Partially-averaged Navier–Stokes simulations of two bluff body flows

Krajnović, Siniša; Minelli, Guglielmo; Basara, Branislav

doi:10.1016/j.amc.2015.03.136

Cited by 20 publications

(13 citation statements)

References 30 publications

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“…When the GTS model was placed above the ground at G ¼ 1:1H, flow state II was observed when PANS -CDS was used; while PANS -ASB showed a pair of symmetrical vortices in both the lateral and vertical midplanes at this gap height, and thus fails to accurately predict the asymmetrical flow topology observed behind the GTS. Very low values of the dynamic parameter -f k are observed for both these cases, resulting in insufficient turbulence modelling as the unresolved kinetic energy is very low (Krajnovi c et al (2016)). In such cases, the influence of the numerical scheme plays a larger role (see Pereira et al (2018b)), and CDS accurately predicts the flow asymmetry in the vertical midplane.…”

Section: Discussionmentioning

confidence: 99%

Investigation of the near-wake flow topology of a simplified heavy vehicle using PANS simulations

Rao

Minelli

Zhang

et al. 2018

Journal of Wind Engineering and Industrial Aerodynamics

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The near-wake flow topology of a ground transportation system (GTS) is investigated using partially-averaged Navier-Stokes (PANS) simulations at Re ¼ 2:7 Â 10 4. Recent numerical investigations for the GTS model using large eddy simulations (LES) showed an anti-symmetric flow topology (flow state II) in the vertical midplane compared to that observed in previous experimental studies (flow state I). The geometrical configuration of the GTS permits bi-stable behaviour, and the realisation of each of the two flow states, which are characterised by an asymmetrical flow topology, is achieved by varying the differencing scheme for the convective flux in the PANS simulations; AVL SMART schemes predict flow state I, while central differencing scheme (CDS) predicts flow state II. When the GTS model was placed away from the ground plane, the AVL SMART scheme fails to predict the flow asymmetry resulting in a pair of symmetrical vortices in the vertical midplane, while flow state II topology is observed when CDS is used. The switch from flow state I (II) to flow state II (I) is achieved by changing the numerical scheme from AVL SMART (CDS) to CDS (AVL SMART), with an intermediate transient-symmetric (TS) state being observed during the switching process. The numerical scheme in the PANS simulations thus plays a critical role in determining the initial flow topology in the near wake of the GTS.

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Section: Discussionmentioning

confidence: 99%

Investigation of the near-wake flow topology of a simplified heavy vehicle using PANS simulations

Rao

Minelli

Zhang

et al. 2018

Journal of Wind Engineering and Industrial Aerodynamics

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“…The diffusive terms containing viscous and sub-grid terms are approximated by a central differencing interpolation of second-order accuracy. According to the previous study on the influence of the numerical scheme in PANS (Krajnović et al, 2016), and the usage in the prediction of flow past Ahmed bodies in a squareback configuration (Mirzaei et al, 2015), a second-order AVL SMART Relaxed scheme (AVL, 2014; Pržulj and Basara, 2001) was used for convective terms in PANS simulations. However, as the choice of numerical requirements plays an important role in the simulations (Pereira et al, 2015(Pereira et al, , 2017Krajnović et al, 2018), to evaluate the numerical errors of the simulations, a medium grid PANS simulation was performed using the same scheme in LES for the convective terms -central differencing scheme (CDS) as compared to AVL SMART Relaxed scheme (Appendix A).…”

Section: Partially-averaged Navier-stokesmentioning

confidence: 99%

“…This allows for flexibility in the method as RANS modelling can provide sufficient levels of Reynolds stresses when the grid is not adequate to resolve the turbulence. PANS has previously been used for several different bluff body flows, such as flows around cubes (Krajnović et al, 2012a(Krajnović et al, , 2016, cylinders (Lakshmipathy and Girimaji, 2010;Jeong and Girimaji, 2010;Luo et al, 2014;Pereira et al, 2018) and simplified vehicles (Mirzaei et al, 2015;Han et al, 2013;Rao et al, 2018;Krajnović et al, 2012b). Most of these studies show that flow predictions of PANS are in good agreement with the experimental data, and often better than LES, when the mesh is relatively coarse.…”

Section: Introductionmentioning

confidence: 99%

Comparison of PANS and LES of the flow past a generic ship

et al. 2018

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The prediction of flow past a generic ship has been performed using partially-averaged Navier-Stokes (PANS) turbulence model. The Reynolds number based on the width of the ship is × 8 10 4. A detailed comparison with resolved large-eddy simulation (LES) solution and available experimental data is made for a better understanding of the capability of PANS in predicting the turbulent flow in the wake. The results show that PANS produces similar trends to those predicted by LES. However, a coarse grid resolution will lead PANS to act as unsteady Reynolds-averaged Navier-Stokes (URANS). Although the geometry is symmetric for the incoming flow at a zero yaw angle, bi-stable behaviour is observed in the wake, contributing to an asymmetric flow distribution on the heli-deck.

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“…The PANS model has been used for simulating complex flows encountered in engineering applications such as the turbulent flows past a square and circular cylinder [42, 149], the flow around a rudimentary landing gear [44], the flows over periodic hills both at the Reynolds number R e = 10595 and R e = 37000 [146], the flow around a simplified vehicle model [150, 151] as well bluff body flows [152]. These applications often emphasize the ability of the approach to simulate big unsteady eddying motions.…”

Section: Popular Hybrid Rans/les Methodsmentioning

confidence: 99%

The State of the Art of Hybrid RANS/LES Modeling for the Simulation of Turbulent Flows

Chaouat

2017

Flow Turbulence Combust

177

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This review presents the state of the art of hybrid RANS/LES modeling for the simulation of turbulent flows. After recalling the modeling used in RANS and LES methodologies, we propose in a first step a theoretical formalism developed in the spectral space that allows to unify the RANS and LES methods from a physical standpoint. In a second step, we discuss the principle of the hybrid RANS/LES methods capable of representing a RANS-type behavior in the vicinity of a solid boundary and an LES-type behavior far away from the wall boundary. Then, we analyze the principal hybrid RANS/LES methods usually used to perform numerical simulation of turbulent flows encountered in engineering applications. In particular, we investigate the very large eddy simulation (VLES), the detached eddy simulation (DES), the partially integrated transport modeling (PITM) method, the partially averaged Navier-Stokes (PANS) method, and the scale adaptive simulation (SAS) from a physical point of view. Finally, we establish the connection between these methods and more precisely, the link between PITM and PANS as well as DES and PITM showing that these methods that have been built by different ways, practical or theoretical manners have common points of comparison. It is the opinion of the author to consider that the most appropriate method for a particular application will depend on the expectations of the engineer and the computational resources the user is prepared to expend on the problem.

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Partially-averaged Navier–Stokes simulations of two bluff body flows

Cited by 20 publications

References 30 publications

Investigation of the near-wake flow topology of a simplified heavy vehicle using PANS simulations

Investigation of the near-wake flow topology of a simplified heavy vehicle using PANS simulations

Comparison of PANS and LES of the flow past a generic ship

The State of the Art of Hybrid RANS/LES Modeling for the Simulation of Turbulent Flows

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