Water entry through particle-stabilized foamy surfaces

Stabilized foams have many applications in oil recovery, food and pharmaceutical production, and foam products. In nature, sea foam (more commonly known as white caps) reflect solar rays and radiation. Current literature shows that foams can be stabilized by surfactants and microplastics, both of which are present at the sea surface. However, the effects of the microplastics on foam height and lifetime and the effects of the foam on water entry activity and cavitation are not well studied. Cavities decrease drag experienced by an object entering a liquid via a gas-liquid interface and are thus studied with the aim of understanding the fluid dynamic mechanism and what properties of the impacting object induces and effects cavitation. While studies have shown that the presence of surfactant-stabilized foams and penetrable fabrics can induce cavitation below the critical impact velocity, little is known about the effects of microplastics and microplastic stabilized foams on the formation of a cavity. With this work, we endeavor to characterize how the stabilized foam with and without particulates alters the cavity and the critical impact speed for sphere impacts in the range Re = 1.5 x10⁴ – 3.3 x 10⁴, We = 7.3 x 10² – 7.7 x 10³, Bo = 2.5 – 5.5 . We hypothesize that while the stabilized foam will lower the critical impact speed, the particles will cause a nonuniform wetting of the impacting sphere by delaying the impact in locations on the sphere where it impacts the particulates first, thus creating an asymmetric cavity.