scholarly journals Maghetohydrodynamic flows of micro/nano fluids through thin capillaries

2019 ◽  
pp. 32-36
Author(s):  
L. V. Batyuk ◽  
N. M. Kizilova
Keyword(s):  
Magnetic Field ◽  
Production Condition ◽  
Circular Cross Section ◽  
Velocity Slip ◽  
Slip Boundary Condition ◽  
Minimum Entropy ◽  
Pressure Drops ◽  
Material Parameters ◽  
Slip Boundary ◽  
Mhd System

Steady magnetohydrodynamic (MHD) flows of suspensions of conducting micro/nanoparticles through a thin tube of a circular cross-section in a transverse constant magnetic field driven by a constant pressure drops at the ends of the tube is studied. The governing MHD system of equations for a viscous incompressible micro/nanofluid in the non-induction approximation is solved with the second order velocity slip boundary condition at the wall of the tube. The material parameters of the fluid are considered as nonlinear functions of the particle concentration according to the mixture models of suspensions and electric conductivity theory. The velocity field, pressure, electric current and magnetic field have been computed as series expansions. The influence of two non-dimensional slip coefficients of the flow rate and wall shear stress is studied. Optimal concentrations of the micro/nanoparticles in the suspensions have been computed from the minimum entropy production condition for different slip conditions, material parameters, magnetic fields and flow regimes (Reynolds and Hartmann numbers).

The effect of second order slip condition on MHD nanofluid flow around a semi-circular cylinder

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jiahui Cao ◽  
Jing Zhu ◽  
Xinhui Si ◽  
Botong Li
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Boundary Condition ◽  
Circular Cylinder ◽  
Volume Fraction ◽  
Velocity Slip ◽  
Slip Boundary Condition ◽  
Second Order ◽  
Ansys Fluent ◽  
Slip Boundary

Abstract Steady forced convection of non-Newtonian nanofluids around a confined semi-circular cylinder subjected to a uniform magnetic field is carried out using ANSYS FLUENT. The numerical solution is obtained using the finite volume method. The user-defined scalar (UDS) is used for the first time to calculate the second order velocity slip boundary condition in semi-circular curved surface and the calculated results are compared with those of the first order velocity slip boundary condition. Besides, the effects of volume fraction, size, type of nanoparticles and magnetic field strength on heat transfer are studied. The present study displays that adding nanoparticles in non-Newtonian fluids significantly enhances heat transfer. In addition, it is observed that the heat transfer rate decreases first and then increases with the increase of Hartmann number. The effects of blocking rate on Nusselt number, wake length and heat transfer effect are shown in the form of graphs or tables.

scholarly journals Effect of Velocity Slip Boundary Condition on the Flow and Heat Transfer of Cu-Water and TiO2-Water Nanofluids in the Presence of a Magnetic Field

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Abdelhalim Ebaid ◽  
Fahd Al Mutairi ◽  
S. M. Khaled
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Fluid Velocity ◽  
Velocity Slip ◽  
Slip Boundary Condition ◽  
Dual Solutions ◽  
Slip Condition ◽  
Shrinking Sheet ◽  
Physical Parameters ◽  
Flow And Heat Transfer

In nanofluid mechanics, it has been proven recently that the no slip condition at the boundary is no longer valid which is the reason that we consider the effect of such slip condition on the flow and heat transfer of two types of nanofluids. The present paper considers the effect of the velocity slip condition on the flow and heat transfer of the Cu-water and the TiO2-water nanofluids over stretching/shrinking sheets in the presence of a magnetic field. The exact expression for the fluid velocity is obtained in terms of the exponential function, while an effective analytical procedure is suggested and successfully applied to obtain the exact temperature in terms of the generalized incomplete gamma function. It is found in this paper that the Cu-water nanofluid is slower than the TiO2-water nanofluid for both cases of the stretching/shrinking sheets. However, the temperature of the Cu-water nanofluid is always higher than the temperature of the TiO2-water nanofluid. In the case of shrinking sheet the dual solutions have been obtained at particular values of the physical parameters. In addition, the effect of various physical parameters on such dual solutions is discussed through the graphs.

Analytical Solution of Slip Flow of Nanofluids over a Permeable Wedge in the Presence of Magnetic field

2011 ◽  
Vol 354-355 ◽  
pp. 45-48 ◽  
Author(s):  
Jia Jia Niu ◽  
Lian Cun Zheng ◽  
Xin Xin Zhang ◽  
Chun Rui Li
Keyword(s):  
Magnetic Field ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Slip Flow ◽  
Slip Boundary Condition ◽  
Skin Friction Coefficient ◽  
Nonlinear Ordinary Differential Equation ◽  
Local Similarity ◽  
Slip Boundary ◽  
Layer Analysis

In this paper, a boundary layer analysis is presented for the slip flow of three types of incompressible viscous nanofluids past a permeable wedge in the presence of a magnetic field. Due to the appearance of a slip boundary condition at the surface, local similarity solution of the reduced nonlinear ordinary differential equation is obtained by the HAM coupled with minimizing the square residual error. The effects of pertinent parameters, such as the magnetic parameter, the solid volume fraction of nanoparticles, the slip parameter and the type of nanofluid on the flow, are analyzed and studied in details. It is found that Ag-water has the highest skin friction coefficient at the surface compared with the others.

scholarly journals Slip boundary condition of heat flux in Knudsen layers

2014 ◽  
Vol 470 (2161) ◽  
pp. 20130578 ◽  
Author(s):  
Mingtian Xu
Keyword(s):  
Boundary Condition ◽  
Heat Flux ◽  
Velocity Slip ◽  
Slip Boundary Condition ◽  
Mean Free Path ◽  
Knudsen Layer ◽  
Boltzmann Transport ◽  
Slip Boundary ◽  
The Mean ◽  
Solid Walls

In a Knudsen layer with thickness comparable to the mean free path, collisions between heat carriers and solid walls play an important role in nanoscale heat transports. An interesting question is that whether these collisions also induce the slip of heat flow similar to the velocity slip condition of the rarefied gases on solid walls. In this work based on the discrete Boltzmann transport equation, the slip boundary condition of heat flux on solid walls in the Knudsen layer is established. This result is exemplified by the slip boundary condition of heat flux in nanowires, which has been proposed in a phenomenological way.

scholarly journals Slip Flow of Kerosene Oil Based SWCNT Nanofluid over Stretching Sheet with Radiation and Suction/Injection Effects

2021 ◽  
Vol 6 (3) ◽  
pp. 860-877
Author(s):  
Susheela Chaudhary ◽  
Kiran Kunwar Chouhan ◽  
Santosh Chaudhary
Keyword(s):  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Slip Flow ◽  
Velocity Slip ◽  
Slip Boundary Condition ◽  
Skin Friction Coefficient ◽  
Single Wall Carbon Nanotubes ◽  
Local Skin ◽  
Slip Boundary ◽  
Similarity Transformations

Present study numerically investigates a two dimensional steady laminar boundary layer nanofluid flow of single-wall carbon nanotubes (SWCNTs) immersed into kerosene oil, due to a linearly stretched sheet. Flow is subjected to the slip boundary condition and suction/injection effects. Employing suitable similarity transformations, governing PDEs of the arising problem are converted into coupled nonlinear non-dimensional ordinary differential equations. A set of obtained ODEs with assisting boundary conditions is solved numerically by applying finite element method (FEM). Effect of pertinent factors, velocity slip parameter, suction/injection parameter and solid volume fraction parameter on non-dimensional velocity and temperature profiles are characterized graphically. In addition, physical emerging parameters, local Nusselt’s number and local skin friction coefficient are computed and presented via table. Furthermore, derived numerical values of shear stress and heat flux at the surface are compared with previously published results.

scholarly journals Slow Extensional Flow Past a Non-Homogeneous Porous Spherical Shell

2013 ◽  
Vol 18 (2) ◽  
pp. 491-502 ◽  
Author(s):  
S.C. Rajvanshi ◽  
S. Wasu
Keyword(s):  
Spherical Shell ◽  
Finite Thickness ◽  
Extensional Flow ◽  
Radial Distance ◽  
Velocity Slip ◽  
Slip Boundary Condition ◽  
Analytical Investigation ◽  
Slip Boundary ◽  
Flow Past ◽  
Porous Spherical Shell

An analytical investigation of extensional flow past a porous spherical shell of finite thickness with velocity slip at the surface is presented. The permeability of the shell varies continuously as a function of the radial distance. The flow in the porous region is assumed to obey Darcy’s Law. The drag has been calculated in terms of normal volume flux rate per unit area of the outer and inner surfaces. Particular cases of flow past a homogeneous sphere and no-slip boundary condition have been deduced.

Simulation of Liquid Flowing over Surfaces with Micro-Structure

2011 ◽  
Vol 88-89 ◽  
pp. 628-631
Author(s):  
Zhi Jun Xi ◽  
Gang Li
Keyword(s):  
Pressure Drop ◽  
Flow Velocity ◽  
Slip Velocity ◽  
Velocity Slip ◽  
Slip Boundary Condition ◽  
Rectangular Microchannel ◽  
Slip Boundary ◽  
Free Air ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

The exist shear-free air-water interface at the fluid-solid houndary is one important reason for drag reduction of ultrahydrophobic surface. Rectangular microchannel flows with various periodic micro-structured wall by introducing velocity slip boundary condition at low Reynolds number is investigated through computational fluid dynamics simulations(CFD). The purpose of the current study is to numerically find out the effects of periodic micro-structured wall on the flow resistance in rectangular microchannel with the different spacings between microridges ranging from 15 to 60 μm. The simulative results indicate that pressure drop with different spacing between microridges increases linearly with flow velocity and decreases monotonically with slip velocity; pressure drop reduction also increases with the spacing between microridges at the same condition of slip velocity and flow velocity.

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