Computer modeling of spacecraft parachutes, which are quite often used in clusters of two or three large parachutes, involves fluid–structure interaction (FSI) between the parachute canopy and the air, geometric complexities created by the construction of the parachute from “rings” and “sails” with hundreds of gaps and slits, and the contact between the parachutes. The Team for Advanced Flow Simulation and Modeling (T bigstar AFSM){({{rm T} bigstar {rm AFSM}})} has successfully addressed the computational challenges related to the FSI and geometric complexities, and recently started addressing the challenges related to the contact between the parachutes of a cluster. The core numerical technology is the stabilized space–time FSI technique developed and improved over the years by the T bigstar AFSM{{{rm T} bigstar {rm AFSM}}} . The special technique used in dealing with the geometric complexities is the Homogenized Modeling of Geometric Porosity, which was also developed and improved in recent years by the T bigstar AFSM{{{rm T} bigstar {rm AFSM}}} . In this paper we describe the technique developed by the T bigstar AFSM{{{rm T} bigstar {rm AFSM}}} for modeling, in the context of an FSI problem, the contact between two structural surfaces. We show how we use this technique in dealing with the contact between parachutes. We present the results obtained with the FSI computation of parachute clusters, the related dynamical analysis, and a special decomposition technique for parachute descent speed to make that analysis more informative. We also present a special technique for extracting from a parachute FSI computation model parameters, such as added mass, that can be used in fast, approximate engineering analysis models for parachute dynamics.
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