窄带水平集法下林火蔓延仿真研究

Numerical simulation on wildland fire spread with narrow-band level set method

火焰锋面的追踪是建立林火蔓延模型及预测锋面位置的关键环节。基于水平集法追踪锋面具有求解灵活稳定、易于处理锋面拓扑结构变化的特点。针对传统水平集法重新初始化过程复杂、计算量较大的问题,根据距离函数定义,提出通过形态学膨胀的方法以锋面点为圆心向外膨胀,获得锋面附近窄带内每个点距离锋面的最近距离,重建窄带内的水平集函数,物理意义明确,有效减小了计算量,在此基础上基于林火速度场经验模型模拟了单火源及双火源的锋面蔓延情况。结果表明,该方法能够有效模拟坡度、风速等因素对火焰锋面的影响,为其在林火蔓延模型中的应用提供了基础。

Fire front tracking is an important step for modeling wildland fire spread and predicting the position of fire front. Level set method is known for its versatile advantage of handling topological change of front. In this study, we proposed to reconstruct the narrow band near fire front using image inflation based on the definition of sign function to simplify the complicated calculation in classic level set method, which has definite physical meaning. Single-point source and two-point source are simulated. Results show that the method here can effectively simulate the effects of slope and wind speed, which provides a solid foundation for its further use in practical fire spread model.