For more information:
tezduyar@gmail.com

Orion Spacecraft Parachutes
It is expected that NASA will be using a cluster of three ringsail parachutes during the terminal descent of the Orion spacecraft. These parachutes, referred to as the "mains", are being designed to support a weight of approximately 15,000 lbs at a steady descent speed of approximately 25 ft/s. Each parachute has 80 gores and a nominal diameter of about 120 ft. It has 4 "rings" and 9 "sails" (see [8, 9] for the terminology). To better understand the performance of the mains, we are modeling a single main parachute, carrying one third of the total weight of the space vehicle. We simulate the offloading, which involves dropping the heat shield prior to landing, and the drifting under the influence of a side wind at 12.5 ft/s.
The numerical methods used in these computations were introduced and implemented on parallel computing platforms by the T*AFSM. The set of numerical methods introduced by the T*AFSM over the years and used in this computation includes the DSD/SST formulation [14], the quasidirect FSI method [5, 6], the stabilized spacetime FSI (SSTFSI) technique [7], and a number of special FSI techniques [79]. Among the special FSI techniques used in the computation are the FSI Geometric Smoothing Technique (FSIGST) and the Homogenized Modeling of Geometric Porosity (HMGP) (see [8, 9]). The computations were carried out on the ADA system at Rice University. For more details on these computations, see [8, 9].

Fig. 1. Orion spacecraft (http://www.nasa.gov/mission_pages/constellation/multimedia/orion_contract_images.html). 

Fig. 2. Orion spacecraft main parachute. Reefed (left) and full (right) configurations (http://www.nasa.gov/mission_pages/constellation/multimedia/parachute_tests.html). 




Fig. 3. Parachute shape and flow field before and 6 s after the heat shield is dropped. For details, see [8, 9]. 

Fig. 4. Flow past the drifting parachute (side wind = 12.5 ft/s). For details, see [8, 9]. 

Fig. 5. Horizontal velocity for the drifting parachute (side wind = 12.5 ft/s). For details, see [8, 9]. 
References
1. T.E. Tezduyar, "Stabilized Finite Element Formulations for Incompressible Flow Computations", Advances in Applied Mechanics, 28 (1992) 144, doi: 10.1016/S00652156(08)701534.
2. T.E. Tezduyar, M. Behr and J. Liou, "A New Strategy for Finite Element Computations Involving Moving Boundaries and Interfaces  The DeformingSpatialDomain/SpaceTime Procedure: I. The Concept and the Preliminary Numerical Tests", Computer Methods in Applied Mechanics and Engineering, 94 (1992) 339351, doi: 10.1016/00457825(92)90059S.
3. T.E. Tezduyar, M. Behr, S. Mittal and J. Liou, "A New Strategy for Finite Element Computations Involving Moving Boundaries and Interfaces  The DeformingSpatialDomain/SpaceTime Procedure: II. Computation of Freesurface Flows, Twoliquid Flows, and Flows with Drifting Cylinders", Computer Methods in Applied Mechanics and Engineering, 94 (1992) 353371, doi: 10.1016/00457825(92)90060W.
4. T.E. Tezduyar, "Computation of Moving Boundaries and Interfaces and Stabilization Parameters", International Journal for Numerical Methods in Fluids, 43 (2003) 555575, doi: 10.1002/fld.505.
5. T.E. Tezduyar, S. Sathe, R. Keedy and K. Stein, "SpaceTime Techniques for Finite Element Computation of Flows with Moving Boundaries and Interfaces", Proceedings of the III International Congress on Numerical Methods in Engineering and Applied Sciences, Monterrey, Mexico, CDROM (2004).
6. T.E. Tezduyar, S. Sathe, R. Keedy and K. Stein, "SpaceTime Finite Element Techniques for Computation of FluidStructure Interactions", Computer Methods in Applied Mechanics and Engineering, 195 (2006) 20022027, doi: 10.1016/j.cma.2004.09.014.
7. T.E. Tezduyar and S. Sathe, "Modeling of FluidStructure Interactions with the SpaceTime Finite Elements: Solution Techniques", International Journal for Numerical Methods in Fluids, 54 (2007) 855900, doi: 10.1002/fld.1430.
8. T.E. Tezduyar, S. Sathe, J. Pausewang, M. Schwaab, J. Christopher and J. Crabtree, "Interface Projection Techniques for FluidStructure Interaction Modeling with MovingMesh Methods", Computational Mechanics, 43 (2008) 3949, doi: 10.1007/s0046600802617.
9. T.E. Tezduyar, S. Sathe, M. Schwaab, J. Pausewang, J. Christopher and J. Crabtree, "FluidStructure Interaction Modeling of Ringsail Parachutes", Computational Mechanics, 43 (2008) 133142, doi: 10.1007/s0046600802608.
