Spreading and penetration dynamics of ink drops upon impacting a permeable textile

Abstract

The interaction between ink drops and permeable textiles is complicated but crucial for textile inkjet printing. To address this, a modified model was developed in the current research by employing the volume of fluid method. The capillary force and the flow resistance were taken into account in the momentum equation, enabling the simulation of both spreading and penetration of ink drops upon impacting a textile. The evolutions of drop morphology, pressure distribution, and velocity field were investigated. An interesting finding is the entrapment of air bubbles with higher internal pressure at the intersection of warp and weft yarns due to the flow difference in the axial and radial directions of a yarn. To explore the influence of critical factors, parametric study was further conducted by varying impact velocity, drop diameter, and ink viscosity. Results show that increasing impact velocity enhances both the spreading and penetration of ink drops. The increase in drop diameter leads to a larger maximum spreading ratio but a smaller penetration ratio, as the penetration dynamics in the numerical model is independent of drop size. Additionally, ink drops with a higher viscosity display reduced spreading and penetration within the textile, primarily due to the rise in flow resistance and energy dissipation.