A fractal model for gas slippage factor in porous media in the slip flow regime

2013 ◽  
Vol 87 ◽  
pp. 209-215 ◽  
Author(s):  
Qian Zheng ◽  
Boming Yu ◽  
Yonggang Duan ◽  
Quantang Fang
Author(s):  
Ruina Xu ◽  
Peixue Jiang

The effect of particle diameter on the air flow characteristics in various micro-porous media test sections was studied experimentally and numerically. The test sections were made of bronze particles with average diameters of 200 μm, 125 μm, 90 μm and 40 μm. The experimentally measured friction factors in the porous media with average diameters of 200 μm and 125 μm agree well with the known correlation. However, the experimental values for the friction factors in the micro-porous media with 90 μm a and 40 μm average diameters are much less than the known correlation. Also, the differences between the experimental results and the known correlation increase with decreasing average particle diameter. Numerical simulations of the air flow in micro-porous media including rarefaction were performed using the CFD code FLUENT 6.1 to predict the pressure drop characteristics in the four test sections. The calculated friction factors for the non-slip flow regime in the micro-porous media agree well with the known correlation and the experimental data. The numerically predicted friction factors for the slip flow regime in the micro-porous media with 90 μm and 40 μm diameter particles were less than the known correlation and close to the experimental data. The results show that rarefaction effects occur in air flows in the micro-porous media with particle diameters less than 90 a and that numerical calculations with velocity slip on the boundary can simulate the slip flows in micro-porous media.


2016 ◽  
Vol 13 (1) ◽  
pp. 51-62 ◽  
Author(s):  
Narasu Siva Kumar ◽  
Rushi Kumar ◽  
A. G. Vijaya Kumar

The present study investigates an analytical solution of free convective unsteady fluid flow in presence of thermal diffusion and chemical reaction effects past a vertical porous plate with heat source dependent in slip flow regime. The plate is assumed to move with a constant velocity in the direction of fluid flow, while free stream velocity is assumed to follow exponentially increasing small perturbation law. The velocity, temperature and concentration profiles are presented graphically for different values of the parameters entering into the problem. Finally the effects of pertinent parameters on the skin friction coefficient, Nusselt number and Sherwood numbers distributions are derived and have shown through graphs and tables by using perturbation technique.


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