Identify the physical source of the low-pass forcing

Identify whether the effective forcing of the rarefied bow-layer displacement originates from upstream mass-flux fluctuations or from another global numerical or physical input.

Background

The paper models the resolved displacement as a slowly relaxing coordinate driven by broadband forcing. The temporal analysis supports a damped low-pass response, but the available attached-frame upstream proxies do not provide a statistically significant, repeatable forcing signature.

Because the proxies move with the inferred front, they may be contaminated by shock displacement and do not sample a fixed laboratory-frame location. A dedicated fixed upstream sampling plane is therefore required to test whether upstream mass-flux fluctuations drive the response.

References

The present autoregressive fit is the discrete-time counterpart of equation (4.1). It estimates κ* but does not yet identify Sff or prove that the forcing is upstream mass flux rather than another global numerical or physical input.

— Noise-separated evidence for a slow collective displacement in a rarefied hypersonic bow-shock layer  (2608.17285 - Shoja-sani et al., 18 Aug 2026) in Section 4.1, “Relation to stochastic shock-motion models”; Section 4.2, “Frequency-domain and forcing-proxy stress tests”; Appendix C