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| Titel |
An Evaluation of Recently Developed RANS-Based Turbulence Models for Flow Over a Two-Dimensional Block Subjected to Different Mesh Structures and Grid Resolutions |
| VerfasserIn |
Farshid Kardan, Wai-Chi Cheng, Olivier Baverel, Fernando Porté-Agel |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250134770
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| Publikation (Nr.) |
 EGU/EGU2016-15534.pdf |
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| Zusammenfassung |
| Understanding, analyzing and predicting meteorological phenomena related to
urban planning and built environment are becoming more essential than ever
to architectural and urban projects. Recently, various version of RANS
models have been established but more validation cases are required to
confirm their capability for wind flows. In the present study, the
performance of recently developed RANS models, including the \textit{RNG k-$\varepsilon $, SST BSL k-$\omega $} and \textit{SST \gamma-Re}$_{\theta $},
have been evaluated for the flow past a single block (which represent the
idealized architecture scale). For validation purposes, the velocity
streamlines and the vertical profiles of the mean velocities and variances
were compared with published LES and wind tunnel experiment results.
Furthermore, other additional CFD simulations were performed to analyze the
impact of regular/irregular mesh structures and grid resolutions based on
selected turbulence model in order to analyze the grid independency. Three
different grid resolutions \textit{(coarse, medium and fine)} of \textit{N_x $\times $ N_y $\times $N_z = 320 $ \times $ 80 $ \times $ 320, 160 $ \times $ 40 $ \times $160} and \textit{80 $ \times $ 20 $ \times $ 80} for the computational domain and\textit{ n_x $ \times $ n_z = 26 $ \times $ 32, 13 $ \times $ 16} and \textit{6 $ \times $ 8},
which correspond to number of grid points on the block edges, were chosen
and tested. It can be concluded that among all simulated RANS models, the
\textit{SST \gamma-Re}$_{\theta $} model performed best and agreed fairly well to the LES simulation
and experimental results. It can also be concluded that the \textit{SST \gamma-Re}$_{\theta $} model
provides a very satisfactory results in terms of grid dependency in the
\textit{fine} and \textit{medium} grid resolutions in both regular and irregular structure meshes. On
the other hand, despite a very good performance of the \textit{RNG k-$\varepsilon $} model in the \textit{fine}
resolution and in the regular structure grids, a disappointing performance
of this model in the \textit{coarse} and \textit{medium} grid resolutions indicates that the \textit{RNG k-$\varepsilon $} model is
highly dependent on grid structure and grid resolution. These quantitative
validations are essential to access the accuracy of RANS models for the
simulation of flow in urban environment. |
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