  In the present study, we delineate the effect of introducing flow
obstructions on streaming potential and energy conversion efficiency in a
narrow fluidic confinement taking into consideration the wall hydrodynamic
slip, finite ionic size, and local permittivity variation effects. We consider
two types of the geometric pattern of flow obstacle between which regular
pattern turns out to be more effective. It is observed that, implementing
structured flow obstacles of radii greater than 10% of channel height and
charge density ratio (charge density of flow obstacle surface to that of
channel wall) greater than or equal to 9 renders significant enhancement of
power generation efficiency. On the other hand, it is effective to operate at a
charge density ratio~1 for obstacles radii less than or equal to 10% of channel
height. An effective normalized pitch length of magnitude 0.6 or above has to
be maintained in order to obtain optimum energy conversion efficiency. We found
that implementation of charged flow obstacle causes a significant enhancement
of energy conversion efficiency (~18% with regular pattern) comparing to planar
slit channel (~4%) without considering wall hydrodynamic slip and steric
effects. Introducing finite ionic size and wall hydrodynamic slip effect,
pertinent to flows in narrow confinement, leads to further enhancement in
electrokinetic energy conversion efficiency.
