Air entrapment of a neutral drop impacting onto a flat solid surface in electric fields

• DOI: 10.1017/jfm.2022.439
• Publication Date: 2022-08-04T13:18:24Z
• Authors: Yu Tian; Yanchu Liu; Zihan Peng; Chenghao Xu; Dong Ye; Yin Guan; Xinping Zhou; Weiwei Deng; YongAn Huang
• Keywords: 0103 physical sciences; 16. Peace & justice; 01 natural sciences

When a charge neutral drop impacts on flat solid substrate, small air bubble is always trapped underneath due to the lubrication pressure coming from viscous stress in squeezed film. Herein we find experimentally and numerically that process of entrapment initial contact state with substrate can be profoundly altered via an external electric field. In field, induced stresses at bottom increase drastically right before contacts which acts against pressure, resulting reduced radius size. field reaches critical value, electrical accelerates flow near generates conical tip quickly instead dimple, centre eliminating entrapment. Based dipole mirror model, dimensionless strength scales square root capillary number based viscosity. This scaling law for verified numerically. work may offer new way mitigate defects caused by inkjet printing droplet-based additive manufacturing.