Numerical Investigation on the Influence of Gas Area Fraction on Developing Flow in a Pipe Containing Superhydrophobic Transverse Grooves

Kok Hwa Yu; Yew Heng Teoh; Mohd Azmi Ismail; Chih Fang Lee; Farzad Ismail

Authors

Kok Hwa Yu School of Mechanical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Penang, Malaysia
Yew Heng Teoh School of Mechanical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Penang, Malaysia
Mohd Azmi Ismail School of Mechanical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Penang, Malaysia
Chih Fang Lee School of Mechanical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Penang, Malaysia
Farzad Ismail School of Mechanical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Penang, Malaysia

Keywords:

Entrance length , water-repellent , surface roughness, laminar flow , wall slip

Abstract

This study presents a numerical investigation on the entrance length for developing flow in a pipe having alternating superhydrophobic grooves and ribs arranged transversely to the flow direction. Flows at low Reynolds number (i.e., = 1) over superhydrophobic transverse grooves of = 0.1 are considered. The influences of superhydrophobic surfaces on radial velocity profile development, centerline velocity distribution and hydrodynamic entrance length estimation are examined. Numerical results show that the hydrodynamic entrance length arising from flow over superhydrophobic transverse grooves are longer as compared to that of smooth wall. It is also found that the resulted entrance length is directly influence by the relative surface area occupied by grooves (i.e., gas area fraction). When the gas area fraction is larger, it would yield an increase in the hydrodynamic entrance length.