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P.A. Bakalis

Bio: P.A. Bakalis is an academic researcher from University of Patras. The author has contributed to research in topics: Laminar flow & Magnetic field. The author has an hindex of 4, co-authored 7 publications receiving 30 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, a numerical analysis was performed to study the fully developed laminar flow of an electrically conducting liquid metal between two concentric cylinders in the presence of an external transverse magnetic field.
Abstract: A numerical analysis is performed to study the fully developed laminar flow of an electrically conducting liquid metal between two concentric cylinders in the presence of an external transverse magnetic field. The outer cylinder is constant, and the inner cylinder is constant or is rotating at a constant angular velocity about its axis. The cylinders are maintained at uniform temperatures. The temperature difference between the walls creates buoyancy force, due to the density variations. The CVP numerical variational method is used for the study. The obtained results are compared for various angular velocities, Reynolds, Grashof, Prandtl, and Hartmann numbers.

11 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of the magnetic field on the ferrofluid flow was analyzed in the toroidal-poloidal coordinate system and the results confirmed the ability of the method to produce accurate results in curvilinear coordinates and stretched grids.
Abstract: The laminar fully developed ferrofluid flow of an otherwise magnetic fluid into a curved annular duct of circular cross section, subjected to a transverse external magnetic field, is studied in the present work. The specific geometry is chosen as it is encountered in heat exchangers and mixers where compactness is a priority. Results are obtained for different values of curvature, field strength, and particles’ volumetric concentration. A computational algorithm is used which couples the continuity, Navier Stokes, and magnetization equations using a nonuniform grid. The velocity–pressure coupling is achieved using the so-called continuity-vorticity-pressure variational equation method, adapted to the toroidal-poloidal coordinate system. The results confirm the ability of the method to produce accurate results in curvilinear coordinates and stretched grids, which is important for the standardization of the method’s application to generalized coordinate systems. Concerning the micropolar flow characteristics, the results reveal the effect of the magnetic field on the ferrofluid flow. It is shown that the axial velocity distribution is highly affected by the field strength and the volumetric concentration, that the axial pressure drop depends almost linearly on the field strength, and that a secondary flow is generated due to the combined effect of the external magnetic field and the curvature. The present analysis provides important insight into the effect of the three main parameters, revealing cases where a straight annular pipe might be preferable to a curved one and specific parts of the pipe that could be susceptible to enhanced loads, giving information that is crucial for design optimization.The laminar fully developed ferrofluid flow of an otherwise magnetic fluid into a curved annular duct of circular cross section, subjected to a transverse external magnetic field, is studied in the present work. The specific geometry is chosen as it is encountered in heat exchangers and mixers where compactness is a priority. Results are obtained for different values of curvature, field strength, and particles’ volumetric concentration. A computational algorithm is used which couples the continuity, Navier Stokes, and magnetization equations using a nonuniform grid. The velocity–pressure coupling is achieved using the so-called continuity-vorticity-pressure variational equation method, adapted to the toroidal-poloidal coordinate system. The results confirm the ability of the method to produce accurate results in curvilinear coordinates and stretched grids, which is important for the standardization of the method’s application to generalized coordinate systems. Concerning the micropolar flow characteristic...

9 citations

Journal ArticleDOI
TL;DR: In this paper, the steady laminar quasi-3D fully developed magnetohydrodynamic (MHD) flow of a liquid metal in a curved annular channel is studied in order to determine the effect of the magnetic field on the velocity distribution.
Abstract: Purpose – The steady laminar quasi-3D fully developed magnetohydrodynamic (MHD) flow of a liquid metal in a curved annular channel is studied in order to determine the effect of the magnetic field on the velocity distribution. The paper aims to discuss this issue. Design/methodology/approach – Due to the fluid motion under the effect of the applied transverse external magnetic field, an additional magnetic field and an electric current density are induced. A hybrid formulation is used for the induced electric current density, implementing for its axial component the Ohm’s law and for its transverse components the Ampere’s law. The suggested formulation (denominated h-formulation) is combined with the extended Continuity Vorticity Pressure numerical variational method for MHD flows. Findings – Results are obtained for different values of curvature ratios and Hartmann numbers. It is proved that as the strength of the magnetic field increases, two side regions of velocity jets are formulated in the right and...

8 citations

Journal ArticleDOI
TL;DR: In this paper, the authors studied the fully developed laminar magnetohydrodynamic and thermal flow of an electrically conducting liquid metal between two horizontal concentric cylinders, maintained at uniform temperatures, under the effect of an external transverse magnetic field.
Abstract: The purpose of this paper is to study the fully developed laminar magnetohydrodynamic (MHD) and thermal flow of an electrically conducting liquid metal between two horizontal concentric cylinders, maintained at uniform temperatures, under the effect of an external transverse magnetic field. The temperature difference between the walls creates buoyancy force, due to density variations. Three different models are compared for the solution of the electromagnetic variables. The φ-formulation, based on the electric potential equation, the b-formulation, based on the induced magnetic field and the hybrid h-formulation. A numerical method, based on the continuity vorticity pressure (CVP) variational method, is used for the coupling of the magnetohydrodynamic equations.

6 citations

Journal ArticleDOI
TL;DR: In this article, a laminar fully developed magnetohydrodynamic flow of a liquid metal into a curved pipe of circular cross section, subjected to a transverse external magnetic field, is studied.

5 citations


Cited by
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TL;DR: In this paper, a dual reciprocity boundary element (DRBEM) was extended to study the generalized magneto-thermo-viscoelastic problem in a rotating solid of functionally graded material (FGM) in the context of the Green and Naghdi theory of type III.
Abstract: A numerical model based on the dual reciprocity boundary element method (DRBEM) is extended to study the generalized magneto-thermo-viscoelastic problem in a rotating solid of functionally graded material (FGM) in the context of the Green and Naghdi theory of type III. The material properties of the solid have a gradient in the thickness direction and are anisotropic in the plane of the solid. An implicit-implicit staggered strategy was developed and implemented for use with the DRBEM to obtain a solution for the displacement and temperature fields. The accuracy of the proposed method was examined and confirmed by comparing the obtained results with those known previously. In the case of three-dimensional, a numerical scheme for the implementation of the method is presented and the numerical computations are presented graphically to show the effect of the energy dissipation on the temperature and displacement components.

44 citations

Journal ArticleDOI
TL;DR: A comprehensive survey of the literature in the area of numerical heat transfer (NHT) published in 2010 and 2011 has been conducted as mentioned in this paper, which can be used as a starting point for future work.
Abstract: Here a comprehensive survey of the literature in the area of numerical heat transfer (NHT) published in 2010 and 2011 has been conducted. Due to the immenseness of the literature volume, journals s...

30 citations

Journal ArticleDOI
TL;DR: In this paper, a mathematical model is presented to analyze the peristaltic flow of magnetized viscoelastic fluids through a deformable curved channel, where mass and momentum conservation equations are formulated in an intrinsic coordinate system and transformed with appropriate variables into a nondimensional system between the wave and the laboratory frames.
Abstract: A mathematical model is presented to analyze the unsteady peristaltic flow of magnetized viscoelastic fluids through a deformable curved channel. The study simulates the bio-inspired pumping of electroconductive rheological polymers which possess both electroconductive and viscoelastic properties. The Jeffrey viscoelastic model is utilized which features both relaxation and retardation terms of relevance to real polymers. A magnetic body force is incorporated for the influence of static radial magnetic field. The mass and momentum conservation equations are formulated in an intrinsic coordinate system and transformed with appropriate variables into a nondimensional system between the wave and the laboratory frames, under lubrication (i.e., low Reynolds number and long wavelength) approximations. Kinematic and no-slip boundary conditions are imposed at the channel walls. A magnetic body force is incorporated for the influence of static radial magnetic field in the primary momentum equation. An analytic approach is employed to determine closed-form solutions for stream function, axial pressure gradient, and volumetric flow rate. Spatiotemporal plots for pressure distribution along the channel (passage) length are presented to study the influences of curvature parameter, relaxation-to-retardation time ratio (Jeffrey first viscoelastic parameter) and Hartmann number (magnetic field parameter). The effects of these parameters on radial velocity distributions are also visualized. Cases of trapping and reflux in a curved channel are discussed. Streamline distributions are included to study trapping phenomena and to investigate more closely the impact of curvature, magnetic field, and viscoelastic properties on bolus evolution. The reflux or retrograde motion of the particles is studied by particle advection based on Lagrangian viewpoint. The simulations provide new insight into the mechanisms of pumping of electroconductive non-Newtonian liquids in realistic geometries.

30 citations

Journal ArticleDOI
TL;DR: In this paper, a numerical study of swirling flows with heat transfer generated by two rotating end disks inside a cylindrical enclosure having an aspect ratio equal to 2, filled with a liquid metal, and submitted to a vertical temperature gradient and an axial magnetic field is studied.
Abstract: In this article, a numerical study of swirling flows with heat transfer generated by two rotating end disks (co- and counter-rotating) inside a cylindrical enclosure having an aspect ratio equal to 2, filled with a liquid metal, and submitted to a vertical temperature gradient and an axial magnetic field is studied. The governing Navier-Stokes, energy, and potential equations along with appropriate boundary conditions are solved by using the finite-volume method. The flow and temperature fields are presented by stream function and isotherms, respectively. This flow is very unstable and reveals a great richness of structures. In an oscillatory regime, results are presented for various values of the Hartmann number, Ha = 5, 10, 20 and 30, and Richardson numbers, Ri = 0, 0.5, 1, 2 and 4, in order to see their effects on the value of the critical Reynolds number, Recr. Stability diagrams are established according to the numerical results of this investigation. These diagrams show the dependence of Recr with t...

18 citations

Journal ArticleDOI
TL;DR: In this article , a comprehensive review on fundamental understanding of field-induced thermal and rheological properties in magnetic fluids is provided, with the necessary background, key concepts, definitions, mechanisms, theoretical models, and experimental protocols.

17 citations