the surface textures show a power law scaling FN Ω with respect
to angular velocity (i.e. linear scaling with sign depending on
sliding direction), suggesting that the measured normal forces are
produced by viscous effects rather than inertia or cavitation.
Finally, we showed that the effective friction coefficient is lowered
through the use of asymmetric surface textures, and for the textures
tested is lowest for the asymmetric texture with bottom
angle β¼5.3° at a gap height h¼269 μm. The analysis of the
effective friction coefficient also suggests that there is an optimal β
value for decreasing friction with asymmetric textures, and the
optimal value of β depends on the operational gap height