Laminar mixed convection boundary layer flow induced by a permeable surface stretched with prescribed skin friction boundary conditions

• Main Authors: Mohamed Ali, Abdullah Alabdulkarem
• Format: Article
• Language: English
• Published: SAGE Publishing 2015-09-01
• Series: Advances in Mechanical Engineering
• Online Access: https://doi.org/10.1177/1687814015605747

The mixed laminar boundary layer flow and heat transfer on a permeable stretched surface moving with prescribed skin friction are studied. Three major cases, which correspond to complete similarity solutions, are considered. The cases are combinations of power law indices n and m representing temperature and skin friction distributions, respectively. The first case ( n  = 0, m  = 0.5) corresponds to isothermal stretched surface with skin friction at the surface scales as x 1/4 . The second case ( n  = 1, m  = 1) is a linear temperature and skin friction distribution along the vertical stretched surface. The third case ( n  = −1, m  = 0) represents inverse temperature variation along the surface with prescribed skin friction of the order of x −1/2 . Similarity solutions are obtained for the surface stretched in a stagnant air with Prandtl number = 0.72. The effect of suction/injection velocity ( f w ) and the buoyancy parameter ( λ ) is studied in detail. The results show that the heat transfer coefficient along the surface is enhanced for assisting flow ( λ  > 0) at any value of f w for the first and second cases, while it is reduced for the third case. However, the opposite is true for the opposing flow ( λ  < 0). Furthermore, suction enhances the heat transfer coefficient, whereas injection degrades it at any fixed λ for the first and second prescribed skin friction boundary conditions, and the opposite is true for the third case.