- Author
- McGrattan, K. B. | Baum, H. R. | Rehm, R. G.
- Title
- Large Eddy Simulations of Smoke Plumes.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Book or Conf
- Scale Modeling 2nd International Symposium. Proceedings. University of Kentucky. June 23-27, 1997, Lexington, KY, 59-72 p., 1997
- Keywords
- scale models | smoke plumes | simulation | high temperature gases | smoke transport | enclosures | computational fluid dynamics | mathematical models | fire plumes | aircraft hangars | equations
- Identifiers
- isolated fire plume; mesoscale fire plumes
- Abstract
- This paper describes a methodology for simulating the transport of smoke and hot gases in enclosures and in the open. Using efficient computational fluid dynamics and high performance computers, a specialized form of the Navier-Stokes equations are solved numerically. The fire is described in a manner consistent with a mixture fraction based approach to combustion, but the combustion phenomena themselves are not simulated. The mixing and transport of smoke and hot gases is calculated directly from an approximate form of the Navier-Stokes equations. The computations are three-dimensional and time-dependent, and are limited only by the spatial resolution of the underlying grid. Due to the efficiency of the algorithm, calculations employing over a million computational cells are routinely performed on workstations. Convective motion is resolved down to scales one hundredth the size of the charac-teristic length of the enclosure. For residential rooms or hotel units, this corresponds to 3-5 centimeter resolution; for industrial applications, 10-20 centimeters. A similar numerical technique has even been applied to calculate the trajectories of the smoke plumes from very large, outdoor fires. Even though the computational domain may span tens of kilometers, resolution in the range of 5 to 10 meters may be achieved through a simple parabolization of the steady-state equations. A brief description of the underlying mathematical model and computational techniques is presented. These ideas are then illustrated by examples showing the structure of isolated fire plumes, smoke movement in enclosures, and dispersal over complex terrain.