Methods for Controlling Vorticity Generation at the Triple Contact Line for Wake and Drag Mitigation: An Analytical and Experimental Investigation

In previous investigations, the moving contact line has been reported as a significant source of vorticity. In the context of ship hydrodynamics, this subject is of significant interest as vorticity generated by the countless bubbles along a ship hull likely contribute to increased drag and wake signatures. In order to understand these phenomena better and potentially increase ship efficiency and stealth, we conduct an analytical and experimental investigation of the moving contact line. Using the Stokes flow assumptions, a vorticity dipole is observed at the moving contact line. As the contact angle is increased, the vorticity flux from the corner singularity is predicted to decrease by several orders of magnitude. Experimental investigations are conducted using micro Particle Image Velocimetry (μ-PIV). Velocity fields show that increasing the contact angle using a hydrophobic coating can reduce the average vorticity near the contact line by 50%. For future mitigation of ship drag and wake signatures, we demonstrate that fluid injection near the contact line coupled with contact angle manipulation can reduce the local vorticity flux and reduce the total circulation to zero.