Permeable Cylinder Research Articles

Impacts of Cattaneo–Christov heat flux on the radiative MHD nanofluid flow past a stretched cylinder under multiple slip conditions

AbstractThis investigation explores the features of velocity distribution, mass and heat transmissions of nanoliquid stream over a permeable cylinder accompanied by Cattaneo–Christov heat model and thermal radiation with nonlinear sort. Multiple slip conditions have been also encountered here. A magnetic force is oriented along vertically upward. The existence of thermophoresis together with Brownian motion has been assumed here. The foremost equations and associated boundary conditions have been normalized through the similarity technique. Then we solve the system numerically along with the fourth‐order Runge–Kutta shooting scheme by using the software MAPLE‐17 and round it with our preassigned accuracy level. The obtained outcomes are epitomized by tables and graphs. All of the impacts have been compared in suction and injection correspondingly and explained with proper reasoning. In charts, the physical consignments (such as Sherwood number, Nusselt number and skin friction) reveal the transference of mass and temperature and amount of friction by nanoparticles in the nanocomposition. For suction, the nanofluidic temperature gradually diminished due to the advanced thermal relaxation, whereas the contrary fact is exhibited in injection. The relaxation parameter of concentration provides a positive influence on mass transmission. The rates of amplification of this transportation are 1.99% and 3.87%, measured in consideration of injection and suction, respectively. Thermal radiation influenced the fluid's temperature in a positive direction. It increases Nusselt number with 41.75% in suction, and 45.21% is recorded for injection.

Study of Different Heating Effects on Two-Phase Flow of Magnetized Couple Stresses Over a Permeable Stretching Cylinder with Velocity Slip and Radiation

Study of Different Heating Effects on Two-Phase Flow of Magnetized Couple Stresses Over a Permeable Stretching Cylinder with Velocity Slip and Radiation

Gyrotactic microorganisms and viscous dissipation features on radiative Casson nanoliquid over a moving cylinder with activation energy

Role of activation energy, nanoparticles and gyrotactic microorganisms with bioconvection has a great significance in geothermal engineering, biotechnology, oil reservoir, heat exchanger, chemical engineering, food processing, biosensors, water emulsion and cooling devices. This study communicates a numerical exploration regarding the activation energy and bioconvection ramifications in the development of thermal extrusion of chemically reactive Casson nanoliquid over a permeable cylinder under the repercussions of gyrotactic microorganism and viscous dissipation. Additionally, reverberations of activation energy and nonlinear radiations are enumerated. Revised novel nanofluid model is taken into consideration. Basic PDEs of chosen investigation are developed by deploying boundary layer theory and redeveloped into nonlinear coupled ODEs by employing relevant transformation. Numerical solutions are established through Fehlberg RK45. For the validation of present exploration, a comparison assessment is effectuated and vouchsafed in excellent agreement. The outcomes of this novel study reveal that microorganism density number is deprecated for higher approximation of Peclet number and microorganism difference parameter but opposite behavior can be perceived enriched Eckert number. Further, wall heat flux is disparaged due to exaltion of bioconvection Rayleigh number.

Effect of transverse magnetic field on wake dynamics and heat transfer through a porous circular cylinder

AbstractA two‐dimensional numerical simulation using the commercial computational fluid dynamics package ANSYS Fluent 15.0 is performed to investigate the effect of a transverse magnetic field on the wake dynamics around a heated porous circular cylinder. The study is conducted considering a Newtonian, incompressible, and electrically conductive fluid with constant properties for the low Reynolds number laminar regime. In the range of Reynolds number (Re = 10–40), recirculating vortices are observed to penetrate (or detach) into (from) the porous cylinder surface depending on the Darcy number, Da (10−6 to 10−2). The effect of the magnetic field parameter (Hartmann number) Ha (0–10) on the detachment and penetration characteristics of a porous cylinder is reported for the first time. A steady separated flow behind the cylinder turns into an attached flow at a critical magnetic field strength. Accordingly, the critical Hartmann number (Hacr) is estimated for the complete suppression of the flow separation behind the porous cylinder. Hacr is found to decrease with an increase in Da and a decrease in Re. The wake behind the cylinder is also found to be detached from the cylinder surface at a particular value of the magnetic field strength termed as the detachment Hartmann number (Had). Had also decreased with an increase in Da and decrease of Re. In addition, the effect of Ha on the separation angle, recirculation length, detachment length, and drag coefficient is also discussed. Furthermore, the effect of the magnetic field on the forced convective heat transfer characteristics is also studied considering various fluids (Prandtl number, Pr = 0.02, 0.71, and 7) past the circular permeable cylinder. At a particular Pr, the heat transfer rate is almost invariant for low permeability, whereas it increases significantly at higher permeability with an applied magnetic field. The rate of heat transfer increases with the Prandtl number for all Hartmann and Darcy numbers. Finally, a correlation is developed to predict the average heat transfer as a function of Re, Pr, Da, and Ha.

Semi-analytical study of the first order horizontal force induced by oblique waves on the array of circular columns of offshore wind turbines equipped with permeable cylinders

This paper studied the incident of linear oblique waves to circular columns of offshore wind turbines in conjunction with concentric and non-concentric thin permeable cylinders. The unique research objective of this work is to assess the possibility of using permeable vertical cylinders to reduce wave forces on the column of offshore wind turbines. The developed semi-analytical method benefits from the mathematical relation between Bessel functions to express the BEM-related integrals in the Fourier modes of the Hankel function and to calculate singular integrals indirectly. Moreover, Graf's addition theorem for Bessel functions was used for shifting between different coordinate systems to avoid calculating related integrals numerically. The basic geometries parameters such as permeability parameter, cylinders arrangement and the radius of the permeable cylinders, and the wavenumber on the horizontal wave-induced force were studied. The results are presented in graphs. The results indicate that covering the columns of DeepCwind and OC3 wind turbines with the permeable cylinders or using the permeable cylinders upstream helps reduce the horizontal wave-induced force at a particular permeability parameter. The results of this research are beneficial in the design of columns of offshore wind turbines and other structures with vertical piles, such as semi-submersibles.

Magnetohydrodynamic Flow and Heat Transfer Analysis on Ethylene Glycol Based Nano Fluid Over a Vertical Permeable Circular Cylinder with Joule Heating and Radiation

This research’s contribution is towards determining heat transfer characteristics of Ag–C2H6O2 and Cu–C2H6O2 nano fluid over a vertical porous circular cylindrical surface. The mixed convection flow in the presence of electric conductivity, Joule heating and thermal radiation near a stagnation point is considered for investigation. Ethylene glycol is taken as base fluid while copper and silver are nanoparticles. Through similarity transformations, the governing PDEs for momentum, energy, and concentration are turned into ODEs, which are then interpreted using a fourth-order exactness programme (Bvp4c). The parametric impacts on concentration, temperature and velocity are thoroughly discussed graphically while impact on the rate of heat transfer, skin friction and rate of mass transfer is obtained in numeral form. The obtained results are compared to published literature and a comparison between Ag–C2H6O2 and Cu–C2H6O2 nano fluids is demonstrated.

The effect of boundary conditions on the stability of two-dimensional flows in an annulus with permeable boundary

Our aim is to study the effect of the outflow boundary conditions on the stability of incompressible flows in a domain with a permeable boundary. For this purpose, we examine the stability of the Couette flow with the radial throughflow between permeable cylinders. Most earlier studies of this flow employed the boundary conditions that prescribe all components of the flow velocity on both cylinders. Taking these boundary conditions as a reference point, we investigate the effect of imposing different outflow boundary conditions. These conditions prescribe the normal stress and either the tangential velocity or the tangential stress. It turns out that both sets of boundary conditions make the corresponding steady flows more unstable. In particular, it is shown that even the classical (purely azimuthal) Couette flow becomes unstable to two-dimensional perturbations if one of the cylinders is permeable and the normal stress (rather than normal velocity) is prescribed on that cylinder.

Assorted Graphene-Based Nanofluid Flows Near a Reversed Stagnation Point over an Inclined Permeable Cylinder

Assorted Graphene-Based Nanofluid Flows Near a Reversed Stagnation Point over an Inclined Permeable Cylinder

Axisymmetric forced flow of nonhomogeneous nanofluid over heated permeable cylinders

Investigation of nanofluid properties around a cylinder is carried out for laminar steady-state axisymmetric flow. This study focuses on the porous medium with the existence of laminar and incompressible Newtonian nanofluid in two dimensions and develops an alternative model to avoid the single-phase model limitations considering the influence of Brownian motion and thermophoresis parameter for the nonhomogeneous nanofluid on permeable cylinders. Employing group method and similarity transformation, the governing mathematical model was transformed into a simpler system of ordinary differential equations. The system of equations is numerically computed. The numerical investigation included different governing parameters namely: Prandtl number , thermophoresis parameter , Brownian motion parameter , Reynolds number , and Schmidt number, Sc. Studying these parameters helps to obtain the characteristic of the flow and heat transfer. The numerical examination is illustrated in graphs to examine their effect on different fluid characteristics. Increasing Pr hurdles the nanofluid velocity, temperature, and nanoparticles concentration, while it increases the pressure due to the viscosity increment. Moreover, increasing Nt activates the thermal energy of the nanofluid which in turn increases velocity, temperature distribution, and nanoparticles concentration. A comparison between the obtained results and the previously published results indicated an excellent agreement.

MHD Flow around Circular Cylinder UnderControl through three Different magnetic Permeability Status

Through the current work, the flow around an insulating cylinder of various magnetic permeability, submitted to a flow of an incompressible electrically conducting fluid has been investigated. The homogeneous fluid flow and the homogeneous applied magnetic field are aligned at infinity. When the cylinder has the similar magnetic permeability as the fluid, the applied field is not influenced by the cylinder. However, when the cylinder has a different magnetic permeability than that of the fluid, the applied field is agitated by the cylinder and then the flow structures will become different from those of the previous case. Consequently, two cases can be distinguished following the last state whereas the cylinder magnetic permeability may have less or greater value than the fluid one’s. The best agreed results that have been obtained following the comparison to the literature magnetic field behaviors were selected .The event has been occurred, where the convergence and divergence of the magnetic stream lines were realized to the previous both cases of magnetic permeability situations, respectively. In fact, an important influence of magnetic field on the fluid has been occurred. Consequently, it can be concluded that the fluid has significant influences on the cylinder structure, through the impact of the fluid structure phenomenon, the shedding vortex process and its suppression. Accordingly, good results of drag aerodynamic coefficient evolution were obtained at the fixed value of the Reynolds number Re=550, for different Stuart numbers, greater than and lessen than a critical value adopting at N=0.8.

Numerical analysis of hydromagnetic transport of Casson nanofluid over permeable linearly stretched cylinder with Arrhenius activation energy

The current study is modelled to evaluate numerous flow applications in applied sciences espeically in nuclear reacting cooling, geothermal reservoirs, chemical engineering and thermal oil recovery. The present research investigates the magnetohydrodynamic transport of non-Newtonian Casson Nano fluid past due to stretching permeable cylinder by employing Buongiorno's mathematical model. Unlike the frequently used constant temperature and concentration boundary conditions, the present study employed convective boundary conditions. The influences of important sundary parameters like an inclination of magnetic field, joule heating, viscous dissipation, thermophoresis, Brownian motion, Arrhenius activation energy, and chemical reaction are taken into account. The physical flow phenomenon is modelled and after that transformed into a non-dimensional form by incorporating suitable similarity transforms. For solution purpose, Runge-Kutta-Fehlberg fourth-fifth order (RKF45) numerical integrating procedure along with shooting algorithm is adopted. Impacts of several emerging parameters on the velocity distribution, temperature distribution, and concentration distribution, coefficient of skin friction, Sherwood number, and Nusselt number are clarified via graphical and tabular results. It seems to establish that with the rise of chemical reaction parameter chemical reaction parameter the nanoparticles concentration distributions decline while the contrasting trend is perceived for activation energy parameter.

Analytical solution based on BEM to oblique waves scattering by thin arc-shaped permeable barrier applied for array of aquaculture cages

In this paper, linear oblique wave incident to a thin arc-shaped permeable barrier and an array of permeable circular cylinders was studied analytically. Two unique research objectives of this work include, considering the thickness for permeable material and the wavefield inside surrounded region by the permeable structure. The conventional boundary element method (BEM) is used to solve the governing equations of the problem. The mathematical relation between Bessel functions leads to representing the BEM-related integrals in the Fourier modes of Hankel function. This approach is useful as the singular integrals are accounted indirectly. Two basic geometries made by the permeable material are studied, including an arc-shaped and a circular geometry. The first geometry can represent a wave-breaking barrier in shallow water, while the latter can represent a floating fish farm in deep water. For the floating fish farm, the study is extended to the interaction between an array of cages. To quantify the amount of wave energy passed through the object, the Energy Transmission Index or ETI concept is introduced. ETI can be used as an indicator for permeable barriers performance.The results indicate that ETI is mostly a function of permeability rather than the wavenumber. In addition, the imaginary part of the permeability parameter plays an essential role in the problem of wave incident to permeable barrier, and it is necessary to be determined with enough accuracy. Furthermore, the shear force and bending moment on the base of the barrier and drift force and heeling moment on circular cylinders are studied. The results show, the drift force decreases as permeability and wavenumber increase. The results of this research are useful in the design of rigid circular offshore aquaculture fish cages and coastal barriers.

Comsolic solution of an elliptic cylindrical compressible fluid flow

In this article, the primary focus is to investigate the heat transfer effects with viscous compressible laminar flow in the permeable elliptic cylinder. The Reynolds number is kept 100 for flow to be laminar. The physics of heat transfer is selected to be coupled with the laminar flow. The results for particular step-size time for Velocity distribution, pressure profile, temperature profile, isothermal temperature contours, and drag coefficient have been analyzed. Mesh has been generated through COMSOL, mesh entities have been elaborated statistically. The maximum and minimum velocity profile is observed at the elliptical cylinder’s walls and upper, lower boundary respectively. The maximum velocity observed is 2.22 m/s. Pressure profile around elliptic corners is found maximum, distinct patterns are observed even under the influence of applied heat. Temperature is observed maximum at walls but it gradually increases as moving from the upper boundary towards the lower boundary. The isothermal contour patterns are observed maximum near the walls, drag coefficient of gradual decrease is observed. COMSOL multi-physics is utilized for mathematical modeling of problems and the Backward-Differentiation-Formula has been exploited to handle problems numerically. The results will help greatly to understand the characterizations of viscous fluids and in industries like air furnaces and automobile cooling systems.

Dual solution for double-diffusive mixed convection opposing flow through a vertical cylinder saturated in a Darcy porous media containing gyrotactic microorganisms

The steady mixed convection flow towards an isothermal permeable vertical cylinder nested in a fluid-saturated porous medium is studied. The Darcy model is applied to observe bioconvection through porous media. The suspension of gyrotactic microorganisms is considered for various applications in bioconvection. Appropriate similarity variables are opted to attain the dimensionless form of governing equations. The resulting momentum, energy, concentration, and motile microorganism density equations are then solved numerically. The resulting dual solutions are graphically visualized and physically analyzed. The results indicate that depending on the systems' parameters, dual solutions exist in opposing flow beyond a critical point where both solutions are connected. Our results were also compared with existing literature.

Linear Stability of a Steady Convective Flow between Permeable Cylinders

Linear stability analysis of a steady convective flow in a tall vertical annulus caused by nonlinear heat sources is conducted in the paper. Heat sources are generated as a result of a chemical reaction. The effect of radial cross-flow through permeable porous walls of the annulus is analyzed. The problem is relevant to biomass thermal conversion. The base flow solution is obtained by solving nonlinear boundary value problem. Linear stability analysis is performed, using collocation method. The calculations show that radial inward or outward flow has a stabilizing effect on the flow, while the increase in the Frank–Kamenetskii parameter (proportional to the intensity of the chemical reaction) destabilizes the flow. The increase in the Reynolds number based on the radial velocity leads to the appearance of the second minimum on the marginal stability curves. The rate of increase in the critical Grashof number with respect to the Reynolds number is different for inward and outward radial flows.

Longitudinal and transverse PAFs for an absorptive magneto-dielectric circular cylinder in light-sheets of arbitrary wavefronts and polarization.

Based upon the expression of the heat source function in photophoresis, generalized mathematical expressions for the longitudinal (L) and transverse (T) photophoretic asymmetry factors (PAFs) for a light-absorptive magneto-dielectric circular cylinder of arbitrary relative permittivity and permeability, illuminated by an arbitrarily shaped polarized light-sheet, are derived and computed. The L- and T-PAFs are directly proportional to the L and T components of the photophoretic force vector, respectively, induced by light absorption inside the particle, and their sign predicts the behavior of the force (pulling/attractive or pushing/repulsive). The partial-wave series expansion method in cylindrical coordinates is used, and the obtained mathematical expressions for the L- and T-PAFs depend on the beam-shape coefficients and the internal coefficients of the cylinder. Numerical examples illustrate the theory for TE and TM polarized plane waves, and nonparaxial Airy light-sheets with particular emphasis on absorption inside the cylinder and varying the Airy light-sheet parameters. The generalized expressions presented here are applicable to any light-sheet of an arbitrary wavefront, and offer additional quantitative observables for the analysis of the photophoretic force in applications in electromagnetic scattering, optical light-sheet tweezers, particle manipulation, radiative transfer, and other research fields.

Flow and heat transfer of nanofluid over a permeable cylinder with nonlinear thermal radiation

In current study, heat transfer and viscous dissipation effects in nanoliquid flow through a porous stretchable cylinder are examined. The upgraded heat transport rate in the base fluid with tiny-sized nanoparticles is investigated. Convective heating and non-linearly thermal radiation effects are investigated. In this analysis, solid particles M o S 2 & A g and base fluid engine-oil are used. Moreover, boundary layer approximations are used to model a set of PDEs. The structure model of PDEs is reduced into non-dimensional set of ODEs with the help of recommended similarity transformations. The converted equations jointly with specific boundary restrictions are solved numerically by using the bvp4c solver (shooting scheme) in computational software MATLAB. The behavior of prominent parameters against flow and thermal fields are analyzed. From the results, we observed that velocity enhances for larger solid volume fraction. Furthermore, temperature of fluid is increased via greater estimations of thermal Biot number. The nanofluid has improved heat transport rate and therefore the current analysis has many applications in nano-sized devices of cylindrical shapes.

Non-linear radiative bioconvection flow of cross nano-material with gyrotatic microorganisms and activation energy

Bioconvection with gyrotactic microorganisms has a significant role in biotechnology and biosensors. This paper communicates a theoretical numerical investigation regarding the transient bioconvection flow of chemically reactive cross nanofluid over a permeable cylinder under the impact of nonlinear radiation and binary chemical reactions. Additionally, Arrhenius activation energy influences are taken into account. Further, revise model of nanoparticles is considered in present investigation. Boundary layer theory is invoked to develop the basic PDEs of microorganisms field, nanoparticles concentration, energy, momentum and mass for bioconvection flow of cross nanofluid in cylindrical coordinate system and then altered into nonlinear ODEs by utilizing the transforming variables. Numerical solutions of obtained highly nonlinear ODEs system are achieved through shooting Fehlberg approach for both the cases of stretching cylinder aw well as shrinking cylinder. Numerical computations for surface drag force, mass transfer rate, density number of microorganisms and heat transfer rate are executed. It is interesting to found that the density number of microorganisms is depreciated for higher estimation of Peclet number, microorganisms difference parameter and bioconvection Rayleigh number in both cases of stretching cylinder as well as shrinking cylinder. Furthermore, nanoparticles concentration is accelerated for the augmented values of activation energy parameter in shrinking as well as stretching cylinder. For the authenticity of considered study, we have also made a comparative analysis with existing study and noticed to be in excellent agreement.

Stability Analysis of Unsteady Hybrid Nanofluid Flow Past a Permeable Stretching/Shrinking Cylinder

The study of boundary layer flow has gained considerable interest owing to its extensive engineering applications. Thus, this numerical study aims to investigate the stability analysis of unsteady flow in the hybrid Al2O3-Cu/H2O nanofluid past a shrinking permeable cylinder. The impacts of suction and unsteadiness parameters are considered in this study. The partial differential equations are converted into a system of nonlinear ordinary differential equations by selecting suitable similarity transformation and solved using the bvp4c code in the MATLAB program. The findings revealed that the existence of dual solutions is visible. The skin friction coefficient and the local Nusselt numbers of Al2O3-Cu/H2O increase with the inclusion of the suction parameter. The presence of the unsteadiness parameter actively promotes heat transfer degradation on the shrinking cylinder. Stability analysis indicates that a stable and physically realizable solution appeared in the first solution, whereas the second solution is unstable.

Analytical Solution for Wave Diffraction by a Concentric Three-Cylinder System near a Vertical Wall

In this study, a semi-analytical model was developed to study wave diffraction around a concentric three-cylinder system near a wall based on linear potential theory. As a critical element, the target problem is transformed into bidirectional incident wave diffraction around two concentric structures based on the image principle and an analytical solution is obtained through eigenfunction expansion combined with a matching technique and Graf’s addition theorem. The validity of the proposed model was verified by comparing its results to known values. Parametric studies on porosity, annular spacing, incident angle, space between the structure and wall, and water depth were performed. The hydrodynamic loads and free-surface elevations in the system were calculated and compared to those reported in existing works on impermeable and permeable cylinders near a wall. The results indicate that the wave loads and run-ups on the exterior cylinder increase significantly based on the existence of the wall. However, based on the presence of an exterior porous protective structure, a significantly reduced influence of the wall on the interior cylinder can be observed. Considering the widespread use of concentric circular structures in ocean engineering, it is essential to conduct study on the hydrodynamic performance of concentric systems near walls, which can provide useful information for the design of marine structures.