The University of Utah Large-Eddy Simulation Model

(under construction)

The University of Utah Large-Eddy Simulation Model (UU LES) has been developed over the course of several years by myself (Mike Zulauf).. The basics of the original model are described in the appendices of my PhD dissertation Modeling the Effects of Boundary Layer Circulations Generated by Cumulus Convection and Leads on Large-Scale Surface Fluxes.

Since that time, numerous capabilities, extensions, and improvements have been added to the model. Several of the more recent additions are described in these documents describing some of the numerical methods and algorithms, as well as handling of the LES thermodynamic and microphysical variables.

Very briefly, some of the current features of the model include:

• parallel and serial implementations built upon a common code base, parallelization in a SPMD framework built upon the MPI libraries
• mixed phase (liquid/ice) cloud particles
• Fu-Liou radiation parameterization
• full bulk microphysical parameterization
• quasi-compressible dynamics (reduced speed of sound), time-split for computational economy
• advanced scalar advection scheme, Modified UTOPIA with flux-corrected transport
• vertically stretched grid

The model has been used to simulate a large number of different types of atmospheric flows and cloud regimes. In addition, the LES has recently been coupled with a physically-based wildfire fire-spread model. Selected results from past simulations are shown separately.

Information on parallel performance and scaling is also available. Note, this is for a rather small problem, and thus scaling suffers when too many processors are used. Scaling is significantly better for larger problem sizes.