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Reference Number EP/H01070X/1
Title Novel hybrid LES-RANS schemes for simulating physically and geometrically complex turbulent flows
Status Completed
Energy Categories ENERGY EFFICIENCY(Transport) 20%;
FOSSIL FUELS: OIL, GAS and COAL(Oil and Gas, Oil and gas combustion) 10%;
OTHER POWER and STORAGE TECHNOLOGIES(Electric power conversion) 20%;
NOT ENERGY RELATED 50%;
Research Types Basic and strategic applied research 100%
Science and Technology Fields ENGINEERING AND TECHNOLOGY (Mechanical, Aeronautical and Manufacturing Engineering) 100%
UKERC Cross Cutting Characterisation Not Cross-cutting 100%
Principal Investigator Professor M Leschziner
No email address given
Aeronautics
Imperial College London
Award Type Standard
Funding Source EPSRC
Start Date 15 April 2010
End Date 14 October 2013
Duration 42 months
Total Grant Value £304,906
Industrial Sectors Aerospace; Defence and Marine
Region London
Programme NC : Engineering
 
Investigators Principal Investigator Professor M Leschziner , Aeronautics, Imperial College London (100.000%)
  Industrial Collaborator Project Contact , EDF Energy (0.000%)
Web Site
Objectives Linked to grant EP/H010998/1
Abstract Large Eddy Simulation (LES) is gradually replacing traditional Reynolds-averaged-Navier-Stokes (RANS) modelling as the method of choice for predicting complex turbulent flows in research as well as industrial practice. This is especially so when unsteady phenomena are to be resolved (vibrations, acoustics, thermal striping, pressure peaks). However, the exploitation of LES for predicting practical wall-confined flows, particularly those involving separation from curved surfaces, is seriouslyinhibited by practically untenable resource requirements at high Reynolds numbers. Hybrid LES-RANS schemes, employing some form of RANS-like solution in the near-wall region, are generally regarded as a compromise strategy circumventing the resource obstacle. Existing schemes are based on the use ofRANS models that operate in unsteady mode, as they are subjected to high amplitude, high-frequency fluctuations imposed on the layer by the outer LES solution. These models thus operate far outside their intended range of applicability. Moreover, in most approaches, the small-scale motions not resolved explicitly by the LES are represented by an ill-defined blend of subgrid-scale and RANS turbulence models - i.e. there is no clear dividing line between the LES and RANS components. Not surprisingly, such models display a whole range of disconcerting defects.This submission proposes a collaboration between two groups who have been at the forefront of developing RANS-LES schemes in the UK. Indeed, the two groups are the only UK academic partners who have participated in the four-year EU FP6 project DESider, specifically devoted to RANS-LES modelling for industrial applications, and in the follow-up 22-partner FP7 project ATAAC (Advanced Turbulence Simulation for Aerodynamic Application Challenges). Electricite de France (EDF) will support the programme to the level of one man-year of PDRA.The proposed project aims specifically at LES-RANS hybrids that distinguish carefully betweenthe LES and RANS elements, each applied subject to appropriate, well-established constrains and coupled rationally. The project involves two major strands:(i) the development of a novel zonal (two-layer) scheme, which entails the solution of steady, parabolized RANS equations, subject to on-the-fly time-averaged constraints derived from the LES solution, and the use of an anisotropy-resolving turbulence model over a thin near-wall layer superimposed onto the LES domain;(ii) the integration and validation of (i), as well as an extended version of a newly-developed RANS-LES hybrid (Uribe et al (2007)), which shares some basic concepts with proposed model under (i), into a state-of-the-art numerical framework (Saturne), which is promoted by EPSRC's CCP12 as a general prediction tool for computing turbulent flows in very complex geometries on HPCx and HECTOR. A key characteristic of Uribe et al's model is that it respects the need to separate the RANS-derived Reynolds stresses from the inherently unsteady LES, and to desensitize the resolved perturbations and the subgrids-scale stresses from the RANS model. To that extent, the model is based on the same philosophy underpinning the zonal scheme to be developed, although the two models differ radically in respect of their design
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Final Report (none)
Added to Database 10/09/09