TY - GEN

T1 - Numerical study of skin friction coefficient and reattachment length for a slip flow encountered in a partaially blocked channel

AU - Abu-Nada, Eiyad

AU - Al-Sarkhi, Abdelsalam

PY - 2004

Y1 - 2004

N2 - The current research investigates the effect of Reynolds number and Knudsen number on the coefficient of skin friction and reattachment length for a micro-scale fluid flow over a step mounted on a lower wall of a micro-channel. Five Reynolds numbers are studied Re = 1, 10, 25, 50, and 75 and the Knudsen number is varied from 1×10-3 to 0.1. Finite difference method with non-uniform grid is used to solve the incompressible Navier Stokes equations accompanied with velocity slip boundary condition. As Knudsen number (Kn) decreases the magnitude of modified local shear stress (1/2Cf Re), on the upper wall of the channel, increases. In the circulation zone behind the step and for the case of high Reynolds number (Re = 50 and Re = 75) the modified local shear stress increases as Knudsen number increases. Results show that the modified total skin friction (1/2CD Re) decreases as the Knudsen number increases. The modified total skin friction drops significantly with Knudsen number for Kn >=1×10-2. However, (1/2 C D Re) is relatively independent of Knudsen number for Kn <1×10-2. Finally, for 1×10-2 < Kn < 0.1, as Knudsen number increase the reattachment length increases.

AB - The current research investigates the effect of Reynolds number and Knudsen number on the coefficient of skin friction and reattachment length for a micro-scale fluid flow over a step mounted on a lower wall of a micro-channel. Five Reynolds numbers are studied Re = 1, 10, 25, 50, and 75 and the Knudsen number is varied from 1×10-3 to 0.1. Finite difference method with non-uniform grid is used to solve the incompressible Navier Stokes equations accompanied with velocity slip boundary condition. As Knudsen number (Kn) decreases the magnitude of modified local shear stress (1/2Cf Re), on the upper wall of the channel, increases. In the circulation zone behind the step and for the case of high Reynolds number (Re = 50 and Re = 75) the modified local shear stress increases as Knudsen number increases. Results show that the modified total skin friction (1/2CD Re) decreases as the Knudsen number increases. The modified total skin friction drops significantly with Knudsen number for Kn >=1×10-2. However, (1/2 C D Re) is relatively independent of Knudsen number for Kn <1×10-2. Finally, for 1×10-2 < Kn < 0.1, as Knudsen number increase the reattachment length increases.

KW - Flow over a step

KW - Knudsen number

KW - Micro-channels

KW - Velocity slip boundary condition

UR - http://www.scopus.com/inward/record.url?scp=4544268593&partnerID=8YFLogxK

M3 - Conference contribution

AN - SCOPUS:4544268593

SN - 0791841642

T3 - Proceedings of the Second International Conference on Microchannels and Minichannels (ICMM2004)

SP - 313

EP - 318

BT - Proceedings of the Second International Conference on Microchannels and Minichannels (ICMM2004)

A2 - Kandlikar, S.G.

A2 - Celata, G.P.

A2 - Nishio, S.

A2 - Stephan, P.

A2 - Thonon, B.

T2 - Proceedings of the Second International Conference on Microchannels and Minichannels (ICMM2004)

Y2 - 17 June 2004 through 19 June 2004

ER -