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Efficient generation of inflow conditions for large-eddy simulation of street-scale flows

Record type: Article

Using a numerical weather forecasting code to provide the dynamic largescale inlet boundary conditions for the computation of small-scale urban canopy flows requires a continuous specification of appropriate inlet turbulence. For such computations to be practical, a very efficient method of generating such turbulence is needed. Correlation functions of typical turbulent shear flows have forms not too dissimilar to decaying exponentials. A digital-filter-based generation of turbulent inflow conditions exploiting this fact is presented as a suitable technique for large eddy simulations computation of spatially developing flows. The artificially generated turbulent inflows satisfy the prescribed integral length scales and Reynoldsstress-tensor. The method is much more efficient than, for example, Klein’s (J Comp Phys 186:652–665, 2003) or Kempf et al.’s (Flow Turbulence Combust 74:67–84, 2005) methods because at every time step only one set of two-dimensional (rather than three-dimensional) random data is filtered to generate a set of two-dimensional data with the appropriate spatial correlations. These data are correlated with the data from the previous time step by using an exponential function based on two weight factors. The method is validated by simulating plane channel flows with smooth walls and flows over arrays of staggered cubes (a generic urban-type flow). Mean velocities, the Reynolds-stress-tensor and spectra are all shown to be comparable with those obtained using classical inlet-outlet periodic boundary conditions. Confidence has been gained in using this method to couple weather scale flows and street scale computations.

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Citation

Xie, Zheng-Tong and Castro, Ian P. (2008) Efficient generation of inflow conditions for large-eddy simulation of street-scale flows Flow Turbulence and Combustion, 81, (3), 449 -470. (doi:10.1007/s10494-008-9151-5).

More information

Submitted date: 30 August 2007
Published date: 17 April 2008
Keywords: weather scale, urban cfd, coupling, bluff bodies, channel flow
Organisations: Aerodynamics & Flight Mechanics

Identifiers

Local EPrints ID: 52402
URI: http://eprints.soton.ac.uk/id/eprint/52402
ISSN: 1386-6184
PURE UUID: 2db3f200-f4ed-4ef0-9cbe-ffa3692ce8e4
ORCID for Zheng-Tong Xie: ORCID iD orcid.org/0000-0002-8119-7532

Catalogue record

Date deposited: 08 Jul 2008
Last modified: 17 Jul 2017 14:40

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