Multi-Mechanism Energy Dissipation Model for Droplet Impact on Superhydrophobic Surfaces: A Comprehensive Framework Integrating  Viscous, Slip, and Contact Line Effects"

For precise predictions of droplet impact dynamics on superhydrophobic surfaces, energy dissipation modelling is inevitable. Most theories apply viscous dissipation and neglect important other sources of dissipation, including slip effects and triple line dynamics, which lead to poor estimations, particularly for hydrophobic surfaces. The present research proposes a new multi-mechanism energy dissipation model that accounts for four separate mechanisms of energy loss: viscous dissipation with slip velocity effect, Slip-induced losses at the liquid-solid interface, dissipation due to triple-line movement, and contact angle hysteresis. The model proposes a linear velocity profile, considering slip velocity and a contact angle-based weighting function to regulate triple-line effects in relation to the hydrophobicity of surfaces. Comparing the model with the experiment through high-speed camera recording of water droplets impacting inclined superhydrophobic surfaces reveals some dynamic properties of the surface. For three repetitive rebounds, the model accurately predicts dynamic contact angles between 140.0° and 144.0° and slip velocities between 0.111 and 0.158 m/s, with maximal fitting errors of less than 0.34%. Unlike a static measurement approach, this process enables estimation of slip velocity and dynamic contact angle, based on energy loss measurements, and provides valuable insights into the qualities of dynamic surface properties for different applications.