Computational Modeling of Disk-Gap Band Parachute

Future robotic and human missions to Mars will require new entry, descent and landing approaches capable of delivering higher mass systems than those of previous missions. Numerical simulation requires accurate modeling of highly unsteady, turbulent flows and the coupling with the lightweight parachute structure. This class of problems is commonly referred to a "fluid-structure interactions" (FSI).

Numerical studies are being carried out to analyze the inflated geometry and stresses for a disk-gap band parachute similar to the parachutes used in previous NASA Mars missions. The modeling makes use of the Finite Element Method (FEM) to determine equilibrium conditions for the parachute membrane-cable structure under loads due to pressure, internal stress, gravitational, and damping.

Studies are being conducted to determine the affect that different element types have on the predicted inflated geometry of the parachute. The research should pinpoint numerical aspects that may have an affect on the simulation. A MATLAB program was written to generate three types of meshes for the parachute canopy that will be used in the analysis. These include a structured quadrilateral mesh, a structured triangular mesh, and a semi-structured triangular mesh. The semi-structured triangular mesh de-refines the mesh elements towards the parachute apex (i.e., top vent) so that the elements remain approximately the same size as they are close to the apex and also to the outside edges of the parachute disk. The unstructured mesh decreases computation time for the numerical simulation and can also improved the stability for the simulation.

- Laura Steen, senior physics major