Debris flows constitute a severe natural hazard in Alpine regions. Studies are performed to understand the event predictability and to identify early warning systems and procedures. These are based both on sensors deployed along the channels or on the amplitude of seismic and infrasound waves radiated by the flow and recorded far away. Despite being very promising, infrasound cannot be used to infer the source characteristics due to the lack of a physical model of the infrasound energy radiated by debris flows. Here the simulation of water flow along a simple channel is presented, experiencing the fall from a dam, performed within the open source simulation code OpenFOAM. The pressure perturbation within the atmosphere produced by the flow is extracted and the infrasound signature of the events as a function of the flow characteristics is defined. Numerical results suggest that infrasound is radiated immediately downstream of the dam with amplitude and period that scale with dam height and water level. Modeled infrasound waveform is interpreted as being produced mostly by waves at the water free surface developing downstream of the dam. Despite the effect of sediments is not considered in this first study and will be implemented in future investigations, numerical results obtained with this simple model are in general agreement with experimental results obtained from array analysis of infrasound data recorded at Illgraben, Switzerland. Results highlight how numerical modeling can provide critical information to define a source mechanism of infrasound energy radiation by debris-flow, that is required also to improve early warning systems.

碎石流在阿尔卑斯地区构成严重的自然灾害。进行研究以了解事件的可预测性并确定早期预警系统和程序。它们基于沿通道部署的传感器，或基于流辐射并在远处记录的地震波和次声波的振幅。尽管很有前景，但由于缺乏泥石流辐射的次声能量的物理模型，因此不能用次声来推断震源特征。此处介绍了沿简单通道的水流模拟，体验了从大坝坠落的过程，在开源模拟代码 OpenFOAM 中执行。提取由流动产生的大气中的压力扰动，并定义作为流动特性函数的事件的次声特征。数值结果表明，次声直接在大坝下游辐射，其振幅和周期随大坝高度和水位成比例。模拟的次声波形被解释为主要由大坝下游自由水面的波浪产生。尽管在第一项研究中没有考虑沉积物的影响，并将在未来的调查中实施，但使用这个简单模型获得的数值结果与从瑞士 Illgraben 记录的次声数据阵列分析获得的实验结果大体一致。结果强调了数值建模如何提供关键信息来定义泥石流次声能辐射的来源机制，这也是改进早期预警系统所必需的。