Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.
One of important phenomenon's in micro and nano-devices
is slippage. The concept of slip length has been introduced to
compute slip at the solid surfaces. A large slip length decreases
dissipation at the surfaces and results in changing pressure
drop. In this paper, the effect of roughness periodicity has been
studied, which deals with distances between corrugations, on
velocity profile and slip length variations by molecular
dynamics simulations. To have a perfect analysis, the channel
walls was chosen to be rough and after that by increasing the
distances between corrugations which result in increasing
periodicity of roughness, its effect on variation of velocity
profiles undergoing Poiseuille flow was investigated. Also, the
slip length in each simulation which shows the magnitude of
slippage was calculated. As the results showed, when
roughness periods increased, velocity profiles were found to be
the same as flat channel’s profile and slip length decreases. The
outcomes also reveal a non-linear dependency of the slip length
magnitude on the roughness period. Slip length profiles also
showed that slip decreases by increasing the height of the nanochannel,
because solid-fluid interface effects will disappear in
channels with more height and slip length would have greater
magnitudes as a result.
