Flow and Heat Transfer of Jeffrey Fluid Over a Continuously Moving Surface With a Parallel Free Stream

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
T. Hayat ◽  
Z. Iqbal ◽  
M. Mustafa ◽  
S. Obaidat
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Free Stream ◽  
Deborah Number ◽  
Jeffrey Fluid ◽  
Stream Velocity ◽  
Moving Surface ◽  
Flow And Heat Transfer

This communication studies the flow and heat transfer characteristics over a continuously moving surface in the presence of a free stream velocity. The Jeffrey fluid is treated as a rheological model. The series expressions of velocity and temperature fields are constructed by applying the homotopy analysis method (HAM). The influence of emerging parameters such as local Deborah number (β), the ratio of relaxation and retardation times (λ2), the Prandtl number (Pr), and the Eckert number (Ec) on the velocity and temperature profiles are presented in the form of graphical and tabulated results for different values of λ. It is found that the boundary layer thickness is an increasing function of local Deborah number (β). However, the temperature and thermal boundary layer thickness decreases with the increasing values of local Deborah number (β).

scholarly journals Hydromagnetic flow and heat transfer over a bidirectional stretching surface in a porous medium

2011 ◽  
Vol 15 (suppl. 2) ◽  
pp. 205-220 ◽  
Author(s):  
Iftikhar Ahmad ◽  
Manzoor Ahmed ◽  
Zaheer Abbas ◽  
Muhammad Sajid
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Flux ◽  
Porous Medium ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Mhd Flow ◽  
Heat Transfer Analysis ◽  
Flow And Heat Transfer ◽  
Bidirectional Stretching

In this study, we present a steady three-dimensional magnetohydrodynamic (MHD) flow and heat transfer characteristics of a viscous fluid due to a bidirectional stretching sheet in a porous medium. The heat transfer analysis has been carried out for two heating processes namely (i) the prescribed surface temperature (PST) and (ii) prescribed surface heat flux (PHF). In addition the heat transfer rate varies along the surface. The similarity solution of the governing boundary layer partial differential equations is developed by employing homotopy analysis method (HAM). The quantities of interest are velocity, temperature, skin-friction and wall heat flux. The results obtained are presented through graphs and tabular data. It is observed that both velocity and boundary layer thickness decreases by increasing the porosity and magnetic field. This shows that application of magnetic and porous medium cause a control on the boundary layer thickness. Moreover, the results are also compared with the existing values in the literature and found in excellent agreement.

scholarly journals Unsteady flow and heat transfer of Jeffrey fluid over a stretching sheet

2014 ◽  
Vol 18 (4) ◽  
pp. 1069-1078 ◽  
Author(s):  
Tasawar Hayat ◽  
Zahid Iqbal ◽  
Meraj Mustafa ◽  
Ahmed Alsaedi
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Numerical Solutions ◽  
Analytic Solutions ◽  
Momentum Equation ◽  
Elastic Parameter ◽  
Deborah Number ◽  
Jeffrey Fluid ◽  
Dimensionless Energy ◽  
Flow And Heat Transfer

The boundary layer flow and heat transfer of an incompressible Jeffrey fluid have been investigated. The analytic solutions of the arising differential system have been computed by homotopy analysis method (HAM). The dimensionless expressions for wall shear stress and surface heat transfer are also derived. Exact solutions of the momentum equation and numerical solutions of the dimensionless energy equations have been obtained for the steady-state case. The results indicate an increase in the velocity and the boundary layer thickness by increasing the elastic parameter (Deborah number) for a Jeffrey fluid.

Effect of Free-Stream Velocity Definition on Boundary Layer Thickness and Losses in Centrifugal Compressors

2017 ◽  
Author(s):  
Jonna Tiainen ◽  
Ahti Jaatinen-Värri ◽  
Aki Grönman ◽  
Teemu Turunen-Saaresti ◽  
Jari Backman
Keyword(s):  
Boundary Layer ◽  
Layer Thickness ◽  
Centrifugal Compressor ◽  
Boundary Layer Thickness ◽  
Free Stream ◽  
Compressor Blade ◽  
Free Stream Velocity ◽  
Wake Flow ◽  
Stream Velocity ◽  
Centrifugal Compressors

The estimation of boundary layer losses requires the accurate specification of the free-stream velocity, which is not straightforward in centrifugal compressor blade passages. This challenge stems from the jet-wake flow structure, where the free-stream velocity between the blades cannot be clearly specified. In addition, the relative velocity decreases due to adverse pressure gradient. Therefore, the common assumption of a single free-stream velocity over the blade surface might not be valid in centrifugal compressors. Generally in turbomachinery, the losses in the blade cascade boundary layers are estimated e.g. with different loss co-efficients, but they often rely on the assumption of a uniform flow field between the blades. To give guidelines for the estimation of the mentioned losses in highly distorted centrifugal compressor flow fields, this paper discusses the difficulties in the calculation of the boundary layer thickness in the compressor blade passages, compares different free-stream velocity definitions, and demonstrates their effect on estimated boundary layer losses. Additionally, a hybrid method is proposed to overcome the challenges of defining a boundary layer in centrifugal compressors.

Flow and heat transfer to Sisko fluid with partial slip

2016 ◽  
Vol 94 (8) ◽  
pp. 724-730 ◽  
Author(s):  
Masood Khan
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Differential Equations ◽  
Layer Thickness ◽  
Analytical Solutions ◽  
Boundary Layer Thickness ◽  
Velocity Slip ◽  
Partial Slip ◽  
Exact Analytical Solutions ◽  
Flow And Heat Transfer

In this paper we study the partial slip effects on the flow and heat transfer of an incompressible non-Newtonian fluid over a nonlinear stretching sheet. The velocity slip boundary condition based on the Sisko constitutive fluid model is introduced. Suitable dimensionless variables are used to convert the governing partial differential equations into ordinary differential equations. Numerical solutions of these equations are obtained by the Runge–Kutta Fehlberg method. Additionally, the exact analytical solutions are presented in some special cases. The computational results for the velocity, temperature, skin-friction coefficient, and Nusselt number are presented in graphical and tabular forms. To validate the numerical results obtained, a comparison is made with the exact analytical solutions. The analysis of the results obtained shows that enhancement in the velocity slip parameter reduces the velocity as well as the momentum boundary layer thickness. However, quite the opposite is true with the temperature and corresponding thermal boundary layer thickness.

Boundary Layer Closure and Heat Transfer in Constant Base Pressure and Simple Wave Guns

1978 ◽  
Vol 100 (4) ◽  
pp. 690-696 ◽  
Author(s):  
A. D. Anderson ◽  
T. J. Dahm
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Method Of Characteristics ◽  
Simple Wave ◽  
Momentum Equation ◽  
Base Pressure ◽  
Two Dimensional ◽  
The Method Of Characteristics

Solutions of the two-dimensional, unsteady integral momentum equation are obtained via the method of characteristics for two limiting modes of light gas launcher operation, the “constant base pressure gun” and the “simple wave gun”. Example predictions of boundary layer thickness and heat transfer are presented for a particular 1 in. hydrogen gun operated in each of these modes. Results for the constant base pressure gun are also presented in an approximate, more general form.

Freestream Flow Effects on Film Effectiveness and Heat Transfer Coefficient Augmentation for Compound Angle Shaped Holes

2017 ◽  
Author(s):  
Joshua B. Anderson ◽  
John W. McClintic ◽  
David G. Bogard ◽  
Thomas E. Dyson ◽  
Zachary Webster
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Layer Thickness ◽  
Film Cooling ◽  
Gas Turbines ◽  
Boundary Layer Thickness ◽  
Adiabatic Effectiveness ◽  
Compound Angle

The use of compound-angled shaped film cooling holes in gas turbines provides a method for cooling regions of extreme curvature on turbine blades or vanes. These configurations have received surprisingly little attention in the film cooling literature. In this study, a row of laid-back fanshaped holes based on an open-literature design, were oriented at a 45-degree compound angle to the approaching freestream flow. In this study, the influence of the approach flow boundary layer thickness and character were experimentally investigated. A trip wire and turbulence generator were used to vary the boundary layer thickness and freestream conditions from a thin laminar boundary layer flow to a fully turbulent boundary layer and freestream at the hole breakout location. Steady-state adiabatic effectiveness and heat transfer coefficient augmentation were measured using high-resolution IR thermography, which allowed the use of an elevated density ratio of DR = 1.20. The results show adiabatic effectiveness was generally lower than for axially-oriented holes of the same geometry, and that boundary layer thickness was an important parameter in predicting effectiveness of the holes. Heat transfer coefficient augmentation was highly dependent on the freestream turbulence levels as well as boundary layer thickness, and significant spatial variations were observed.

scholarly journals Prediction of Heat Transfer From Laminar Boundary Layers, With Emphasis on Large Free-Stream Velocity Gradients and Highly Cooled Walls

1966 ◽  
Vol 88 (3) ◽  
pp. 249-256 ◽  
Author(s):  
L. H. Back ◽  
A. B. Witte
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Shear Stress ◽  
Velocity Gradient ◽  
Free Stream ◽  
Variable Density ◽  
Similarity Solutions ◽  
Free Stream Velocity ◽  
Stream Velocity ◽  
Gradient Parameter

Laminar boundary-layer heat transfer and shear-stress predictions from existing similarity solutions are extended in an approximate way to perfect gas flows with a large free-stream velocity gradient parameter β and variable density-viscosity product ρμ across the boundary layer resulting from a highly cooled wall. The dimensionless enthalpy gradient at the wall gw′, to which the heat flux is related, is found not to vary appreciably with β. Thus the application of similarity solutions on a local basis to predict heat transfer from accelerated flows to an arbitrary surface may be a reasonable approximation involving a minimum amount of calculation time. Unlike gw′, the dimensionless velocity gradient at the wall fw″, to which the shear stress is related, is strongly dependent on β.

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