Transient natural convection flow between vertical concentric cylinders heated/cooled asymmetrically

2018 ◽  
Vol 232 (7) ◽  
pp. 926-939 ◽  
Author(s):  
Basant K Jha ◽  
Michael O Oni
Keyword(s):  
Natural Convection ◽  
Buoyancy Force ◽  
Distribution Parameter ◽  
Convection Flow ◽  
Force Distribution ◽  
Natural Convection Flow ◽  
Transient Natural Convection ◽  
Riemann Sum ◽  
Concentric Cylinders ◽  
The Impact

This paper investigates the impact of asymmetric heating or cooling of cylinder surfaces on transient natural convection flow in between vertical concentric cylinders. The outer surface of inner cylinder is assumed to be heated with temperature greater than the cooled inner surface of the outer cylinder. Closed form expressions are obtained by using the well-known Laplace transform technique to solve the governing partial differential equations in Laplace domain, whereas the Riemann-sum approximation is used to invert to time domain. Results show that the role of buoyancy force distribution parameter is to increase temperature, velocity, skin-friction and volume flow rate for both air and water. Further, reverse flow formation can be controlled by using suitable buoyancy force distribution parameter.

scholarly journals Role of Induced Magnetic Field on Transient Natural Convection Flow in a Vertical Channel: The Riemann Sum Approximation Approach

2015 ◽  
Vol 20 (1) ◽  
pp. 65-85
Author(s):  
B.K. Jha ◽  
I. Sani
Keyword(s):  
Magnetic Field ◽  
Natural Convection ◽  
Vertical Channel ◽  
Convection Flow ◽  
Induced Magnetic Field ◽  
Natural Convection Flow ◽  
Transient Natural Convection ◽  
Riemann Sum ◽  
Laplace Transform Technique

Abstract This paper investigates the role of induced magnetic field on a transient natural convection flow of an electrically conducting, incompressible and viscous fluid in a vertical channel formed by two infinite vertical parallel plates. The transient flow formation inside the channel is due to sudden asymmetric heating of channel walls. The time dependent momentum, energy and magnetic induction equations are solved semi-analytically using the Laplace transform technique along with the Riemann-sum approximation method. The solutions obtained are validated by comparisons with the closed form solutions obtained for the steady states which have been derived separately and also by the implicit finite difference method. Graphical results for the temperature, velocity, induced magnetic field, current density, and skin-friction based on the semi-analytical solutions are presented and discussed.

Natural convection flow in a vertical micro-annulus with time-periodic thermal boundary conditions

2018 ◽  
Vol 14 (5) ◽  
pp. 1064-1081
Author(s):  
Basant Kumar Jha ◽  
Michael O. Oni
Keyword(s):  
Nusselt Number ◽  
Natural Convection ◽  
Boundary Conditions ◽  
Skin Friction ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Content Type ◽  
Thermal Boundary Conditions ◽  
The Impact ◽  
Time Periodic

PurposeThe purpose of this paper is to investigate the impact of time-periodic thermal boundary conditions on natural convection flow in a vertical micro-annulus.Design/methodology/approachAnalytical solution in terms of Bessel’s function and modified Bessel’s function of order 0 and 1 is obtained for velocity, temperature, Nusselt number, skin friction and mass flow rate.FindingsIt is established that the role of Knudsen number and fluid–wall interaction parameter is to decrease fluid temperature, velocity, Nusselt number and skin friction.Research limitations/implicationsNo laboratory practical or experiment was conducted.Practical implicationsCooling device in electronic panels, card and micro-chips is frequently cooled by natural convection.Originality/valueIn view of the amount of works done on natural convection in microchannel, it becomes interesting to investigate the effect that time-periodic heating has on natural convection flow in a vertical micro-annulus. The purpose of this paper is to examine the impact of time-periodic thermal boundary conditions on natural convection flow in a vertical micro-annulus.

scholarly journals A novel comparative case study of entropy generation for natural convection flow of proportional-Caputo hybrid and Atangana baleanu fractional derivative

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Dolat khan ◽  
Poom Kumam ◽  
Wiboonsak Watthayu
Keyword(s):  
Natural Convection ◽  
Fractional Derivative ◽  
Entropy Generation ◽  
Comparative Case Study ◽  
Convection Flow ◽  
Bejan Number ◽  
Natural Convection Flow ◽  
The Comparative Study ◽  
The Impact ◽  
First Time

AbstractThis article focused on the comparative study of entropy generation for natural convection flow of the newly proportional Caputo hybrid and Atangana baleanu fractional derivative. The governing equation is formed as the set of partial differential equations with the physical boundary conditions. The report of entropy generation is investigated for the first time for proportional–Caputo hybrid model and comparison are sorts out with generalized Atangana baleanu fractional derivative. The Bejan number is also compared for the mention fractional derivatives. Graphs show the impact of various factors on the minimization and maximizing of entropy production. The newly proportional Caputo hybrid operator has a good memory effect rather than Atangana baleanu fractional operator.

scholarly journals Transient development of MHD natural convection flow in vertical concentric annulus

2020 ◽  
Vol 9 (1) ◽  
pp. 58
Author(s):  
Basant K. Jha ◽  
Taiwo S. Yusuf
Keyword(s):  
Natural Convection ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Steady State Solution ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Approximation Approach ◽  
Riemann Sum ◽  
Laplace Transform Technique

<p>This paper examines the role of magnetic field on fully developed natural convection flow in an annulus due to symmetric of surfaces. The transport equations concerned with the model under consideration are rendered non-dimensional and transformed into the ordinary differential equation using Laplace transform technique. The solution obtained is then transformed to time domain using the Riemann-sum approximation approach. The governing equations are also solved using implicit finite difference method so as to establish the accuracy of the Riemann-sum approximation approach at transient as well as at steady state solution. The solutions obtained are graphically represented and the effects of pertinent parameters on the flow formation are investigated in detail. The Hartmann number (M), is seen to have a retarding effect on the velocity, skin-frictions and the mass flow rate. Also, skin-friction at both surfaces and the mass flow rate within the annulus are found to be directly proportional to the radii ratio (λ).</p>

A semi-analytical solution for time-dependent natural convection flow with heat generation/absorption in an annulus partially filled with porous material

2018 ◽  
Vol 14 (5) ◽  
pp. 1042-1063 ◽  
Author(s):  
Taiwo S. Yusuf ◽  
Basant K. Jha
Keyword(s):  
Natural Convection ◽  
Porous Material ◽  
Heat Generation ◽  
Constant Heat Flux ◽  
Time Dependent ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Constant Heat ◽  
Content Type ◽  
Riemann Sum

Purpose The purpose of this paper is to present a semi-analytical solution for time-dependent natural convection flow with heat generation/absorption in an annulus partially filled with porous material. Design/methodology/approach The governing partial differential equations are transformed into the ordinary differential equations using the Laplace transform technique. The exact solution obtained is inverted from the Laplace domain to time domain using the Riemann-sum approximation approach. Justification of the Riemann-sum approximation approach is achieved by comparing the values obtained with those of the implicit finite difference method at both the transient state and the steady state at large time. Findings If is found that the peak axial velocity always occur in the clear fluid region. In addition, there is an indication that heat generating fluid is desirable for optimum mass flux in the annular gap most importantly when the convection current is enhanced by constant heat flux. Originality/value In view of the amount of works done on natural convection with internal heat generation/absorption, it becomes interesting to investigate the influence of this essential activity on natural convection flow in a vertical cylinder partially filled with porous material where the outer surface of the inner cylinder is either heated isothermally or with constant heat flux.

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