Computational Investigation of the Unsteady Flow Around a Parachute Model An Entry into the 2009 AIAA CFD Student Paper Competition

The unsteady aerodynamics of parachutes have been a challenge to study for years due to the coupling between the aerodynamic forces and system dynamics. This paper presents results from a Navier-Stokes flow solver simulating a steady inflow around a parachute model at a Reynolds number of 365,000. The parachute model, rigid and hemispherical in shape, is similar to that of a ribbon parachute with four ribbons or rings. Pressure results are compared to experimental data to judge accuracy of the simulations. Additional results include pressure and vorticity contours, as well as computational oil-flow visualizations and streamlines. These results illustrate the complex unsteady flow pattern in and around the ribbon parachute model. Nomenclature Cp pressure coefficient, = (pinside − poutside)/(0.5ρu2∞) d skirt diameter p static pressure Re Reynolds number, = (ρUd)/µ s surface shear stress u streamwise velocity v cross-stream vertical velocity w cross-stream in and out of page velocity Greek α angle of attack µ viscosity of water φ roll angle ρ fluid density ζ streamwise vorticity, = ∂v/∂x − ∂u/∂y Subscript ∞ freestream condition x, y, z streamwise, cross-stream vertical, and cross-stream in and out of page direction