Analysis of free-surface flows through energy considerations: Single-phase versus two-phase modeling

Area of Science:

• Fluid dynamics
• Computational physics
• Multiphase flow

Background:

• Energetic free-surface flows involve complex air-water interfaces with fragmentation and bubble formation.
• Numerical simulations are increasingly used, often employing single-phase approximations for computational efficiency.
• The impact of air on global energy dissipation in these flows remains unclear with simplified models.

Purpose of the Study:

• To investigate the validity of single-phase approximations in predicting global mechanical energy dissipation in energetic free-surface flows.
• To compare energy evolution predictions between single-phase and two-phase numerical models.
• To understand the role of air phase energy dissipation.

Main Methods:

• Numerical simulation of a selected energetic free-surface flow problem.
• Comparison of results obtained using both single-phase and two-phase computational fluid dynamics (CFD) models.
• Analysis of local flow evolution and global mechanical energy dissipation.

Main Results:

• Flow evolutions differ significantly between single-phase and two-phase models.
• Global mechanical energy dissipation evolution shows similar trends for both models.
• In the two-phase model, approximately half the energy is dissipated in the air phase, unlike the single-phase model where dissipation occurs mainly through cavity collapses.

Conclusions:

• Single-phase approximations may be sufficient for predicting global energy dissipation in certain energetic free-surface flows, despite local differences.
• The study highlights the importance of considering air phase energy dynamics.
• This finding offers potential for computational cost reduction in simulating such complex fluid phenomena.