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Published on: February 3, 2014
Dynamical evolution of volume fractions in multipressure multiphase flow models
1Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA. chc@lanl.gov
Summary
Multiphase flow models need closure relations for phase pressures. This study introduces a framework using relative volumetric expansion rates to derive volume fraction evolution equations for pressure equilibrium.
Area of Science:
- Multiphase flow modeling
- Fluid dynamics
- Thermodynamics
Background:
- Single-pressure models are insufficient for multiphase flow.
- Multiphressure models require closure relations for phase pressures.
- Volume fraction evolution equations are commonly used closure relations.
Purpose of the Study:
- Develop a theoretical framework for constructing volume fraction evolution equations.
- Model the dynamic relaxation of volume fractions towards pressure equilibrium.
- Investigate the behavior of compressible multiphase mixtures.
Main Methods:
- Formulating submodels for relative volumetric expansion rates (DeltaE_i).
- Defining DeltaE_i based on pressure differences and characteristic sound wave transit times.
- Developing a provisional model for DeltaE_i.
Main Results:
- The proposed framework rigorously constructs volume fraction evolution equations.
- The provisional model demonstrates monotonic relaxation to pressure equilibrium.
- Instantaneous pressure equilibrium is achieved in the incompressible limit.
Conclusions:
- The theoretical framework provides a robust method for multiphase flow modeling.
- The relative volumetric expansion rate concept offers a new approach to closure relations.
- The model's monotonic convergence simplifies pressure equilibrium analysis.
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