A Robust High-Order Framework for Compressible Multi-phase Multi-component Flows with Interface Regularization, Phase Change, and Spray Modeling
Speaker: Henry Collis, Pacific Fusion
Time:
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Abstract
In recent years, computational physics has expanded capabilities in multiple aspects, including modeling compressible flow, multi-phase interfaces, multi-component diffusion and mixing processes, turbulence, and combustion. Individually, these are all active areas of research which require large allocations of time and resources to make progress. An overarching goal is to create a computational framework which is robust and accurate when including the modeling capabilities for all of the aforementioned physics. In particular, the multi-physics nature of this work requires a consistent computational framework at all levels, from the model forms to numerical implementations.
First, a robust computational framework with the four-equation model is proposed to simulate compressible multi-phase multi-component flows. An ENO-type scheme is designed to be consistent with the thermodynamic equilibrium assumptions of the four-equation multi-phase model, naturally enforcing the interface equilibrium condition — preventing oscillations in pressure, velocity, and temperature around isothermal material interfaces. The proposed four-equation framework accomplishes this without requiring explicit equations for volume fraction or other redundant transport equations for variables including mixture equation of state parameters, as is commonly done for the five-equation model. Additionally, consistent mixing rules are applied to capture leakage-free intraphase non-dilute species diffusion for multi-phase multi-component systems and used to extend the conservative diffuse interface (CDI) model to enforce immiscibility conditions for multi-phase multi-component flows. For robust simulations involving strong shock and material interface interactions, a conservative positivity-preserving limiter is applied locally in space for minimal degradation of the baseline ENO-type scheme. We show that this consistent framework is equally applicable for regimes ranging from single-phase to multi-phase multi-component flows.
Second, the multi-physics modeling capabilities including subgrid models for spray, finite-rate phase change, and phase-constrained combustion are shown to obtain accurate predictions of complex multi-phase flows at a reasonable cost. These models are coupled to solve complex flows, including simulation of a finite-rate evaporation of a diesel spray, and both the injection and ignition stages of a cryogenic liquid rocket combustor.
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