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The activity at FOI was mainly focused around the implementation of a Reynolds stress transport model into our CFD code for unstructured grids. We showed that standard DRSMs may be solved down to the wall together with the standard equation without any near-wall corrections. Only minor recalibration was needed in order to fulfil the log law. We are working with an industrial CFD code so efforts have been made in making the implementation as efficient and robust as possible. 2D and 3D test cases have been computed and our results are in general close to other DRSM results. One interesting observation is that the results obtained by EARSMs are in general close to those of the corresponding full DRSMs.

The contribution of Imperial College London has been targeted, principally, towards advanced anisotropy-resolving turbulence closures and their application to a range of physically complex “generic” flows in which 2d and 3d separation from continuous surfaces is the main linking feature. The closures included various non-linear eddy-viscosity models and explicit algebraic Reynolds-stress models as well as two full Reynolds-stress-transport models. The range of flows investigated extended from 2d separation in an asymmetric diffuser to the highly complex 3d flows around a 3d hill and a generic car body. For all geometries but one — the NACA 0012 aerofoil at moderate incidence — representatives from all three anisotropy-resolving model categories were investigated. One major conclusion derived from the studies is that observations made in statistically 2d flows often do not translate to much more complex 3d flows that feature massive separation and strong vortical transverse motion. While anisotropy-resolving closures may give a superior representation of the response of the stress field to different types of strain, they cannot account (in common with all other RANS models) for the complex dynamics associated with large-scale unsteadiness, and it appears that this remains a major obstacle to a satisfactory predictive performance of these models in highly separated conditions. In contrast, attached and mildly separated flows benefit from the much stronger fundamental rigour offered by elaborate anisotropy-resolving closures, but here too, the predictive performance varies greatly, and much depends on the precise details of the closure and its calibration.

The objective of the present study is to provide advanced statistical turbulence modelling closures for aerodynamic flows around bodies at high Reynolds number. This study has been carried out by means of theoretical analysis based on the IMFT’s experimental data-base (see part 2 of the book). The two-equation modelling has been reconsidered in the context of the URANS/Organised Eddy Simulation, OES approach in respect of modifying the turbulence length scale involved in the eddy-diffusion coefficient. This has been done from second-order moment closures considerations in OES, from DNS and from the experimental sspectra for the turbulence fluctuating energy.

The main focus of NUMECA during the FLOMANIA project was on the robust implementation of several established turbulence models and their validation on a range of generic and industrial test cases. NUMECA contribution strongly took benefit from interactions with other partners, UMIST in particular. In addition, grid adaptation criteria were developed. A last aspect concerned the implementation of the Detached Eddy Simulation (DES) in one of its solvers. During the course of this project, both NUMECA structured and unstructured solvers were put to use.

Here we briefly review the two numerical methods used by DLR during the FLOMANIA project as well as some remarks on the turbulence models available in these codes including some remarks on the implementation of DES and RSM. Furthermore some additional results obtained with the latter models are presented which are not mentioned elsewhere in this book.

This chapter summarises the work performed by St.-Petersburg State Technical University as a major sub-contractor in FLOMANIA. Along with a support of Partners’ work on implementation of the Detached-Eddy Simulation methodology (DES) being the main responsibility of SPTU within FLOMANIA, this includes some own DES and RANS studies carried out on requests of the Project coordinator.

This chapter describes the method used by the Technical University of Berlin and it summarises the highlight results obtained with this method in the course of FLOMANIA. The main results are the successful implementation and calibration of DES for three different models and the improved representation of flow physics with these DES implementations.

The preferred models of the consortium (SSG, k-w, STT, SCW) have been implemented in a recent open source FV software and tested. Numerical behaviour of two popular versions of the V2F model have been compared and a new formulation proposed, that combines the accuracy of the original version and stability of the degraded “code friendly version”. In the DES framework, the need for reduction of the EVM coefficient has been related to the stress-strain missalignment in rapidly changing time dependent mode and a single transport equation for this coefficient proposed. On the wall function front, the AWF of Craft and Gerasimov entailing an analytical integration of terms over the first cell (body force in particular) proved challenging to implement on unstructured grids, but was achieved. Towards the end of the project, a promising mathematical framework (Robin type conditions) was proposed, based on domain decomposition and mixed Dirichlet and Neumann conditions.

Flows with massive separation are challenging for conventional URANS turbulence models. In this study the flow about a NACA0012 airfoil was computed over a range of angles of attack (α) varying from zero to ninety degrees for both URANS and DES models. The detailed analysis at α = 60 degrees is presented in this section. The DES methods are compared against their parent URANS models and it is seen that for this separated flow, DES methods outperform their URANS counterparts.

The main targets for ANSYS in FLOMANIA are turbulence model improvements and the validation of established turbulence models. These issues are:

All models developments and applications are carried out with the fluid mechanics software CFX-5 of ANSYS Inc. (CFX-5, 2004).