Permeability Modeling of Mars Parachute Broadcloth Materials

The broadcloth material used in parachute manufacturing is generally a thin, woven, permeable textile. The relatively small length scales of the pores and gaps inside the fabric make it challenging to resolve these features in a full-scale parachute simulation. Simulations are performed using a 3D reconstruction the geometry of the material used in the Mars 2020 mission, and simulation results using the detailed reconstructed geometry are compared to the simplified model previously proposed in (Huang, D. Z.,Wong, M. L., Lele, S. K., and Farhat, C., “Homogenized Flux-Body Force Treatment of Compressible Viscous Porous Wall Boundary Conditions,” AIAA Journal, Vol. 59, No. 6, 2021, pp. 2045–2059). Furthermore, results from simulations under Earth ambient lab conditions are compared to experimental permeability test data to verify the choice of a simplified geometry required for some reduced-order models. A series of simulations under ASPIRE SR03 flight conditions are also performed to study the permeability of the fabric in a rarefied flow regime. The flow inside the material is shown to be similar to a developing pipe flow that does not reach a fully developed state. Significant slip velocity is observed inside the individual pores in the material, and the pressure drag is found to be the primary contributor to the overall material drag. The previous analytical pipe flow solution based on a simplified pore geometry solution predicts a higher total drag by only a small amount (∼ 0.8%) compared to the results presented in this work. Therefore, while flow through the parachute material at the micro-scale shows interesting physics, adding more complex assumptions to simplified models, such as a slip wall boundary condition and rarefied effects, likely increases the computational cost and complexity without significantly changing the predicted drag on the material.