Flow over periodic hills – Numerical and experimental study in a wide range of Reynolds numbers

Breuer, M.; Peller, Nikolaus; Rapp, Ch.; Manhart, Michael

doi:10.1016/j.compfluid.2008.05.002

Cited by 263 publications

(304 citation statements)

References 33 publications

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“…It clearly appears that the RANS model gives too long a recirculation region, with a reattachment point located at x/h = 5.3, to be compared with x/h = 4.7 for the reference fine LES [29]. The two hybrid RANS/LES methods, T-PITM and equivalent-DES, yield very close reattachment points, both at x/h = 4.5.…”

Section: Periodic Hill Flowmentioning

confidence: 99%

“…The validity of the equivalence criterion is now assessed in a massively separated flow, far from the equilibrium assumptions used in the theoretical derivation, the periodic hill flow at Re b = 10595 [29], for which PITM proved successful [36]. The size of the computational domain is 9h × 3.035h × 4.5h (h is henceforth the height of the hill).…”

Section: Periodic Hill Flowmentioning

confidence: 99%

“…In order to compare the influence of the particular form of the equivalence relation obtained under different assumptions, four different computations are performed using equivalent-DES, using the four length scale relations plotted in figure 2. (ii) With the purpose of validating the applicability of the equivalence criteria in a case that does not comply with the equilibrium hypothesis of the theoretical analysis, a flow over a periodic hill at bulk Reynolds number Re b = 10595 is computed [29].…”

Section: Computational Validationmentioning

confidence: 99%

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Toward an equivalence criterion for Hybrid RANS/LES methods

2015

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A criterion is established to assess the equivalence between hybrid RANS/LES methods, called H-equivalence, based on the modeled energy of the unresolved scales, which leads to similar low-order statistics of the resolved motion. Different equilibrium conditions are considered, and perturbation analyses about the equilibrium states are performed. The procedure is applied to demonstrate the equivalence between two particular hybrid methods, and leads to relationships between hybrid method parameters that control the partitioning of energy between the resolved and unresolved scales of motion. This equivalence is validated by numerical results obtained for the cases of plane and periodically constricted channel flows. This concept of H-equivalence makes it possible to view different hybrid methods as models for the same system of equations: as a consequence, detached-eddy simulation (DES), which is shown to be H-equivalent to the temporal partially integrated transport model (T-PITM) in inhomogeneous, stationary situations, can be interpreted as a model for the subfilter stress involved in the temporally filtered Navier-Stokes equations.

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Section: Periodic Hill Flowmentioning

confidence: 99%

Section: Periodic Hill Flowmentioning

confidence: 99%

Section: Computational Validationmentioning

confidence: 99%

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Toward an equivalence criterion for Hybrid RANS/LES methods

2015

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“…It is understood from Figure 4 that in comparison with the relatively flat surface of the sea, the complex land topography tends to enhance the turbulence in the coastal area, which in turn influences the momentum flux. It was also reported in previous studies of flows past hills, steps, and ribs that the turbulence mixing is enhanced due to the complex bottom geometry [31][32][33][34][35][36]. Figure 5 compares the LES and COAMPS results of the turbulence momentum flux ρu w against the measurement data.…”

Section: Resultsmentioning

confidence: 87%

Numerical Study on the Effect of Air–Sea–Land Interaction on the Atmospheric Boundary Layer in Coastal Area

Yang

Calderer

et al. 2018

Atmosphere

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Abstract:We have performed large-eddy simulations (LES) to study the effect of complex land topography on the atmospheric boundary layer (ABL) in coastal areas. The areas under investigation are located at three beaches in Monterey Bay, CA, USA. The sharp-interface immersed boundary method is employed to resolve the land topography down to grid scale. We have considered real-time and what-if cases. In the real-time cases, measurement data and realistic land topographies are directly incorporated. In the what-if cases, the effects of different scenarios of wind speed, wind direction, and terrain pattern on the momentum flux at the beach are studied. The LES results are compared with simulations using the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS) and field measurement data. We find that the land topography imposes a critical influence on the ABL in the coastal area. The momentum fluxes obtained from our LES agree with measurement data. Our results indicate the importance of capturing the effects of land topographies in simulations.

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“…These are the resolution of the near-wall region and of the inner domain. Both criteria were seriously taken into account during the grid generation, see [3]. For the lower-Re cases considered, the grid was not modified.…”

Section: Numerical Setupmentioning

confidence: 99%