Effects of problem complexity reduction on parameter sensitivity and classification in charring ablator scenarios

Abstract

We investigate here effects of adaptations like dimension reduction, omission of parameter correlation, and grid refinement on parameter influence over material temperature response and total recession. The task is accomplished by applying Morris screening and method of Sobol' sensitivity studies applied to a range of 3-D, 1-D, and 1-D TC1-driver cases for the MSL entry through the Martian atmosphere, where the material response of the MSL heat shield is simulated with NASA's PATO toolbox. Results of the investigation show that lower-dimensional approaches can, in some cases, be utilized for initial parameter screening prior to execution of a fully-detailed simulation, but in general, obtained sensitivities differ. Moreover, coarse computational grids do not impose significantly distinct input-output mechanics and can be utilized for accurate screening and quantitative sensitivity analysis exercises even with non-negligible residual values. The investigation also discusses the implications of an unknown correlation structure on parameter sensitivities while finding little evidence of significant correlation effects on parameter classification given input uncertainty bounds defined in this work.