高阶精度格式在火灾模拟中的应用

Higher-order numerical scheme for fire simulations

对流作用在火灾诱导的烟气运动中占主导地位。为了更好地研究火灾诱导的烟气运动,该文构造了一种新的4阶精度的有限差分格式,用以离散火灾烟气运动的控制方程——低M ach数可压缩N av ier-S tokes方程的对流项。将此格式加入到美国国家标准技术局开发的火灾模拟软件F ireD ynam ics S im u lator(FDS)中,对典型的油池火灾和单室火灾的问题进行了数值模拟。将速度和温度分布的计算结果与实验结果和二阶精度的FDS程序计算结果相比较,结果表明该文提出的格式在较少的网格下得到了比二阶精度格式更接近于实验值的结果。这说明在火灾模拟中,相对于二阶精度的格式来说,高精度格式是一种更好的选择。

In fire induced buoyancy driven flows, convection will dominate diffusion in most cases. This paper presents a fourth-order finite difference scheme for the convective terms of the governing equations for fire induced flows. In this scheme, all the derivatives in the momentum equations are computed directly without using additional interpolation procedures as in traditional numerical schemes for staggered grids. The numerical scheme has been integrated into the Fire Dynamics Simulator （FDS） code developed by the Building and Fire Research Laboratory at. the US National Institutes of Standards and Technology （NIST）. Predicted velocity and temperature distributions for a typical pool fire and a room fire more accurately agreed with experimental data than the standard second-order scheme.