WindWizard User’s Guide

摘要: WindWizard is an interface to a computational fluid dynamics model (CFD)(FLUENT®) to simulate the mechanical influence terrain has on air flow (Butler and others 2004). CFD technology was initially developed by the aerospace and automotive industries to simulate fluid flow around or through aircraft, automobiles, pipes, etc. WindWizard output is wind velocity and direction (20-foot) in raster and vector format (commonly 30-300 m resolution). Multiple runs of wind speed and direction can be simulated to create a “wind library” for use in prescribed fire planning, wildland fire use, wildfires, and reviews.Surface winds for an instant in time are calculated using terrain information obtained from a digital elevation model (DEM)(USGS 1990) and a user-defined upper-level wind speed and direction. This input speed differs from the 20-ft wind speed; usually, two to three times that of the observed 20-ft ridgetop wind to produce the desired results. Simulations assume a neutrally stable atmosphere and do not include buoyancy effects (diurnal and fire induced winds). WindWizard output is not a forecast, but a snapshot in time of what the local surface winds may be given the synoptic wind scenario (Butler and others 2006a).