Abstract:a b s t r a c tFlows in which shock waves and turbulence are present and interact dynamically occur in a wide range of applications, including inertial confinement fusion, supernovae explosion, and scramjet propulsion. Accurate simulations of such problems are challenging because of the contradictory requirements of numerical methods used to simulate turbulence, which must minimize any numerical dissipation that would otherwise overwhelm the small scales, and shock-capturing schemes, which introduce numerical … Show more
“…Similar conclusions were reached in a comprehensive study by Johnsen et al 13 The recent review by Pirozzoli 14 summarizes much of the work to date.…”
supporting
confidence: 63%
“…(9)- (13). The divergence form was tested in the course of this study to confirm the well-known instability characteristics of the method.…”
The last two decades have witnessed tremendous growth in computational power, the development of computational fluid dynamics (CFD) codes which scale well over thousands of processors, and the refinement of unstructured grid-generation tools which facilitate rapid surface and volume gridding of complex geometries. Thus, engineering calculations of 10 7 -10 8 finite-volume cells have become routine for some types of problems. Although the Reynolds Averaged Navier Stokes (RANS) approach to modeling turbulence is still in extensive and wide use, increasingly large-eddy simulation (LES) and hybrid RANS-LES approaches are being applied to resolve the largest scales of turbulence in many engineering problems. However, it has also become evident that LES places different requirements on the numerical approaches for both the spatial and temporal discretization of the Navier Stokes equations than does RANS. In particular, LES requires high time accuracy and minimal intrinsic numerical dispersion and dissipation over a wide spectral range. In this paper, the performance of both central-difference and upwind-biased spatial discretizations is examined for a one-dimensional acoustic standing wave problem, the Taylor-Green vortex problem, and the turbulent channel flow problem.
“…Similar conclusions were reached in a comprehensive study by Johnsen et al 13 The recent review by Pirozzoli 14 summarizes much of the work to date.…”
supporting
confidence: 63%
“…(9)- (13). The divergence form was tested in the course of this study to confirm the well-known instability characteristics of the method.…”
The last two decades have witnessed tremendous growth in computational power, the development of computational fluid dynamics (CFD) codes which scale well over thousands of processors, and the refinement of unstructured grid-generation tools which facilitate rapid surface and volume gridding of complex geometries. Thus, engineering calculations of 10 7 -10 8 finite-volume cells have become routine for some types of problems. Although the Reynolds Averaged Navier Stokes (RANS) approach to modeling turbulence is still in extensive and wide use, increasingly large-eddy simulation (LES) and hybrid RANS-LES approaches are being applied to resolve the largest scales of turbulence in many engineering problems. However, it has also become evident that LES places different requirements on the numerical approaches for both the spatial and temporal discretization of the Navier Stokes equations than does RANS. In particular, LES requires high time accuracy and minimal intrinsic numerical dispersion and dissipation over a wide spectral range. In this paper, the performance of both central-difference and upwind-biased spatial discretizations is examined for a one-dimensional acoustic standing wave problem, the Taylor-Green vortex problem, and the turbulent channel flow problem.
“…It is one of the simplest environments to study the breakdown process of large-scale vortices into successively smaller ones, and the resulting homogeneous isotropic turbulence [24,25]. In the past decade, the Taylor-Green vortex has become a popular reference case, used in a series of studies on LES methods, e.g., by Fauconnier et al [25], Drikakis et al [26], Chandy and Frankel [27], Johnsen et al [28], Adams [29], and Gassner and Beck [30]. We select the Reynolds number Re = 3000, which is large enough so that natural transition into small-scale homogeneous isotropic decaying turbulence occurs.…”
“…Thus, turbulence simulations re-quire the minimization of numerical dissipation for small scale representation, while the shocks require increased local dissipation to regularize the algorithm [4]. Explicit subgrid models also need to account for the presence of the shock.…”
Abstract. The statistics of the subgrid scales (SGS) are studied in the context of Large Eddy Simulations (LES) of turbulence after the interaction with a nominally normal shock wave. In general, in practical applications, the shock wave width is much smaller than the turbulence scales and the upstream turbulent Mach number is modest. In this case, recent high resolution shock-resolved Direct Numerical Simulations (DNS) (Ryu and Livescu, J. Fluid Mech., 756, R1, 2014) show that the interaction can be described by the Linear Interaction Approximation (LIA). By using LIA to alleviate the need to resolve the shock wave, DNS post-shock data can be generated at much higher Reynolds numbers than previously possible. Here, such results with Taylor Reynolds number ≈ 180 are used for an analysis of the SGS backscatter properties. In particular, it is shown that the interaction with the shock wave decreases the asymmetry of the SGS dissipation Probability Density Function (PDF) as the shock Mach number increases, with a significant enhancement in size of the regions and magnitude of backscatter.
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