Discretization errors in large eddy simulation: on the suitability of centered and upwind-biased compact difference schemes

2004 ◽  
Vol 198 (2) ◽  
pp. 580-616 ◽  
Author(s):  
Noma Park ◽  
Jung Yul Yoo ◽  
Haecheon Choi
Author(s):  
L. E. B. Sampaio ◽  
A. O. Nieckele

Schemes for the discretization of spatial derivatives commonly employed in the numerical solution of Partial Differential Equations present intrinsic errors that become more important as the wave number content of solution field approaches the Nyquist criteria based on the mesh spacing. In many situations, this can be overcome by simply refining the mesh, so that the wavelength of the structures becomes much larger than the mesh spacing, and the discretization errors become again negligible. However, in some other cases, like in Large-Eddy Simulations of highly turbulent flows, the cost per discretization element is so high that further mesh refinement is prohibitive. In this case, it is more appropriate to work towards understanding and improving the numerical schemes, so that the wider possible range of the spectrum is accurately resolved, and the fewest possible number of degrees of freedom is needed to provide a satisfactory solution. By analyzing the similarities between the problems faced by numerical schemes and the challenges of sub-grid modeling in Large-Eddy Simulations (LES), an alternative for the numerical simulation of turbulence in the context of Large-Eddy Simulation is developed, that accumulates two main functionalities: represent the interaction between unresolved and resolved scales, while keeping the discretization errors at acceptable levels. The proposed scheme is of advective nature and has been applied in several test cases, ranging from simple one-dimensional convection of a passive scalar, to more complex turbulent flows. As a result, a better understanding of the role of discretization errors in Large-Eddy Simulation was obtained.


Author(s):  
Shirdish Poondru ◽  
Urmila Ghia ◽  
Karman Ghia

Subsonic, transitional flow through a low-pressure turbine (LPT) cascade is investigated using high-order compact difference scheme in conjunction with large-eddy simulation (LES). Three-dimensional simulations are performed at chord inlet Reynolds numbers (Re) of 25,000 and 50,000. The inlet Mach number is approximately 0.06. An MPI-based higher-order accurate, Chimera version of the FDL3DI flow solver developed by the Air Force Research Laboratory at Wright Patterson Air Force base, is extended for the present turbomachinery application. The implicit solver is based on an approximate factored time-integration method of Beam and Warming. Fourth-order compact-difference formulations are used for discretizing spatial derivatives in conjunction with sixth-order non-dispersive filtering. Solutions are obtained both with and without a sub-grid scale (SGS) model. A dual topology, 16-block, structured grid generated using GridPro is utilized for all simulations. The flow features are examined, and the results for both LES approaches are compared to each other, and with experimental data.


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