Structural Switching in Crowded Soft Matter

Description para Zenodo Structural Switching in Crowded Soft Matter develops a bounded internal-variable model for nonlinear mass transport in dense soft materials. The framework couples a conserved concentration field to a dynamical structural variable that controls mobility, relaxation, memory, and finite-capacity reorganization of the medium. The model incorporates three physical safeguards: a compact structural restriction map, a saturating transport-induced opening law, and a finite coarse-graining scale associated with the pore or mesh structure of the material. These elements prevent divergent mobilities and unbounded feedback while preserving strict mass conservation. Linear stability analysis predicts a finite-wavelength instability and an intrinsic selected wavelength. Fully coupled two-dimensional simulations starting from weak unbiased noise confirm the predicted growth rate and spatial scale. The selected wavelength remains stable across different domain sizes, non-commensurate and rectangular geometries, numerical resolutions, and random seeds, demonstrating that the resulting pattern is intrinsic to the coupled dynamics rather than imposed by the computational box. Additional sensitivity tests identify distinct regimes of suppressed activation, finite-wave pattern formation, uniform instability, and saturation-controlled hysteresis. The framework is presented as a proof of mechanism for crowded soft matter, polymer networks, hydrogels, and related transport systems with evolving internal structure. It extends a previously published low-diffusivity baseline from a fixed structural parameter to a spatially and temporally evolving structural field. The constitutive design follows the principles of finite capacity, bounded restriction, and local admissibility developed within the Nodal Theory of Everything (TTN), while all equations, stability conditions, simulations, and falsification criteria remain independently testable. This Zenodo record contains the preprint and the associated reproducibility materials, including numerical scripts, figures, convergence tests, parameter sweeps, and machine-readable output files.