Three dimensional simulations of Richtmyer-Meshkov instabilities in gas-curtain shock-tube experiments
- Los Alamos National Laboratory
It is not feasible to compute high Reynolds-number (Re) turbulent flows by directly resolving all scales of motion and material interfaces; instead, macroscale portions of the unsteady turbulent motion are computed while the rest of the flow physics including molecular diffusion and other micro scale physics (e.g., combustion) remains unresolved. In large eddy simulation (LES), the large energy containing structures are resolved whereas the smaller, presumably more isotropic, structures are filtered out and their unresolved subgrid scale (SGS) effects are modeled. The construction of SGS models for LES is pragmatic and based primarily on empirical information. Adding to the physics based difficulties in developing and validating SGS models, truncation terms due to discretization are comparable to SGS models in typical LES strategies, and LES resolution requirements become prohibitively expensive for practical flows and regimes. Implicit LES (ILES) - and monotone integrated LES (MILES) introduced earlier, effectively address the seemingly insurmountable issues posed to LES by underresolution, by relying on the use of SGS modeling and filtering provided implicitly by physics capturing numerics. Extensive work has demonstrated that predictive unresolved simulations of turbulent velocity fields are possible using any of the class of nonoscillatory finite-volume (NFV) numerical algorithms. Popular NFV methods such as flux-corrected transport (FCT), the piecewise parabolic method (PPM), total variation diminishing (TVD), and hybrid algorithms are being used for ILES. In many applications of interest, turbulence is generated by shock waves via Richtmyer-Meshkov instabilities (RMI). The instability results in vorticity being introduced at material interfaces by the impulsive loading of the shock wave. A critical feature of this impulsive driving is that the turbulence decays as dissipation removes kinetic energy from the system. RMI add the complexity of shock waves and other compressible effects to the basic physics associated with mixing; compressibility further affects the basic nature of material mixing when mass density and material mixing fluctuation effects are not negligible. Because RMI are shock-driven, resolution requirements make direct numerical simulation impossible even on the largest supercomputers. State-of-the-art simulations of RMI instabilities use hybrid methods which require switching between the use of shock capturing schemes and conventional (explicit) LES depending on the local flow conditions. On the other hand. because ILES is based on (locally adaptive) NFV methods it is naturally capable of emulating shock physics. The unique combination of shock and turbulence emulation capabilities supports direct use of ILES as an effective simulation anzatz in RMI research. This possibility is explored in the current paper in the context of a prototypical case study for which the available laboratory data can be used to test and validate ILES modeling based on various NFV methods.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC52-06NA25396
- OSTI ID:
- 989837
- Report Number(s):
- LA-UR-09-03732; LA-UR-09-3732; TRN: US1007168
- Resource Relation:
- Conference: AIAA Aerospace Sciences Meeting ; January 4, 2010 ; Orlando, FL
- Country of Publication:
- United States
- Language:
- English
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