Large-eddy simulation of turbulent flow above and within a forest
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A large-eddy simulation has been performed of an atmospheric surface layer in which the lower third of the domain is occupied by a drag layer and heat sources to represent a forest. Subgridscale processes are treated using second-order closure techniques. Lateral boundaries are periodic, while the upper boundary is a frictionless fixed lid. Mean vertical profiles of wind velocity derived from the output are realistic in their shape and response to forest density. Similarly, vertical profiles of Reynolds stress, turbulent kinetic energy and velocity skewness match observations, at least in a qualitative sense. The limited vertical extent of the domain and the artificial upper boundary, however, cause some departures from measured turbulence profiles in real forests. Instantaneous turbulent velocity and scalar fields are presented which show some of the features obtained by tower instrumentation in the field and in wind tunnels, such as the vertical coherence of vertical velocity and the slope of structures revealed by temperature patterns.
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- Cionco, R. M.: 1979, ‘A Summary of an Analysis of Canopy Flow Coupling for a Variety of Canopy Types’, pp. 105–106, preprint volume, 14th Conference of the American Meteorological Society on Agriculture and Forest Meteorology, Minneapolis, Minnesota, April 1979.Google Scholar
- Denmead, O. T. and Bradley, E. F.: 1985, ‘Flux-Gradient Relationships in a Forest Canopy’, in B. A. Hutchison and B. B. Hicks (eds.),The Forest-Atmosphere Interaction, D. Reidel, Dordrecht, pp. 421–442.Google Scholar
- Finnigan, J. J.: 1979, ‘Turbulence in Waving Wheat II. Structure of Momentum Transfer’,Boundary-Layer Meteorol. 16, 213–236.Google Scholar
- Nieuwstadt, F. T. M., Mason, P. J., Moeng, C.-H., and Schumann, U.: 1992, ‘Large-Eddy Simulation of the Convective Boundary Layer: A Comparison of Four Computer Codes’,Turbulent Shear Flows 8 (F. Durstet al., eds.), Springer-Verlag, Berlin, in press.Google Scholar
- Raupach, M. R., Antonia, R. A., and Rajagopalan, S.: 1991, ‘Rough-Wall Turbulent Boundary Layers’,Applied Mechanics Reviews 44, 1–25.Google Scholar
- Raupach, M. R., Finnigan, J. J., and Brunet, Y.: 1989, ‘Coherent Eddies in Vegetation Canopies’,Proc. Fourth Australasian Conf. on Heat and Mass Transfer, Christchurch, New Zealand, 9–12 May, pp. 75–90.Google Scholar
- Schmidt, H. and Schumann, U.: 1989, ‘Coherent Structure of the Convective Boundary Layer Derived from Large-Eddy Simulations’,J. Fluid Mech. 200, 511–562.Google Scholar
- Shaw, R. H. and Seginer, I.: 1985, ‘The Dissipation of Turbulence in Plant Canopies’, pp. 200–203, preprint volume, 7th Symposium of the American Meteorological Society on Turbulence and Diffusion, Boulder, Colorado, November 1985.Google Scholar
- Townsend, A. A.: 1976,The Structure of Turbulent Shear Flow, Cambridge University Press, Cambridge, 429 pp.Google Scholar