, nanofluid bottom-heavy, and nanofluid top-heavy configurations take place at scaled Rayleigh number (R) equals 24.73684211, 26.98908141, and 32.24788322 respectively. The case of ordinary fluids has also been deduced from the five-dimensional model. Weakly nonlinear analysis is also done in order to understand the heat and mass transport inside the system with the variation of scaled Rayleigh number. It is observed that the convection starts earlier in case of top-heavy configuration of nanofluid while gets delayed in bottom-heavy configuration as compared to an ordinary fluid. Moreover onset of chaos gets delayed in case of nanofluids. Another major finding of the study is that the system turns chaotic for higher values of scaled Rayleigh number in the top-heavy case as compared to that of in the bottom-heavy case of nanofluid.

Parametric simulation of hybrid nanofluid flow consisting of cobalt ferrite nanoparticles with second-order slip and variable viscosity over an extending surface

Abstract This study explores the unsteady hybrid nanofluid (NF) flow consisting of cobalt ferrite (CoFe2O4) and copper (Cu) nano particulates with natural convection flow due to an expanding surface implanted in a porous medium. The Cu and CoFe2O4 nanoparticles (NPs) are added to the base fluid water to synthesize the hybrid NF. The effects of second-order velocity slip condition, chemical reaction, heat absorption/generation, temperature-dependent viscosity, and Darcy Forchheimer are also assessed in the present analysis. An ordinary differential equation system is substituted for the modeled equations of the problem. Further computational processing of the differential equations is performed using the parametric continuation method. A validation and accuracy comparison are performed with the Matlab package BVP4C. Physical constraints are used for presenting and reviewing the outcomes. With the increase in second-order velocity slip condition and unsteady viscosity, the rates of heat and mass transition increase significantly with the variation in Cu and Fe2O4 NPs. The findings suggest that the uses of Cu and Fe2O4 in ordinary fluids might be useful in the aerodynamic extrusion of plastic sheets and extrusion of a polymer sheet from a dye.

Experimental investigation on the critical pressure and self-repairing capability of converging magnetic fluid seal with stepped pole pieces

A new design of converging magnetic fluid seal with stepped pole pieces is presented. The new seal has advantages over the traditional magnetic fluid seal, notably simple processing and reduced manufacturing costs. Experimental research is conducted on the new seal's critical pressure and self-repairing capability for different steps, step heights, and radial and axial sealing clearance. Results demonstrate that the theoretical and experimental critical pressure of the new seal is in excellent agreement, the critical pressure and self-repairing capability of the new seal are closely related to the number and height of steps and the sealing clearance. Furthermore, the new seal is found to exhibit superior sealing performance compared with the ordinary magnetic fluid seal.

Odd Mobility of a Passive Tracer in a Chiral Active Fluid.

Chiral active fluids break both time-reversal and parity symmetry, leading to exotic transport phenomena unobservable in ordinary passive fluids. We develop a generalized Green-Kubo relation for the anomalous lift experienced by a passive tracer suspended in a two-dimensional chiral active fluid subjected to an applied force. This anomalous lift is characterized by a transport coefficient termed the odd mobility. We validate our generalized response theory using molecular dynamics simulations, and we show that the asymmetric tracer mobility may be understood mechanically in terms of asymmetric deformations of the tracer-fluid density distribution function. We show that the even and odd components of the mobility decay at different rates with tracer size, suggesting the possibility of size-based particle separation using a chiral active working fluid.

Linear and Quadratic Radiation of Dynamical Non-Fourier Flux in a Disk Flow with the Suspension of Hybrid Nanoparticles

Considering putting in diverse nanoparticles to the base fluid is the latest technique to increase the thermal accomplishment of ordinary fluids. for the present investigation, the flow and heat transfer of nanofluids over a spinning disk with an invariable stretching pace is observed. The non-Fourier flux, magnetic field, and radian heat have all been paid regard to. The nanoparticle used here is Graphene with water as a base fluid. The governing equations are reshaped by utilizing Von Karman transformation and worked it out numerically via boundary value problem solver (bvp5c). We also provided some of the results with magnetic field and beside magnetic field cases and found disparity in both circumstances. Results pointed out that with little proliferation in stretching force constant, the skin friction and the local Nusselt number, the velocity in radial and axial paths improved, when the velocity in the tangential trend and the thermal boundary layer thickness reduce, significantly.

Thermal performance analysis of magnetized convectively heated ferromagnetic nanoparticles for radiative cross nanofluid flow

The main purpose of this work is to investigate the innovation of flow of two-dimensional (2D) ferrofluid flow passing upon stretched surface having the effect of a magnetic dipole. The said problem is selected since its use is very common in biomedical as well as engineering applications together with systems of drug targeting under magnetic effects. The impacts of magnetic dipole along with radiation parameter in flow of ferromagnetic cross fluid for a stretched region are investigated in detail by use of suitable similarity variables the nonlinear, ODEs are obtained. The desired ODEs are resolved numerically by using RK fifth-order method parallel to shooting scheme. Impacts of ferromagnetic interaction, viscous dissipation, Curie temperature, and Buongiorno parameters with convective boundary conditions are perceived for velocity, temperature and concentration fields. Furthermore, the terms like velocity, mass transfer and thermal gradients are under consideration and pictorial scrutinizing is done. Moreover, temperature of ferromagnetic fluid upsurges for enlargement in the values of ferrohydrodynamics interaction and Curie temperature parameters. Concentration of ferrofluid reveals a contrary tendency against the parameters of thermophoresis and Brownian motion. Owing to extensive application prospects of magnetized nanofluids, this area has received interest from engineers and researchers; nanofluids have a noteworthy preference over ordinary fluids.

Irreversibility analysis of electromagnetic hybrid nanofluid for Cattaneo–Christov heat flux model using finite element approach

To get a better heat transmission capacity of ordinary fluids, new hybrid nanofluids (HNFs) with a considerably greater exponent heat than nanofluids (NFs) are being used. HNFs, which have a greater heat exponent than NFs, are being applied to increase the HT capacities of regular fluids. Two-element nanoparticles mixed in a base fluid make up HNFs. This research investigates the flow and HT features of HNF across a slick surface. As a result, the geometric model is explained by employing symmetry. The technique includes nanoparticles shape factor, Magnetohydrodynamics (MHD), porous media, Cattaneo–Christov, and thermal radiative heat flux effects. The governing equations are numerically solved by consuming a method known as the Galerkin finite element method (FEM). In this study, H2O-water was utilized as an ironic, viscous improper fluid, and HNF was investigated. Copper (Co) and Titanium Alloy (Ti6Al4V) nanoparticles are found in this fluid. The HT level of such a fluid (Ti6Al4V-Co/H2O) has steadily increased in comparison to ordinary Co-H2O NFs, which is a significant discovery from this work. The inclusion of nanoparticles aids in the stabilization of a nanofluid flowing and maintains the symmetry of the flow form. The thermal conductivity is highest in the boundary-lamina-shaped layer and lowest in sphere-shaped nanoparticles. A system's entropy increases by three characteristics: their ratio by fractional size, their radiated qualities, and their heat conductivity modifications. The primary applications of this examination are the biological and medical implementations like dental and orthopedic implantable devices, as well as other devices such as screws and plates because they possess a favorable set of characteristics such as good biomaterials, corrosion resistance and wear, and great mechanical characteristics.

Optimization of MHD Flow of Radiative Micropolar Nanofluid in a Channel by RSM: Sensitivity Analysis

These days, heat transfer plays a significant role in the fields of engineering and energy, particularly in the biological sciences. Ordinary fluid is inadequate to transfer heat in an efficient manner, therefore, several models were considered for the betterment of heat transfer. One of the most prominent models is a single-phase nanofluid model. The present study is devoted to solving the problem of micropolar fluid with a single-phase model in a channel numerically. The governing partial differential equations (PDEs) are converted into nonlinear ordinary differential equations (ODEs) by introducing similarity transformation and then solved numerically by the finite difference method. Response surface methodology (RSM) together with sensitivity analysis are implemented for the optimization analysis. The study reveals that sensitivity of the skin friction coefficient (Cfx) to the Reynolds number (R) and magnetic parameter (M) is positive (directly proportional) and negative (inversely proportional) for the micropolar parameter.