Abstract
Double-averaging methodology is commonly used for investigating spatially heterogeneous flows such as boundary layer flows over rough permeable walls, for example natural streams flowing over gravel beds. However, spatial averaging volume suitable for open channel flows over rough beds is very thin in the bed-normal direction, whereas for porous media flows within the bed, similar length in all three directions is more ideal. This scale mismatch can be addressed by allowing the averaging volume to vary in space, so that its size can be adjusted to the physical characteristics of particular flow regions. This paper revisits the double-averaged continuity and momentum equations for a spatially variable averaging volume derived by Pokrajac & de Lemos (2015). Compared to the conventional double-averaged continuity and Navier-Stokes equations, the new equations contain an additional term which accounts for the spatial variation of the averaging volume. The new averaging procedure is illustrated using an example from the literature, which involves a 3-dimensional Large Eddy Simulation (LES) of open channel flow over a porous bed consisting of 5 layers of uniform size spheres.
Original language | English |
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Title of host publication | River Flow 2020 - Proceedings of the 10th Conference on Fluvial Hydraulics |
Editors | Wim Uijttewaal, Mario J. Franca, Daniel Valero, Victor Chavarrias, Claudia Ylla Arbos, Ralph Schielen, Ralph Schielen, Alessandra Crosato |
Publisher | CRC Press/Balkema |
Pages | 13-21 |
Number of pages | 9 |
ISBN (Electronic) | 9780367627737 |
Publication status | Published - 2020 |
Event | 10th Conference on Fluvial Hydraulics, River Flow 2020 - Virtual, Online, Netherlands Duration: 7 Jul 2020 → 10 Jul 2020 |
Publication series
Name | River Flow 2020 - Proceedings of the 10th Conference on Fluvial Hydraulics |
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Conference
Conference | 10th Conference on Fluvial Hydraulics, River Flow 2020 |
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Country/Territory | Netherlands |
City | Virtual, Online |
Period | 7/07/20 → 10/07/20 |
Bibliographical note
Publisher Copyright:© 2020 Taylor & Francis Group, London
Keywords
- Double-averaging
- Fluid-Porous interface
- Large Eddy Simulation (LES)
- Variable averaging volume