Scale-Dependent Velocity Coherence in the Laniakea Region: A Phenomenological Interpretation of Late-Time Flow Relaxation

This preprint presents a scale-dependent analysis of peculiar velocity coherence in the region commonly associated with the Laniakea supercluster, using reconstructed velocity fields derived from Cosmicflows / CF4 data. Rather than treating Laniakea as a dynamically bound overdensity, the paper interprets it as a velocity-defined mesoscale flow domain, characterised by coherent motion that peaks at intermediate scales and decays rapidly beyond ~200 Mpc. The analysis focuses on observationally grounded measures of velocity coherence, including bulk-flow and RMS peculiar velocity amplitudes evaluated as a function of radius. A simple phenomenological framework is introduced to quantify how coherence changes with spatial scale, without invoking modified gravity, global anisotropy, or new dynamical degrees of freedom. The results indicate a preferred mesoscale for velocity coherence consistent with incomplete late-time relaxation of large-scale flows. This work is released publicly as a preprint to invite open examination and independent evaluation. It has not been submitted for journal peer review. All assumptions, methodological choices, and limitations are stated explicitly in the manuscript, and no claims are made beyond those supported by the presented analysis. The document includes a transparency statement, an AI assistance disclosure, and clear scope limitations. Readers are encouraged to assess the work on its technical merits, internal consistency, and empirical grounding. This preprint is intended as a contribution to open scientific discussion rather than as a definitive or exhaustive treatment of the subject. Companion paper:Readers interested in the broader phenomenological framework underlying this analysis may wish to consult Field–Matter Slip as a Unified Origin of Late-Time Cosmological Anisotropies (Zenodo: https://zenodo.org/records/18377318). Note on Related Intellectual Property:A related conceptual framework has been disclosed in a provisional patent application filed with the United States Patent and Trademark Office. The present preprint does not describe an engineering system, does not claim applicability to propulsion or device construction, and is intended solely as an observational and phenomenological analysis of reconstructed cosmological velocity fields.