Modeling of the scattering response of particulate obscurant clouds

Obscurants are often clouds of dispersed particulate materials whose purpose is to mask a given object. The objective of this paper is to develop a simple discrete-ray/discrete-particle model in order to enable rapid assessment of the response of an obscurant cloud to an incoming high-frequency beam. The beam is decomposed into a set of discrete rays and the obscurant is represented by a discrete set of scattering particles. Ray-tracking is used to calculate the transient propagation of the rays and the absorption of energy by the particles. Examples are given, comprised of concentrated incident beams, their propagation into the obscurant cloud, and the subsequent reflection and transmitted aggregate response. Basic system trends are computed, varying the randomly dispersed particle shapes from spherical to oblate objects, which correlate the total amount of volume and surface area material available to interact with the beam and the overall scattering response. This allows further correlation of the obscurant cloud performance to the weight of the material, which is important for portable containers of dispersible obscurants, such as smoke grenades. Specifically, the model allows for rapid quantification of the modest reduction of scattering efficiency of flakes, relative to spheres, but which have significantly less weight than spheres. Thus, there is a trade-off between the weight of the dispersed system and its scattering efficiency.