Building scale simulations in support of field experiments around Salt Lake City

Numerical modeling of the air motions around multiple buildings such as in urban street canyons has much promise for improving what is known about their effects on surrounding winds. This talk presents simulations that were done to support two observational programs involving the Salt Lake City basin. The Chemical/Biological Non-proliferation Program (CBNP) is concerned with the effects of buildings on influencing dispersion patterns in urban environments. One aspect of the Vertical Transport and Mixing Program (VTMX) investigates mixing in the stable boundary layer and how it is influenced by the channeling caused by drainage flows or by obstacles such as building complexes. Both programs are multiscale in scope and are interested in processes that range from the scale of drainage flows from the nearby mountains to that of very small boundary layer motions whose scale is reduced due to the strong stratification in the nocturnal stable boundary layer.

Attached is a picture of a dispersion pattern of a tracer release immediately behind the Salt Lake City Delta Center. This pattern was generated by the massively parallel, LLNL building model FEM3MP and is an example of several of the features that will be discussed in this talk. We see that the dispersion of the tracer is blocked by the Delta Center at the upper left and is channeled by two buildings on the lower right. We will present results from this model which show how these effects are influenced by stratification, details of the buildings, the resolution of the mesh and different boundary conditions.

This work was performed under the auspices of the U. S. Department of Energy by the University of California, Lawrence Livermore National Laboratory, under contract No. W-7405-ENG-48.