This paper presents a numerical prediction method of an unsteady turbulent flow of air driven by fire source in a two- or three-dimensional compartment. In this case,the natural convection in a fire compartment is characterized by so strong gradient of temperature that the flow in the compartment should be regarded as a compressible one.

In the first part of this paper,the formulation of a turbulent gas flow on the time-smoothed physical variables with the concept of the eddy viscosity is discussed,and then a series of the governing equations are deduced.

In the main part,some practical approximation schemes on the differential equations are introduced from the view point of the numerical calculation,and these schemes are further represented by the finite difference approximations with a cell model for the spatial differencing. The validity of the schemes is discussed by applying them to a similar problem.

In the last part,the prediction method developed in the first and main parts of this paper is applied to the unsteady simulation of the natural convection due to a fire source in two- or three-dimensional compartment. Some features of two- or three-dimensional convection are described by refering the distributions of the physical properties in compartment which are obtained by the calculations.

* This report was reproduced from the manuscript prepared for the Second Joint Meeting,U.S. Japan Panel on Fire Research and Safety,UJNR,Tokyo,Octo. 19-22,1976. And,some part of this report overlaps with the content of the former report of the same auther (BRI Research Paper,No.66,June,1976).

* Research Member,Smoke Safety Engineering Section
Building Research Institute,Ministry of Construction
Japanese Government