Assessment of the Smoothed Particle Hydrodynamics formulations available in LS-DYNA for multiple-stage bird ingestion applications

Smoothed Particle Hydrodynamics (SPH) is the standard tool for simulating high-velocity bird ingestion in aeroengines, yet LS-DYNA offers fifteen SPH formulations whose relative suitability for multi-stage ingestion has never been systematically assessed. This work presents a comprehensive evaluation of all fifteen formulations, combining (i) a physically representative single-impact benchmark, (ii) a sensitivity analysis of the governing numerical parameters, (iii) a double-impact configuration representative of sequential soft-body loading, and (iv) a validation against experimental data. The single-impact benchmark eliminates five formulations — symmetric (2, 3), adaptive SPH (9, 10), and moving least squares SPH (12) — due to unrealistic deformation, non-physical energy behavior, or core instability, narrowing the field to six candidates: default (0, 1), fluid particle (5, 6), and enhanced fluid (15, 16). Under double-impact loading, only the enhanced fluid formulations, which incorporate density filtering, retain stable shock propagation, coherent deformation, and accurate momentum partitioning; the remaining candidates suffer from either tensile-driven particle blow-up or unphysical clustering. Experimental validation against gelatin bird-surrogate impact tests confirms the predictive accuracy of the enhanced fluid formulations, with the renormalized variant (16) achieving the lowest displacement error and remaining numerically stable over extended computational domains where the standard renormalized formulation becomes computationally intractable. Formulation 16 is identified as the most robust and accurate SPH option for industrial bird-ingestion simulations in LS-DYNA, with formulation 15 offering a lower-cost alternative when computational efficiency outweighs the need for maximal accuracy.