Measurement and Enhancement of Coalescence-Induced Droplet Jumping in the V‑Shaped Superhydrophobic Trench with a Curved Ridge

Coalescence-induced droplet jumping demonstrates significant
potential
for diverse applications. However, current studies on enhancing and
regulating droplet jumping largely focus on specific droplet locations
and enhancement structures, significantly restricting their broader
applications. This study introduces a V-shaped superhydrophobic trench
with a curved ridge to enhance and control droplet coalescence jumping
and directional transfer. Experimentally, a dimensionless jumping
velocity (Vj* ≈
0.69) and energy conversion efficiency (η ≈ 42.13%) were
achieved, representing about 111.63% improvement in energy conversion
efficiency compared to the V-shaped trench and an 879.77% increase
relative to planar superhydrophobic surfaces, with a jumping angle
of 66°. Numerical simulations and experiments revealed that the
curved ridge enhances droplet coalescence jumping velocity and enables
directional control by redirecting velocity vectors and minimizing
viscous loss during coalescence. Additionally, the effects of ridge
length, height, width, and opening angle on droplet coalescence jumping
were analyzed via numerical simulations, offering theoretical support
and technical guidance for practical applications. The coalescence
jumping of droplets with unequal sizes on curved ridge structures
was also studied, demonstrating that droplets with radius ratios below
0.66 can bounce off trench surfaces, confirming the structure’s
general applicability. This study further proposes a droplet velocity
measurement method integrating target detection and trajectory fitting,
achieving efficient and precise droplet velocity determination.