Analysis of unsteady force convection flows on irregular boundary over a diverging channel

Heat Transfer ◽  
2020 ◽  
Author(s):  
Iyyappan Govindhasamy ◽  
Abhishek K. Singh ◽  
Satyajit Roy
Keyword(s):  
Force Convection ◽  
Irregular Boundary ◽  
Unsteady Force ◽  
Diverging Channel

MHD flows on irregular boundary over a diverging channel with viscous dissipation effect

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Iyyappan G. ◽  
Abhishek Kumar Singh
Keyword(s):  
Heat Transfer ◽  
Finite Difference ◽  
Difference Scheme ◽  
Skin Friction ◽  
Viscous Dissipation ◽  
Finite Difference Scheme ◽  
Uniform Mesh ◽  
Irregular Boundary ◽  
Content Type ◽  
Diverging Channel

Purpose The purpose of this paper is to analyse the force convection laminar boundary layer flow on irregular boundary in diverging channel with the presence of magnetic field effects. Effects of various fluid parameters such as suction/injection, viscous dissipation, magnetic parameter and heat source/sink on velocity and temperature profiles are numerically analyzed. Moreover, numerically investigated on skin-friction and heat transfer coefficients when suction/injection occur. Design/methodology/approach The governing coupled partial differential equations are transformed to dimensionless form using non-similarity transformations. The non-dimensional partial differential equations are linearized by quasi-linearization technique and solved by varga's algorithm with numerical finite difference scheme on a non-uniform mesh. Findings The computation results are presented in terms of temperature, heat transfer and skin friction coefficients; these are useful for determining surface heat requirements. It was found that, in finite difference scheme for non-uniform mesh with quasi-linearization technique method gives smoothness of solution compared to finite difference scheme for uniform mesh, and this evidence is graphically represented in Figure 2. Originality/value The impacts of viscous dissipation (Ec) and magnetic parameter (Ha) on temperature profiles, skin friction and heat transfer are analyzed, which determine the heat generation/absorption to ensure the MHD flow of the laminar boundary layer on irregular boundary over a diverging channel.

Study of converging-diverging channel induced convective mass transport in a proton exchange membrane fuel cell

2021 ◽  
Vol 237 ◽  
pp. 114095
Author(s):  
Felipe Mojica ◽  
Md Azimur Rahman ◽  
Mrittunjoy Sarker ◽  
Daniel S. Hussey ◽  
David L. Jacobson ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Mass Transport ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Diverging Channel ◽  
Exchange Membrane

scholarly journals Quantum Holography in a Graphene Flake with an Irregular Boundary

2018 ◽  
Vol 121 (3) ◽  
Author(s):  
Anffany Chen ◽  
R. Ilan ◽  
F. de Juan ◽  
D. I. Pikulin ◽  
M. Franz
Keyword(s):  
Graphene Flake ◽  
Irregular Boundary

Flow dynamics and enhanced mixing in a converging–diverging channel

2016 ◽  
Vol 807 ◽  
pp. 167-204 ◽  
Author(s):  
S. W. Gepner ◽  
J. M. Floryan
Keyword(s):  
Three Dimensional ◽  
Travelling Wave ◽  
Flow Dynamics ◽  
Streamwise Vortices ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Wave Instability ◽  
Unsteady Separation ◽  
Flow Stabilization ◽  
Diverging Channel

An analysis of flows in converging–diverging channels has been carried out with the primary goal of identifying geometries which result in increased mixing. The model geometry consists of a channel whose walls are fitted with spanwise grooves of moderate amplitudes (up to 10 % of the mean channel opening) and of sinusoidal shape. The groove systems on each wall are shifted by half of a wavelength with respect to each other, resulting in the formation of a converging–diverging conduit. The analysis is carried out up to Reynolds numbers resulting in the formation of secondary states. The first part of the analysis is based on a two-dimensional model and demonstrates that increasing the corrugation wavelength results in the appearance of an unsteady separation whose onset correlates with the onset of the travelling wave instability. The second part of the analysis is based on a three-dimensional model and demonstrates that the flow dynamics is dominated by the centrifugal instability over a large range of geometric parameters, resulting in the formation of streamwise vortices. It is shown that the onset of the vortices may lead to the elimination of the unsteady separation. The critical Reynolds number for the vortex onset initially decreases as the corrugation amplitude increases but an excessive increase leads to the stream lift up, reduction of the centrifugal forces and flow stabilization. The flow dynamics under such conditions is again dominated by the travelling wave instability. Conditions leading to the formation of streamwise vortices without interference from the travelling wave instability have been identified. The structure and the mixing properties of the saturated states are discussed.

On the unsteady inviscid force on cylinders and spheres in subcritical compressible flow

2008 ◽  
Vol 366 (1873) ◽  
pp. 2161-2175 ◽  
Author(s):  
M Parmar ◽  
A Haselbacher ◽  
S Balachandar
Keyword(s):  
Mach Number ◽  
Compressible Flow ◽  
Propagation Speed ◽  
Added Mass ◽  
The Body ◽  
Mass Force ◽  
Unsteady Force ◽  
Mass Coefficient ◽  
Added Mass Coefficient ◽  
Cylinders And Spheres

The unsteady inviscid force on cylinders and spheres in subcritical compressible flow is investigated. In the limit of incompressible flow, the unsteady inviscid force on a cylinder or sphere is the so-called added-mass force that is proportional to the product of the mass displaced by the body and the instantaneous acceleration. In compressible flow, the finite acoustic propagation speed means that the unsteady inviscid force arising from an instantaneously applied constant acceleration develops gradually and reaches steady values only for non-dimensional times c ∞ t / R ≳10, where c ∞ is the freestream speed of sound and R is the radius of the cylinder or sphere. In this limit, an effective added-mass coefficient may be defined. The main conclusion of our study is that the freestream Mach number has a pronounced effect on both the peak value of the unsteady force and the effective added-mass coefficient. At a freestream Mach number of 0.5, the effective added-mass coefficient is about twice as large as the incompressible value for the sphere. Coupled with an impulsive acceleration, the unsteady inviscid force in compressible flow can be more than four times larger than that predicted from incompressible theory. Furthermore, the effect of the ratio of specific heats on the unsteady force becomes more pronounced as the Mach number increases.

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