Flow Of Rotating Fluid Research Articles

Mixed convection hybrid nanofluid flow over a rotating cone in a rotating fluid environment with interfacial nanolayer effect

This study explores the dynamics of a mixed magneto-hybrid nanofluid (HNF) flowing over a rotating cone within a rotational fluid flow, focusing on the effects of joule heating and thermal radiation. Employing water as a base fluid, enhanced with nanoparticles like molybdenum disulfide (MoS2) and graphene oxide (GO), we examine the critical role of liquid–solid interfacial layers on thermal integrity and boundary conditions. The governing model integrates joule heating, thermal radiation, mixed convection, and magnetic effects to fully represent the complexities of the flow dynamics. A system of partial differential equations (PDEs), simplified under boundary layer assumptions, is transformed into ordinary differential equations (ODEs) through similarity transformations. These ODEs are then solved using the Homotopy Analysis Method (HAM) in Mathematica. Notably, our results demonstrate an improvement in heat transfer rates under combined magnetic and rotational influences, compared to conventional fluids. This enhanced cooling efficiency is critical for applications like aeronautical gas turbines and power production turbines, where higher thermal regulation directly correlates with improved performance, durability, and operational efficiency. Moreover, the study reveals a significant sensitivity of the thermal boundary layer to variations in the Prandtl number, indicating that higher Prandtl numbers lead to a lower temperature profile. This finding is vital for optimizing heat transfer processes, particularly in engineering applications where precise control over thermal properties is required. Furthermore, the study provides detailed insights into the friction factors for azimuthal and tangential directions, alongside local Nusselt numbers, offering substantial agreement with prior research. These findings contribute significantly to the design and optimization of modern cooling systems, emphasizing the potential of HNFs in high-temperature environments.

Topology optimization for flow machine rotor design considering resonance and low mass density flows

When designing structures that take part in rotating fluid flow machines, one important effect that may be taken into account is resonance, which is evaluated through the modal analysis. Under rotating conditions, the formulation and behavior of the structure changes, requiring a new formulation. Thus, this work formulates the fluid flow topology optimization for rotating resonance, while also considering a low mass density (compressible or incompressible) fluid flow. Therefore, three different effects are considered in the fluid flow-based design: from the modal analysis, from the solid structure, and from the low mass density fluid flow. The topology optimization problem is formulated for a simplified 2D model of a rotating fluid flow device, and a nodal design variable. The topology optimization is performed through an integer linear programming algorithm. Numerical examples are presented for the developed topology optimization formulation.

Effect of Soret on MHD rotating fluid flow through a porous medium with heat and mass transfer

PurposeThe purpose of this paper to analyze the effect of Soret with heat and mass transfer on an unsteady two-dimensional Magnetohydrodynamics flow through a porous medium under the influence of the uniform transverse magnetic field in a rotating parallel plate is considered.Design/methodology/approachA mathematical model was developed using the slip conditions under unsteady state situations. Analytical expressions for the velocity, temperature and concentration profiles, wall shear stress, rates of heat and mass transfer and volumetric flow rate were obtained and computationally discussed with respect to the non-dimensional parameters. Further, the velocity reduces with increasing Hartmann number M and increases with Grashof number Gr and permeability parameter K.FindingsIt is observed that temperature reduces with an increase in Prandtl number Pr and ω. It is noted that the thermal radiation increases with increase in Soret number Sr, Schmidt number Sc, Prandtl number pr and ω.Originality/valueConcentration decreases with an increase in radiation parameter R and chemical reaction parameter Kc.

Laboratory experiments reveal intrinsic self-sustained oscillations in ocean relevant rotating fluid flows

Several ocean Western Boundary Currents (WBCs) encounter a lateral gap along their path. Examples are the Kuroshio Current penetrating into the South China Sea through the Luzon Strait and the Gulf of Mexico Loop Current leaping from the Yucatan peninsula to Florida as part of the Gulf Stream system. Here, we present results on WBC relevant flows, generated in the world’s largest rotating platform, where the Earth’s sphericity necessary to support WBCs is realized by an equivalent topographic effect. The fluid is put in motion by a pump system, which produces a current that is stationary far from the gap. When the jet reaches the gap entrance, time-dependent patterns with complex spatial structures appear, with the jet leaking, leaping or looping through the gap. The occurrence of these intrinsic self-sustained periodic or aperiodic oscillations depending on current intensity is well known in nonlinear dynamical systems theory and occurs in many real systems. It has been observed here for the first time in real rotating fluid flows and is thought to be highly relevant to explain low-frequency variability in ocean WBCs.

Exploration of radiative heat on magnetohydrodynamic rotating fluid flow through a vertical sheet

AbstractAn analysis is built up for the exploration of radiative heat transport on the magnetohydrodynamic flow of rotating fluid over a vertical sheet. The inclusion of thermal radiation in conjunction with the reacting species enhances the energy as well as the solutal profiles respectively. In an advance, external heat source and applied magnetic field effects are considered for further improvement. As the magnetic Reynolds number is low, the influence of the induced magnetic field is neglected. The transformation of governing nonlinear partial differential equations into coupled nonlinear ordinary differential equations is attained with a proper supposition of similarity variables. Moreover, the solution of these transformed equations is scheduled using the “Runge–Kutta fourth‐order” method numerically in association with the “shooting technique.” The simulation or various illustrating parameters affecting the flow phenomena are obtained and displayed through graphs and for numerical validation with earlier published work shows the convergence process of the methodology applied. The main findings of the study are; the Dufour number is favorable to enhance the fluid temperature throughout the domain and the destructive chemical reaction also encourages the solutal profile significantly.

PF-LBM Modelling of Dendritic Growth and Motion in an Undercooled Melt of Fe-C Binary Alloy

In the present study, a two-dimensional phase field model coupled with Lattice Boltzmann method (PF-LBM) is proposed to predict the dendritic growth and motion in the melt of Fe-C binary alloy, where the phase field method (PF) is used to calculate the dendritic growth, including the phase field and the concentration field, and the lattice Boltzmann method (LBM) is used to calculate the flow field. The dendrite motion is determined by Newton’s Second Law and tracked by Lagrangian point in a Cartesian coordinate system. Later, the model validations were performed with the benchmark of a solid particle settlement in a stagnant fluid and particle motion in a shear flow, and the results show that the present model is capable of predicting the solid particle motion in the fluid flow. Finally, the model is adopted to investigate the dendritic growth and motion in a forced fluid flow (laminar flow or rotational flow), and the dendrite settlement in a terrestrial environment. The results show that when the forced fluid flow is a laminar flow, the free dendrite would be driven to translate, and the relative velocity between the dendrite and flow fluid decreases, resulting in weak influence of fluid flow on the dendritic growth. When the forced fluid flow is a rotational fluid flow, the dendrite would centrifugally rotate on the domain center with a counterclockwise self-spinning, and the rotation radius becomes larger and larger. For the case of dendrite settlement in a terrestrial environment, the relative movement between the dendrite and melt promotes the downward branch growth, but inhibits the upward branch growth, and two vortices form at the wake region of dendrite. Therefore, the settling dendrite shows a significant asymmetrical morphology.

On the unsteady rotating fluid flow in a uniformly rotating or fixed vertical cylinder

In this paper we consider the properties of the transient process that always precedes (or completes) the onset (cessation) of steady fluid flow in a uniformly rotating vertical cylinder. First, we give an elementary (without using the Navier–Stokes equations) and detailed derivation of the equation describing the space and time distribution of angular speeds in a rotating viscous fluid. This expression is used further for the numerical construction of the dynamic surface profiles. We find that in the case of an abrupt stop of cylinder rotation, these profiles have an inflection point, while for an abrupt start of cylinder rotation such a peculiarity is absent. We provide a simple physical explication of this fact. The issues outlined in this article will be useful for undergraduate students studying the basics of fluid mechanics.

Возникновение вращения жидкости при охлаждении свободной границы

For the Navier-Stokes system and the heat equation with vanishing viscosity, the stationary thermocapillary flow of an incompressible fluid in a horizontal layer of infinite thickness is calculated. The layer is bounded above by a free non-deformable boundary on which an uneven temperature distribution is specified. In the approximation of the boundary layer, asymptotic expansions of the solution of the problem are constructed. The main terms of the asymptotics satisfy the Prandtl equations of the boundary layer. Two types of regimes in the boundary layer are calculated - non-swirling and rotational fluid flows. Rotational regimes of fluid flows arise as a result of bifurcation of non-swirling regimes in the boundary layer. Bifurcation points are found by solving a boundary value problem for eigenvalues. It is shown that rotational regimes arise only when the free boundary is locally cooled. When the boundary is heated, fluid rotation does not occur. Two types of rotational modes are numerically calculated. All modes exist only if the velocity of the external fluid flow does not exceed the bifurcation value. The modes of the first type have axial symmetry. There are only two such modes. Other modes do not have axial symmetry. For modes of the second type, an exact solution in cylindrical coordinates is obtained. These modes depend on two independent parameters that fill the circle of unit radius. So, at the bifurcation point, many rotational regimes arise, which are a two-parameter family.

MHD Rotating Fluid Flow past a Vertical Plate that Applies Arbitrary Shear Stress with Ramped Wall Temperature

Heat transfer in rotating, incompressible viscous ?‡uid near an in?…nite ver-tical plate that applies a time-dependent shear stress f(t) with ramped wall temperatureis investigated. Closed form exact solutions of the dimensionless governing equations alongwith imposed initial and boundary conditions are determined using the Laplace transformtechnique. These solutions are uncommon in literature and can generate exact solutions forany motion of problem with technical relevance of this type. The e?¤ects of di?¤erent systemparameters, such as Ekman number, Grashof number, Prandtl number, magnetic numberand time on the velocity is examined in detail. Its in?‡uence on the ?‡uid motion is graphicallydisplayed. Some special cases together with particular cases are considered.

Bovine sperm selection procedure prior to cryopreservation for improvement of post-thawed semen quality and fertility

BackgroundThe application of cryopreservation and artificial insemination technology have contributed to the advancement of animal reproduction. However, a substantial proportion of spermatozoa undergoes alterations and loses their fertility during cryopreservation, rendering the frozen-thawed semen impractical for routine use. Cryopreservation is known to reduce sperm lifespan and fertility. Variation in cryosurvival of spermatozoa from different sires and even with the individual sire is common in artificial insemination (AI) centers. Our goal is to improve post-thawed semen quality by optimization of cryopreservation technique through sperm selection prior to cryopreservation process.ResultsOur strategy of sperm selection based on rheotaxis and thermotaxis (SSRT) on macrosale in a rotating fluid flow demonstrated the ability to maintain the original pre-freezing structural integrity, viability and biological function related to fertilization competence. This strategy has a positive effect on the cryosurvival and fertilizing abilities of spermatozoa as supported by the improvement on pregnancy rate of Japanese Black heifers and Holstein repeat breeders. This technique protected further sublethal damage to bovine spermatozoa (higher % cryosurvival than the control) and resulted in the improvement of DNA integrity. Prefreeze selected spermatozoa demonstrated slower and controlled capacitation than unprocessed control which is thought to be related to sperm longevity and consequently to appropriate timing during in vivo fertilization.ConclusionsThese results provide solid evidence that improvement of post-thawed semen quality by SSRT method is beneficial in terms of cryosurvival, longevity of post-thawed sperm, and optimization of in vivo fertilization, embryo development and calving as supported by the favorable results of field fertility study.

The Effect of Temperature and Twist Ratio from Twisted Tape Insert to Pumping Power in Concentric Exchange Tools using Nanofluida TiO2 and Oli Termo XT-32

The heat exchanger is a device used to heat between two or more fluids. Heat exchangers can use fluid flow or construction. Heat exchangers are widely used in engineering applications. The heat exchanger has long been recognized by industries that relate to heat transmission phenomena. Improve the speed of all types of heat exchangers widely in the industry, in the process of retrieval (heat recovery process), air conditioning, and chemical reactors. Increasing the amount of light flow can be done in several ways, namely: flowing inequality, damaging the boundary layer, changing the fluid flow, and rotating fluid flow (vortex flow). One of the techniques used to increase the heat coefficient of convection is to provide insert material or often called Insert. The research methodology was to determine the effect of the rotational ratio of the insertion bent band on the pumping power of the pipe heat exchanger by using TiO2 nanofluid with a heat transfer oil base fluid (thermo XT32). This research was carried out with experimental methods, as for the tools and research materials in this case: primary fluid of thermo XT32, TiO2 nanoparticles, and an annular channel concentric pipe heat exchanger by inserting a bent band. In and out data (Th, i and Th, o), the temperature of the fluid in and out of the annulus (Tc, i and Tc, o), the outer wall temperature of the inner tube (Tw1, Tw2, Tw3, Tw4), and the water height difference on the manometer. Data collection was carried out with TiO2 particle nano samples with a volume fraction of 0.3% Vol, without a bent band. Insert (plain tube) and rotate the tape with a touch ratio of 3, 6, and 9. The results of the research carried out on the conclusion of the rotational ratio in the band bending the insertion of the pumping power of the heat exchanger. This proved the pumping power increases with decreasing rotational ratio from a bent band, the addition of a twisted tape insert can increase the pumping power when compared to a pipe heat exchanger without concentrically turning the inserted tape (plain tube), this is proven by using a twisted tape insert with a twist ratio of 3. It requires a pumping power of 87.71 W / m2 to be able to drain TiO2 nanofluid, with a volume fraction of 0.3% Vol at a fluid temperature of 60 °C whereas when compared to a heat exchanger without turning the inserted tape (plain tube), it only requires pumping power of 17.73 W / m2. to be able to drain nanofluid in a heat exchanger.

A variational principle for fluid sloshing with vorticity, dynamically coupled to vessel motion.

A variational principle is derived for two-dimensional incompressible rotational fluid flow with a free surface in a moving vessel when both the vessel and fluid motion are to be determined. The fluid is represented by a stream function and the vessel motion is represented by a path in the planar Euclidean group. Novelties in the formulation include how the pressure boundary condition is treated, the introduction of a stream function into the Euler–Poincaré variations, the derivation of free surface variations and how the equations for the vessel path in the Euclidean group, coupled to the fluid motion, are generated automatically.

Buoyancy Effects on Unsteady MHD Chemically Reacting and Rotating Fluid Flow Past a Plate in a Porous Medium

An unsteady magnetohydrodynamic natural convection transfer of mass and heat flow over a vertical porous sheet under the influence of thermal radiation and thermo-diffusion effect. The dimensionless governing equations are solved analytically by employing Laplace transform technique. The impact of various physical parameters on momentum, energy and concentration are discussed and analyzed with the aid of graphs. Furthermore, the numerical values for local Skin friction, Nusselt number and Sherwood number are noted and examined. Increasing the values of thermal diffusion results in increasing of the concentration, but it decreases with Schmidt number. Skin friction reduces for increasing values of thermo-diffusion are discussed with the help of tables.

Field Synergy Principle For Natural Convective Rotating Fluid Flow Past a Vertical Cylinder

In the present research work, the effects of thermal and induced magnetic fields on the natural convective rotating fluid flow past the vertical cylinder are presented. The numerical solution of the unsteady field variables is obtained by solving the governing non-dimensional non-linear equations. The effects of the Prandtl, Taylor and Chandrasekhar numbers on the induced magnetic field, average momentum and heat transfer coefficients are presented graphically. The field synergy/ coordination principleis discussed to understand the enhancement of convective heat transfer. Increasing values of synergy co–insides with the increasing rate of heat transfer.

Finite element analysis on transient magnetohydrodynamic (MHD) free convective chemically reacting micropolar fluid flow past a vertical porous plate with Hall current and viscous dissipation

This article deals with boundary layer analysis of magnetohydrodynamics on an unsteady chemically reactive micropolar rotating fluid flow past a semi-infinite vertical plate with the impact of Hall current and viscous dissipation. The relevant equations on the fluid flow have been developed under Boussinesq approximation. The governing partial differential equations are transformed into a set of coupled partial differential equations using suitable dimensionless quantities. The resultant equations are solved numerically using variational finite element method. A parametric study illustrating the influence of different pertinent parameters is performed and the numerical results for translational velocity, microrotation velocity, temperature and concentration distributions near the boundary layers are discussed and presented graphically for the parametric variations. Finally, the skin-friction, wall couple stress, surface heat transfer and mass transfer rate dependency on the emerging thermo-physical parameters are also tabulated. The finite element code is benchmarked with the results reported in the literature to check the validity and accuracy under some limiting cases and excellent agreement with published solutions is achieved.

Rotating Fluid Flow on MHD Radiative Nanofluid past a Stretching Sheet

The present study is aimed at examining the unsteady MHD heat and mass flow of a nanofluid passing a stretching sheet with thermal radiation in a rotating system. The governing boundary layer equations as continuity, momentum, energy, concentration equation were solved by introducing a time dependent length scale in a similarity approach. Obtained nonlinear coupled equations along with the appropriate boundary conditions are then solved by Nactsheim-Swigert shooting iteration technique together with Runge-Kutta six order scheme. The effect of different dimensionless parameters on the flow field as magnetic parameter, rotational parameter, radiation parameter, Prandtl number, Eckert number, Lewis number, Brownian motion parameter, thermophoresis parameter was investigated. The distribution of the primary velocity, secondary velocity, temperature, concentration, local skin-friction coefficients, Nusselt number and the Sherwood number with the effect of the important parameters entering into the problem separately and reported graphically.

Linear instability in Rayleigh-stable Taylor-Couette flow.

Rayleigh's stability criterion describes the inviscid stability of rotating fluid flows. Despite the limitations of the criterion due to the assumptions used, it has been widely viewed as a general stability barrier in various rapidly rotating flows. However, contrary to previous belief, a linear instability is identified in Rayleigh-stable Taylor-Couette flow. The instability is found in cyclonic rapid rotation regime, for almost the entire range of the radius ratio of the cylinders.

Mhd heat absorbing and rotating fluid flow through a porous plate

Mhd heat absorbing and rotating fluid flow through a porous plate

Numerical analysis of the wake of a 10kW HAWT

With the rising of wind power industry and the ever-growing scale of wind farm, the research for the wake performance of wind turbine has an important guiding significance for the overall arrangement of wind turbines in the large wind farm. The wake simulation model of 10kW horizontal-axis wind turbine is presented on the basis of Averaged Navier-Stokes (RANS) equations and the RNG k-ε turbulence model for applying to the rotational fluid flow. The sliding mesh technique in ANSYS CFX software is used to solve the coupling equation of velocity and pressure. The characters of the average velocity in the wake zone under rated inlet wind speed and different rotor rotational speeds have been investigated. Based on the analysis results, it is proposed that the horizontal spacing between the wind turbines is less than two times radius of rotor, and its longitudinal spacing is less than five times of radius. And other results have also been obtained, which are of great importance for large wind farms.

Rotationally induced fingering patterns in a two-dimensional heterogeneous porous medium.

Rotating fluid flows under two-dimensional homogeneous porous media conditions (or in a rotating Hele-Shaw cell) reveal the development of complex interfacial fingering patterns. These pattern-forming structures are characterized by the occurrence of finger competition events, finger pinch-off episodes, as well as by the production of satellite droplets. In this work, we use intensive numerical simulations to investigate howthesefully nonlinear pattern growth phenomena are altered by the presence of permeability heterogeneities in the rotating porous medium. This is done by employing a diffuse-interface Darcy-Cahn-Hilliard description of the problem and considering a permeability field presenting a log-Gaussian distribution, characterized by a variance s and a correlation length l. We study how the heterogeneity measures s and l couple to the governing hydrodynamic dimensionless parameters of the problem and introduce important changes on the pattern formation dynamics of the system.