An algorithm has been devised for predicting the behaviors of sparsely spatially distributed particles impinging on a solid surface in a rarefied atmosphere. Under the stated conditions, prior particle-transport models in which (1) dense distributions of particles are treated as continuum fluids; or (2) sparse distributions of particles are considered to be suspended in and to diffuse through fluid streams are not valid. In the present algorithm, individual particle/surface interactions are modeled. The algorithm uses a few key parameters that can be determined experimentally for the particles of interest in a given application: These parameters are the coefficient of restitution, coefficient of transfer of momentum, diffusivity, and sticking velocity. If many representative particles are tracked through modeling by use of this algorithm, a statistically likely distribution of particles can be obtained.

This work was done by David W. Hughes of Goddard Space Flight Center. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Information Sciences category. GSC-15364-1

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