CPL - Chalmers Publication Library
| Utbildning | Forskning | Styrkeområden | Om Chalmers | In English In English Ej inloggad.

Zonal PANS: evaluation of different treatments of the RANS-LES interface

Lars Davidson (Institutionen för tillämpad mekanik, Strömningslära)
Journal of Turbulence (1468-5248). Vol. 17 (2016), 3, p. 274-307.
[Artikel, refereegranskad vetenskaplig]

The partially Reynolds-averaged Navier-Stokes (PANS) model can be used to simulate turbulent flows either as RANS, large eddy simulation (LES) or DNS. Its main parameter is f(k) whose physical meaning is the ratio of the modelled to the total turbulent kinetic energy. In RANS f(k) = 1, in DNS f(k) = 0 and in LES f(k) takes values between 0 and 1. Three different ways of prescribing f(k) are evaluated for decaying grid turbulence and fully developed channel flow: f(k) = 0.4, f(k) = k(tot)(3/2)/E and, from its definition, f(k) = k/k(tot) where k(tot) is the sum of the modelled, k, and resolved, k(res), turbulent kinetic energy. It is found that the f(k) = 0.4 gives the best results. InGirimaji and Wallin, a method was proposed to include the effect of the gradient of f(k). This approach is used at RANS- LES interface in the present study. Four different interface models are evaluated in fully developed channel flow and embedded LES of channel flow: in both cases, PANS is used as a zonal model with f(k) = 1 in the unsteady RANS (URANS) region and f(k) = 0.4 in the LES region. In fully developed channel flow, the RANS- LES interface is parallel to the wall (horizontal) and in embedded LES, it is parallel to the inlet (vertical). The importance of the location of the horizontal interface in fully developed channel flow is also investigated. It is found that the location - and the choice of the treatment at the interface - may be critical at low Reynolds number or if the interface is placed too close to the wall. The reason is that the modelled turbulent shear stress at the interface is large and hence the relative strength of the resolved turbulence is small. In RANS, the turbulent viscosity - and consequently also the modelled Reynolds shear stress- is only weakly dependent on Reynolds number. It is found in the present work that it also applies in the URANS region. E K, 1994, INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, V37, P139

Nyckelord: LES, PANS, 2G-RANS, zonal model, embedded LES, hybrid RANS-LES, RANS-LES interface condition



Denna post skapades 2016-03-23. Senast ändrad 2017-10-03.
CPL Pubid: 233633

 

Läs direkt!


Länk till annan sajt (kan kräva inloggning)


Institutioner (Chalmers)

Institutionen för tillämpad mekanik, Strömningslära (2005-2017)

Ämnesområden

Strömningsmekanik och akustik

Chalmers infrastruktur