Wildland Urban Interface Fire Dynamics Simulator (WFDS)

Project Description

The Wildland-Urban Interface Fire Dynamics Simulator (WFDS) is an extension of NIST's structural Fire Dynamics Simulator (FDS) to fuels that include vegetation. WFDS uses computational fluid dynamics methods to solve the governing equations for buoyant flow, heat transfer, combustion, and the thermal degradation of vegetative fuels. The solution method makes use of large eddy simulation techniques to solve the gas-phase equations on computational grids that are too coarse to directly resolve the detailed physical phenomena.

This page contains links to the National Institute of Standards and Technology (NIST) wildland-urban interface fire computer models and example input files. Validation of these models is ongoing but far from complete. Please keep this in mind when using the WFDS for problems outside the current scope of validation. See download sections below for information on the current state of validation.

In general, please use the FDS discussion group and issue tracker when you have questions, and refer to WFDS. You may also email Ruddy Mell at wmell@comcast.net

New users, please send an e-mail to Ruddy Mell so that he can inform you when new versions, capabilities, and a user guide are available.

Purpose and Scope

The Wildland-Urban Fire Dynamics Simulator is intended to help understand the interactions between fire in the wildlands and how it behaves differently when encountering a developed area. The physics of this change in fire behavior is the focus of this project, and this understanding may lead to the ability to design communities better able to wisthstand an approaching wildfire.

Methods

Progress in this line of research is made by studying fire behavior an in the wildland-urban interface, and developing equations that can predict that behavior. Models are created by combining what we know about fire physics with new information learned when such fires enter communities.

Implementation

1. Fuel element model. This model is fully integrated into FDS (links to the executable are also given below). In this approach the vegetation occupies a specified volume  (e.g., trees crowns).  In general, this model is to be used when the grid resolution can span the vegetation with a number of grid cells. Realistic fire spread through grass, or other surface fuels, can be simulated if the computational grid is sufficiently fine.
2. Boundary fuel model. This model has been incorporated into FDS5 but is undergoing testing. It is limited to surface fuels (e.g., ground cover, grass). Links to the out-dated version, more fully tested version but based on FDS4, are below.

As mentioned above, the procedure for running WFDS is the same as for FDS (only some of the inputs are different as can be seen in the sample input files below). Consult the FDS User Manual and the discussion group if you are having trouble and Ruddy is not available.