Numerical study of three-dimensional droplet impact on a flowing liquid film in annular two-phase flow

- 3D droplet deposition process in annular flow is studied in detail.
- 3D simulation of droplet impacting on flowing liquid film with a shallow angle.
- Atmospheric and high pressure conditions are taken into account for two cases.
- A new CV-FE method is employed for 3D interfacial flows with surface tension.
- The numerical framework also features an anisotropic adaptive mesh algorithm.

Annular flow with liquid entrainment occurs in a wide variety of two-phase flow system. A novel control volume finite element method with adaptive unstructured meshes is employed here to study three-dimensional droplet deposition process in annular two-phase flow. The numerical framework consists of a 'volume of fluid' type method for the interface capturing and a force-balanced continuum surface force model for the surface tension on adaptive unstructured meshes. The numerical framework is validated against experimental measurements of a droplet impact problem and is then used to study the droplet deposition onto a flowing liquid film at atmospheric and high pressure conditions. Detailed complex interfacial structures during droplet impact are captured during the simulation, which agree with the experimental observations, demonstrating the capability of the present method. It is found that the effect of the ambient pressure on the fluid properties and interfacial tension plays an important role in the droplet deposition process and the associated interfacial phenomena.