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Large eddy simulation of flow over a wooded building complex

  • Rehm, R.G. (Building and Fire Research Laboratory, National Institute of Standards and Technology) ;
  • McGrattan, K.B. (Building and Fire Research Laboratory, National Institute of Standards and Technology) ;
  • Baum, H.R. (Building and Fire Research Laboratory, National Institute of Standards and Technology)
  • Published : 2002.04.25

Abstract

An efficient large eddy simulation algorithm is used to compute surface pressure distributions on an eleven story (target) building on the NIST campus. Local meteorology, neighboring buildings, topography and large vegetation (trees) all play an important part in determining the flows and therefore the pressures experienced by the target. The wind profile imposed at the upstream surface of the computational domain follows a power law with an exponent representing a suburban terrain. This profile accounts for the flow retardation due to friction from the surface of the earth, but does not include fluctuations that would naturally occur in this flow. The effect of neighboring buildings on the time dependent surface pressures experienced by the target is examined. Comparison of the pressure fluctuations on the single target building alone with those on the target building in situ show that, owing to vortices shed by the upstream buildings, fluctuations are larger when such buildings are present. Even when buildings are lateral to or behind the target, the pressure disturbances generate significantly different flows around this building. A simple grid-free mathematical model of a tree is presented in which the trunk and the branches are each represented by a collection of spherical particles strung together like beads on a string. The drag from the tree, determined as the sum of the drags of the component particles, produces an oscillatory, spreading wake of slower fluid, suggesting that the behavior of trees as wind breakers can be modeled usefully.

Keywords

References

  1. Baker, C.J. and H.J. Bell (1992), "The aerodynamics of urban trees", J. Wind Eng. Ind. Aerod., 41-44, 2655- 2666.
  2. Johnson, R.C., Ramey, G.E. and O'Hagan, D.S. (1981), "Wind induced forces on trees", Paper 81-WA/FE-7, Fluids Engineering Division of the American Society of Mechanical Engineers, Winter Annual Meeting, November 15-20, 1981, Washington, D.C.
  3. Lim, David, Private communication: Titan Corporation, Titan Research and Technology Division Internal Reports, "Validation of the NIST LES for Urban Flow Simulations", September 28, 1999 and "Evaluation of the LES Code for Urban Flow Simulations. Part II", March 3, 2000.
  4. McGrattan, K.B., H.R. Baum and R.G. Rehm, (1998), "Large eddy simulations of smoke movement", Fire Safety J., 30, 161-178. https://doi.org/10.1016/S0379-7112(97)00041-6
  5. McGrattan, K.B., H.R. Baum, R.G. Rehm, A. Hamins and G.P. Forney, "Fire dynamics simulator - technical reference manual", NISTIR 6467, National Institute of Standards and Technology, January 2000.
  6. Raupach, M.R. and A.S. Thom (1981), "Turbulence in and above plant canopies", Annual Reviews of Fluid Mech., 13, 97-129. https://doi.org/10.1146/annurev.fl.13.010181.000525
  7. Gross, Gunter, Numerical Simulations of Canopy Flows, Springer-Verlag, New York, 1993.
  8. Rehm, R.G., K.B. McGrattan, H.R. Baum and E. Simiu, "An efficient large eddy simulation algorithm for computational wind engineering: Application to surface pressure computations on a single building", NISTIR 6371, National Institute of Standards and Technology, August 1999.
  9. Roodbaraky, H.J., C.J. Baker, A.R. Dawson and C.J. Wright (1994), "Experimental observations of the aerodynamic characteristics of urban trees", J. Wind Eng. Ind. Aerod., 52, 171-184. https://doi.org/10.1016/0167-6105(94)90046-9
  10. Simiu, Emil and Robert H. Scanlan, Wind Effects on Structures, John Wiley \& Sons, Inc., Third Edition, 1996, 46.
  11. Swarztrauber, Paul and Roland Sweet, (1975), "Efficient fortran subprograms for the solution of elliptic partial differential equations", NCAR Techinical Note, NCAR-TN/IA-109, National Center for Atmospheric Research, Boulder, Colorado, July 1975.

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