The magneto-hydrodynamic boundary layer in the two-dimensional steady flow past a semi-infinite flat plate, lII . The influence of an adverse magneto-dynamic pressure gradient

1963 ◽  
Vol 273 (1355) ◽  
pp. 518-537 ◽  
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Flat Plate ◽  
Dynamic Pressure ◽  
Two Dimensional ◽  
Conducting Liquid ◽  
Electrically Conducting ◽  
Hydrodynamic Boundary Layer ◽  
Layer Flow ◽  
The Magnetic Field

An investigation is made of the boundary-layer flow of a viscous electrically conducting liquid in the neighbourhood of a semi-infinite flat plate, the flow being opposed by a magneto-dynamic pressure gradient. The plate is assumed to be unmagnetized and the magnetic field well away from the plate is parallel to the plate.

Magnetohydrodynamic compressible laminar boundary-layer adiabatic flow with adverse pressure gradient and continuous or localized mass transfer

2001 ◽  
Vol 79 (10) ◽  
pp. 1247-1263 ◽  
Author(s):  
M Xenos ◽  
N Kafoussias ◽  
G Karahalios
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Pressure Gradient ◽  
Magnetic Parameter ◽  
Adverse Pressure Gradient ◽  
Adiabatic Flow ◽  
Electrically Conducting ◽  
Free Stream Mach Number ◽  
Layer Flow ◽  
The Magnetic Field

The problem of magnetohydrodynamic compressible boundary-layer flow over a flat plate, in the presence of an adverse pressure gradient, is studied numerically. The fluid is assumed to be Newtonian, electrically conducting and the magnetic field is constant and applied transversely to the direction of the flow. The fluid flow is subjected to a constant velocity of suction and (or) injection, continuous or localized, and there is no heat transfer between the plate and the fluid (adiabatic flow). The system of partial differential equations, describing the problem under consideration, is solved numerically by applying a modification of the Keller box technique. Numerical calculations are carried out for different values of the free-stream Mach number and the magnetic parameter for continuous or localized suction and (or) injection imposed at the wall. The results obtained are shown in the figures and their analysis shows that the flow field can be controlled by the application of a magnetic field as well as by continuous or localized suction and (or) injection. PACS Nos.: 51.00, 52.00

scholarly journals Numerical Analysis of Heat Transfer of Eyring Powell Fluid Using Double Stratification of Magneto-Hydrodynamic Boundary Layer Flow

2020 ◽  
pp. 91-108
Author(s):  
Wekesa Waswa Simon ◽  
Winifred Nduku Mutuku
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Boundary Layer ◽  
Nusselt Number ◽  
Thermal Stratification ◽  
Fluid Velocity ◽  
Double Stratification ◽  
Hydrodynamic Boundary Layer ◽  
Layer Flow ◽  
The Magnetic Field

Heat transfer fluids play a vital role in many engineering and industrial sectors such as power generation, chemical production, air-conditioning, transportation and microelectronics. Aim: To numerically investigate the effect of double stratification on magneto-hydrodynamic boundary layer flow and heat transfer of an Eyring-Powell fluid. Study Design: Eyring-Powell fluid is one of the non-Newtonian fluid that possess different characteristics thus different mathematical models have been formulated to describe such fluids by appropriate substitution into Navier-Stoke’s equations. The challenging complexity and the nature of the resultant equations are of great interest hence attract many investigations. Place and Duration of Study: Department of Mathematics and Actuarial Science, Kenyatta University, Nairobi, Kenya between December 2019 and October 2020. Methodology: The resultant nonlinear equations are transformed to linear differential equations by introducing appropriate similarity transformations. The resulting equations are solved numerically by simulating the predictor-corrector (P-C) method in matlab ode113. The results are graphically depicted and analysed to illustrate the effects of magnetic field, thermophoresis, thermal stratification, solutal stratification, material fluid parameters and Grashoff number on the fluid velocity, temperature, concentration, local Sherwood number and local Nusselt number. Results: The results show that increasing the magnetic field strength, thermophoresis, thermal stratification and solutal stratification lead to a decrease in the fluid velocity, temperature, Sherwood number, Nusselt number and skin friction while an increase in the magnetic field strength, thermal stratification, solutal stratification, and thermophoresis increases the fluid concentration. Conclusion: The parameters in this study can be varied to enhance heat ejection of Eyring-Powell fluid and applied in industries as a coolant or heat transfer fluid.

A problem of a viscoelastic magnetohydrodynamic fluctuating-boundary-layer flow past an infinite porous plate

1993 ◽  
Vol 71 (3-4) ◽  
pp. 97-105 ◽  
Author(s):  
Hany H. Sherief ◽  
Magdy A. Ezzat
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Uniform Magnetic Field ◽  
Free Stream ◽  
Porous Plate ◽  
Two Dimensional ◽  
Viscoelastic Parameter ◽  
Electrically Conducting ◽  
Porous Flat Plate ◽  
Layer Flow

In this work we study the motion of a two-dimensional incompressible flow of an electrically conducting viscoelastic fluid past an infinite porous flat plate subject to uniform suction in the presence of a transverse uniform magnetic field. The effects of the flow on the temperature of the plate are studied when the plate is thermally insulated, and when it is kept at a constant temperature that is higher than that of the free stream. A method proposed by Lighthill and Stuart is utilized in solving the problem. The effects of various parameters such as the magnetic number, the viscoelastic parameter, and the frequency of the free-stream oscillations on the flow are studied.

The magneto-hydrodynamic boundary layer in the two-dimensional steady flow past a semi-infinite flat plate. I. Uniform conditions at infinity

1963 ◽  
Vol 273 (1355) ◽  
pp. 496-508 ◽  
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Reynolds Number ◽  
Drag Coefficient ◽  
Flat Plate ◽  
Magnetic Reynolds Number ◽  
Linear Ordinary Differential Equations ◽  
Electrically Conducting ◽  
The Magnetic Field ◽  
Conditions At Infinity

The problem investigated is the flow of a viscous, electrically conducting liquid past a fixed, semi-infinite, unmagnetized but conducting flat plate. The liquid flow U and also the magnetic field H 0 at a distance from the plate are both assumed to be uniform and parallel to the plate. It is assumed that the Reynolds number R and magnetic Reynolds number R m are large enough for momentum and magnetic boundary layers to have developed. The standard boundary-layer techniques as used in the Blasius solution then apply and the problem reduces to the solution of two simultaneous non-linear ordinary differential equations. These are examined by the use of an iteration method suggested in the non ­ magnetic problem by Weyl and a solution of reasonable accuracy has been obtained for the drag coefficient. This confirms a similar result obtained in a different way by Carrier & Greenspan. The principal result of the paper is that the boundary layer thickens and drag coefficient diminishes steadily as the parameter S = µH 2 0 / 4πρU 2 increases. When S attains the finite value of unity the drag coefficient obtained here actually vanishes with the flow having been reduced to rest by the action of the magnetic field. This result might be inferred qualitatively since a finite amount of work has to be done in conveying liquid particles across the lines of magnetic force.

scholarly journals Large-eddy simulation of separation and reattachment of a flat plate turbulent boundary layer

2015 ◽  
Vol 785 ◽  
pp. 78-108 ◽  
Author(s):  
W. Cheng ◽  
D. I. Pullin ◽  
R. Samtaney
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Gradient ◽  
Flat Plate ◽  
Skin Friction ◽  
Separation Bubble ◽  
Reynolds Numbers ◽  
Wall Model ◽  
Large Eddy ◽  
Layer Flow

We present large-eddy simulations (LES) of separation and reattachment of a flat-plate turbulent boundary-layer flow. Instead of resolving the near wall region, we develop a two-dimensional virtual wall model which can calculate the time- and space-dependent skin-friction vector field at the wall, at the resolved scale. By combining the virtual-wall model with the stretched-vortex subgrid-scale (SGS) model, we construct a self-consistent framework for the LES of separating and reattaching turbulent wall-bounded flows at large Reynolds numbers. The present LES methodology is applied to two different experimental flows designed to produce separation/reattachment of a flat-plate turbulent boundary layer at medium Reynolds number $Re_{{\it\theta}}$ based on the momentum boundary-layer thickness ${\it\theta}$. Comparison with data from the first case at $Re_{{\it\theta}}=2000$ demonstrates the present capability for accurate calculation of the variation, with the streamwise co-ordinate up to separation, of the skin friction coefficient, $Re_{{\it\theta}}$, the boundary-layer shape factor and a non-dimensional pressure-gradient parameter. Additionally the main large-scale features of the separation bubble, including the mean streamwise velocity profiles, show good agreement with experiment. At the larger $Re_{{\it\theta}}=11\,000$ of the second case, the LES provides good postdiction of the measured skin-friction variation along the whole streamwise extent of the experiment, consisting of a very strong adverse pressure gradient leading to separation within the separation bubble itself, and in the recovering or reattachment region of strongly-favourable pressure gradient. Overall, the present two-dimensional wall model used in LES appears to be capable of capturing the quantitative features of a separation-reattachment turbulent boundary-layer flow at low to moderately large Reynolds numbers.

Entropy Generation for Bypass Transitional Boundary Layers

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Richard S. Skifton ◽  
Ralph S. Budwig ◽  
John C. Crepeau ◽  
Tao Xing
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Flat Plate ◽  
Entropy Generation ◽  
Boundary Layer Flow ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Transitional Region ◽  
Bypass Transition ◽  
Layer Flow

The principal purpose of this study is to understand the entropy generation rate in bypass, transitional, boundary-layer flow better. The experimental work utilized particle image velocimetry (PIV) and particle tracking velocimetry (PTV) to measure flow along a flat plate. The flow past the flat plate was under the influence of a negligible “zero” pressure gradient, followed by the installation of an adverse pressure gradient. Further, the boundary layer flow was artificially tripped to turbulence (called “bypass” transition) by means of elevated freestream turbulence. The entropy generation rate was seen to behave similar to that of published computational fluid dynamics (CFD) and direct numerical simulation (DNS) results. The observations from this work show the relative decrease of viscous contributions to entropy generation rate through the transition process, while the turbulent contributions of entropy generation rate greatly increase through the same transitional flow. A basic understanding of entropy generation rate over a flat plate is that a large majority of the contributions come within a wall coordinate less than 30. However, within the transitional region of the boundary layer, a tradeoff between viscous and turbulent dissipation begins to take place where a significant amount of the entropy generation rate is seen out toward the boundary layer edge.

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