A viscously dissipated Blasisus boundary layer flow with variable thermo-physical properties: An entropy generation study

Author(s):  
Mair Khan ◽  
T. Salahuddin ◽  
Mohamed Altanji
2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Richard S. Skifton ◽  
Ralph S. Budwig ◽  
John C. Crepeau ◽  
Tao Xing

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.


2017 ◽  
Vol 139 (10) ◽  
Author(s):  
M. I. Afridi ◽  
M. Qasim ◽  
O. D. Makinde

An entropy generation analysis of steady boundary layer flow of viscous fluid with variable properties over an exponentially stretching sheet is presented. The basic nonlinear partial differential equations that govern the flow are reduced to ordinary differential equations by using appropriate transformations. Numerical solutions are obtained by using shooting technique along with Runge–Kutta method. Expressions for the dimensionless volumetric entropy generation rate (NG) and Bejan number are also obtained. The effects of different dimensionless emerging parameters on entropy generation number (NG) and Bejan number (Be) are investigated graphically in detail.


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