Interface Retaining Coarsening of Multiphase Flows
arXiv:2106.00789 · doi:10.1063/5.0058776
Abstract
Multiphase flows are characterized by sharp moving interfaces, separating different fluids or phases. In many cases the dynamics of the interface determines the behavior of the flow. In a coarse, or reduced order model, it may therefore be important to retain a sharp interface for the resolved scales. Here, a process to coarsen or filter fully resolved numerical solutions for incompressible multiphase flows while retaining a sharp interface is examined. The different phases are identified by an index function that takes different values in each phase and is coarsened by solving a constant coefficient diffusion equation, while tracking the interface contour. Small flows scales of one phase, left behind when the interface is moved, are embedded in the other phase by solving another diffusion equation with a modified diffusion coefficient that is zero at the interface location to prevent diffusion across the interface, plus a pressure like equation to enforce incompressibility of the coarse velocity field. Examples of different levels of coarsening are shown. A simulation of a coarse model, where small scales are treated as a homogeneous mixture, results in a solution that is similar to the filtered fully resolved field for the early time Rayleigh-Taylor instability.
References in corpus (7)
- Hidden Physics Models: Machine Learning of Nonlinear Partial Differential Equations
- Energy transfer from large to small scales in turbulence by multi-scale nonlinear strain and vorticity interactions
- Coarse-scale PDEs from fine-scale observations via machine learning
- On the role of vorticity stretching and strain self-amplification in the turbulence energy cascade
- A New Approach to Sub-grid Surface Tension for LES of Two-phase Flows
- A Brief Survey of Recent Edge-Preserving Smoothing Algorithms on Digital Images
- A physics-inspired alternative to spatial filtering for large-eddy simulations of turbulent flows