  Materials with periodic architectures exhibit many beneficial characteristics
such as high specific stiffness thanks to the material placement along the
stress paths and the nano-scale strength amplification achieved through the use
of hierarchical architectures. Recently, the porosity of architectured
materials was leveraged to increase the efficiency of compact heat exchangers,
and their internal aerodynamics was studied. However, their performance on
external aerodynamics applications is generally assumed to be detrimental.
Here, we demonstrate that exposing 3D lattice material to the external flow
reduced the drag of a circular cylinder when placed at carefully selected
angular locations. We tested two configurations with the lattice material
installed at the windward and leeward regions. On the one hand, the windward
configuration showed a strong Re dependency, with a drag reduction of up to 45%
at Re=11E4. On the other hand, the lattice material in the leeward region
reduced the drag by 25% with weak Re dependency. Alterations of the lattice
material topology had a noticeable effect on the drag reduction in both cases.
Adding aerodynamic features to the already proven beneficial structural
properties of 3D lattice materials might aid in the development of low-powered
automotive, naval, and aerospace vehicles.
