scholarly journals Numerical investigation fluid velocity and heat transfer on the stretching sheet by VIM method and optimization fluid temperature and velocity parameter by Prandtl number and viscoelastic parameter

2021 ◽  
Author(s):  
Pooya Pasha ◽  
Ali Hosin Alibak ◽  
Hossein Nabi ◽  
Farzad tat Shahdost
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Iteration Method ◽  
Stretching Sheet ◽  
Fluid Velocity ◽  
Convection Heat Transfer ◽  
Fluid Temperature ◽  
Viscoelastic Parameter ◽  
Velocity Changes ◽  
Variation Iteration Method

This study aimed at investigating the variation of heat transfer and velocity changes of the fluid flow along the vertical line on a surface drawn from both sides. In the beginning, the several parameters such as Prandtl number and viscoelastic effect evaluated for heat transfer and fluid velocity by variation Iteration method. The results were compared with the numerical method. The second part of the description relates to the use RSM method in the Design Expert software. In this paper by using the RSM method, optimized the fluid velocity and heat transfer passing from the stretching sheet. By increasing the Prandtl number, the convection heat transfer 43 % increased ratio the minimum Prandtl number. In accordance with balanced modes for Prandtl number and viscoelastic parameter and wall temperature, the best optimization occurred for fluid velocity and fluid temperature with f=0.67 and θ=0.606. The results of variation iteration method are accurate for the nonlinear solution. As the value of k increases, the value of fluid velocity indicates an increase and by increase Prandtl number, the value of Temperature decreases.

Laminar Heat Transfer in a Channel With Unsteady Flow and Wall Heating Varying With Position and Time

1963 ◽  
Vol 85 (4) ◽  
pp. 358-365 ◽  
Author(s):  
R. Siegel ◽  
M. Perlmutter
Keyword(s):  
Heat Transfer ◽  
Cross Section ◽  
Heat Production ◽  
Fluid Velocity ◽  
Isothermal Condition ◽  
Convection Heat Transfer ◽  
Channel Cross Section ◽  
Fluid Temperature ◽  
Parallel Plates ◽  
General Relations

An analysis is made of incompressible laminar forced convection heat transfer between two parallel plates that have a specified heat production to be dissipated at their surfaces. The heat production can vary in an arbitrary manner with time and position along the channel, starting from an initially isothermal condition. The fluid velocity is assumed constant over the channel cross section, but can vary with time. The variation of fluid temperature over the channel cross section is accounted for. General relations are presented in closed form and their application is illustrated by carrying out some typical examples. The results are compared with previous analyses that have assumed constant temperatures over the channel cross section and a constant heat-transfer coefficient.

Improvement Of Free Convection From Three horizontal Finned Cylinders Fixed Between Two Walls

2018 ◽  
Vol 6 (2) ◽  
pp. 98-114 ◽  
Author(s):  
Hassan K. Abdullah ◽  
Haneen H. Rahman
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Prandtl Number ◽  
Convection Heat Transfer ◽  
Constant Heat Flux ◽  
Heat Fluxes ◽  
Head Orientation ◽  
Outer Diameter ◽  
Gravitational Acceleration ◽  
Convection Heat

Improvement of  free convection heat transfer from three finned cylinders arranged at a triangle shape fixed between two walls has been investigated in this study. Three mild steel finned cylinders fixed between two walls from Pyrex glass have been used as a test rig. It has been changed the spacing between the cylinders (X/D=1,2,3 & S/D=2,4,6) and the head orientation of a triangle to the top under constant heat flux values (38, 254, 660, 1268) W/m2 and compare with case of three finned cylinders arranged in vertical array in line fixed between two wall. The experiments are carried for Rayleigh number (Ra) from (15x103 to 14 x104 ) and Prandtl  number from (0.706-0.714 ). The results indicated an increase in Nu with increasing Ra for all cylinders. Furthermore,hx and Nu increased proportionally with the increasing of cylinder spacings for all heat fluxes. Also the experimental results show the case of triangle arrangement is improvement the heat transfer more than case of vertical arrangement. Heat transfer dimensionless correlating equation is also proposed.              Nomeclature: Ax: surface area(m2), T∞: surrounding temperature(k), D: the outer diameter of fin (m), Kf: the thermal conductivity for air at film temperature(W/m.k), hx: Local convection heat transfer(W/m2.k),  Gravitational acceleration(m/s2), I: Electric current (Amp), Nu: Nusselt number, Pr: Prandtl number

Unsteady Natural Convection Heat Transfer Past a Vertical Flat Plate Embedded in a Porous Medium Saturated With Fractional Oldroyd-B Fluid

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Jinhu Zhao ◽  
Liancun Zheng ◽  
Xinxin Zhang ◽  
Fawang Liu ◽  
Xuehui Chen
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Porous Medium ◽  
Natural Convection ◽  
Prandtl Number ◽  
Fractional Derivative ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Elastic Effect

This paper investigates natural convection heat transfer of generalized Oldroyd-B fluid in a porous medium with modified fractional Darcy's law. Nonlinear coupled boundary layer governing equations are formulated with time–space fractional derivatives in the momentum equation. Numerical solutions are obtained by the newly developed finite difference method combined with L1-algorithm. The effects of involved parameters on velocity and temperature fields are presented graphically and analyzed in detail. Results indicate that, different from the classical result that Prandtl number only affects the heat transfer, it has remarkable influence on both the velocity and temperature boundary layers, the average Nusselt number rises dramatically in low Prandtl number, but increases slowly with the augment of Prandtl number. The maximum value of velocity profile and the thickness of momentum boundary layer increases with the augment of porosity and Darcy number. Moreover, the relaxation fractional derivative parameter accelerates the convection flow and weakens the elastic effect significantly, while the retardation fractional derivative parameter slows down the motion and strengthens the elastic effect.

Analytical Study of the Convection Heat Transfer From an Isothermal Wedge Surface to Fluids

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
M. Bachiri ◽  
A. Bouabdallah
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Ad Hoc ◽  
Convection Heat Transfer ◽  
Analytical Approximation ◽  
Numerical Results ◽  
Convection Heat ◽  
Governing Equations ◽  
Wedge Surface ◽  
Prandtl Numbers

In this work, we attempt to establish a general analytical approximation of the convection heat transfer from an isothermal wedge surface to fluids for all Prandtl numbers. The flow has been assumed to be laminar and steady state. The governing equations have been written in dimensionless form using a similarity method. A simple ad hoc technique is used to solve analytically the governing equations by proposing a general formula of the velocity profile. This formula verifies the boundary conditions and the equilibrium of the governing equations in the whole spatial region and permits us to obtain analytically the temperature profiles for all Prandtl numbers and for various configurations of the wedge surface. A comparison with the numerical results is given for all spatial regions and in wide Prandtl number values. A new Nusselt number expression is obtained for various configurations of the wedge surface and compared with the numerical results in wide Prandtl number values.

Radiation and Convection Heat Transfer in a Porous Bed

1968 ◽  
Vol 90 (1) ◽  
pp. 51-54 ◽  
Author(s):  
W. A. Beckman
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Collection Efficiency ◽  
Convection Heat Transfer ◽  
Heat Fluxes ◽  
Fluid Temperature ◽  
Radiation Heat ◽  
Radiation Heat Flux ◽  
Flowing Fluid ◽  
Porous Bed

The one-dimensional steady-state temperature distribution within an isotropic porous bed subjected to a collimated and/or diffuse radiation heat flux and a transparent flowing fluid has been determined by numerical methods. The porous bed was assumed to be nonscattering and to have a constant absorption coefficient. Part of the radiation absorbed by the porous bed is reradiated and the remainder is transferred to the fluid by convection. Due to the assumed finite volumetric heat transfer coefficient, the bed and fluid have different temperatures. A bed with an optical depth of six and with a normal incident collimated radiation heat flux was investigated in detail. The radiation incident on the bed at the fluid exit was assumed to originate from a black surface at the fluid exit temperature. The investigation covered the range of incident diffuse and collimated radiation heat fluxes expected in a nonconcentrating solar energy collector. The results are presented in terms of a bed collection efficiency from which the fluid temperature rise can be calculated.

scholarly journals MHD three dimensional flow of Oldroyd-B nanofluid over a bidirectional stretching sheet: DTM-Padé Solution

2019 ◽  
Vol 8 (1) ◽  
pp. 744-754 ◽  
Author(s):  
Sumit Gupta ◽  
Sandeep Gupta
Keyword(s):  
Brownian Motion ◽  
Differential Equations ◽  
Prandtl Number ◽  
Comparative Study ◽  
Stretching Sheet ◽  
Fluid Velocity ◽  
Deborah Number ◽  
Motion Parameter ◽  
Physical Parameters ◽  
Brownian Motion Parameter

Abstract Current article is devoted with the study of MHD 3D flow of Oldroyd B type nanofluid induced by bi-directional stretching sheet. Expertise similarity transformation is confined to reduce the governing partial differential equations into ordinary nonlinear differential equations. These dimensionless equations are then solved by the Differential Transform Method combined with the Padé approximation (DTM-Padé). Dealings of the arising physical parameters namely the Deborah numbers β1 and β2, Prandtl number Pr, Brownian motion parameter Nb and thermophoresis parameter Nt on the fluid velocity, temperature and concentration profile are depicted through graphs. Also a comparative study between DTM and numerical method are presented by graph and other semi-analytical techniques through tables. It is envisage that the velocity profile declines with rising magnetic factor, temperature profile increases with magnetic parameter, Deborah number of first kind and Brownian motion parameter while decreases with Deborah number of second kind and Prandtl number. A comparative study also visualizes comparative study in details.

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