A Diffuse Interface Model with Immiscibility Preservation

Area of Science:

• Computational fluid dynamics
• Multiphase flow simulation
• Interface capturing schemes

Background:

• Accurate simulation of compressible multiphase flows is crucial for many engineering applications.
• Existing interface capturing methods often struggle with computational efficiency and accuracy, particularly for complex interface dynamics.
• The diffuse interface approach offers a promising avenue for representing interfaces without explicit tracking.

Purpose of the Study:

• To present a novel, computationally efficient interface capturing scheme for compressible multiphase flows.
• To enhance existing diffuse interface formulations by enforcing a selected interface thickness.
• To ensure asymptotic compatibility with thermodynamic mixture laws and preserve equilibrium flow conditions.

Main Methods:

• A diffuse interface approach using field variables (interface functions) with augmented transport equations.
• Enforcement of a specific interface thickness to balance resolution and computational efficiency.
• Incorporation of first-order pressure and velocity non-equilibrium effects.

Main Results:

• Demonstrated improved convergence in one-dimensional configurations.
• Enabled fundamentally better simulations of bubble dynamics, including spherical and jetting collapse.
• Showcased preservation of bubble symmetry and accurate simulation of jetting phenomena, unlike previous methods.

Conclusions:

• The proposed diffuse interface scheme offers a significant advancement in simulating compressible multiphase flows.
• The method provides a computationally efficient yet accurate way to model interface dynamics.
• This approach overcomes limitations of existing methods, leading to qualitatively correct results for complex scenarios like bubble collapse.