Accession Number : ADA498265


Title :   Interface Conditions for Hybrid RANS/LES Simulations of Complex and Compressible Flows


Descriptive Note : Final rept. 15 Feb 2006-15 Feb 2009


Corporate Author : MARYLAND UNIV COLLEGE PARK DEPT OF MECHANICAL ENGINEERING


Personal Author(s) : Piomelli, Ugo ; Balaras, Elias


Full Text : http://www.dtic.mil/get-tr-doc/pdf?AD=ADA498265


Report Date : 06 MAR 2009


Pagination or Media Count : 31


Abstract : We have demonstrated the applicability of synthetic turbulence coupled with the controlled-forcing method to generate eddies at the interface between RANS and LES in hybrid calculations. We obtained shorter transition regions and improved model accuracy. Realistic turbulence can be generated within 5 boundary-layer thicknesses of the RANS/LES interface even in cases in which the data supplied by the RANS is inaccurate, or the assumptions on which the forcing is based are invalid. We applied this technique in a variety of turbulent flows with uniformly good results. A single-block hybrid calculation was performed in a geometry that, although simple, presented several difficulties. We demonstrated that unless turbulent eddies are artificially generated at the RANS/LES interface, very significant errors appear in the flow statistics even at low order (skin-friction coefficient, mean velocity profile). Establishing realistic turbulent eddies capable to transport momentum, energy and mass, appears to be a critical factor for the accurate prediction of shallow separation by hybrid RANS/LES methods.


Descriptors :   *EDDIES(FLUID MECHANICS) , *TURBULENT FLOW , *TURBULENCE , *COMPRESSIBLE FLOW , INTERFACES , STATISTICS , BOUNDARY LAYER , COEFFICIENTS , SEPARATION , MEAN , NAVIER STOKES EQUATIONS , REYNOLDS NUMBER , SKIN FRICTION , MOMENTUM , PREDICTIONS , COMPUTATIONS , SHALLOW DEPTH , VELOCITY , SIMULATION


Subject Categories : FLUID MECHANICS


Distribution Statement : APPROVED FOR PUBLIC RELEASE