Radial-flow fluctuations are discussed using the $p_{\mathrm{T}}$-differential measure $v_0\left(p_{\mathrm{T}}\right)$, together with its $p_{\mathrm{T}}$-integrated counterpart $v_0$, within the framework of geometrical scaling (GS), where the saturation momentum scale provides the characteristic scale for particle production. It is shown that the GS framework leads to results similar to those obtained from the momentum-rescaling model proposed by [J. Jia, Phys. Rev. Lett. 136, 112301 (2026)]. In the GS picture, event-by-event spectral fluctuations are governed by fluctuations of the saturation momentum scale; consequently, the single-mode ansatz introduced in Jia's model emerges naturally. The GS picture also suggests a possible connection between transverse-momentum correlations and fluctuations of the emission region, which may be probed through Hanbury-Brown and Twiss analyses. Using the string percolation model, which is closely related to GS, the multiplicity dependence of radial-flow fluctuations is estimated, and the scaled quantity $A_0\left(N_{\mathrm{\Delta }y}\right)\equiv v_0^2{N}_{\mathrm{\Delta }y}$, with $N_{\mathrm{\Delta }y}=(dN/dy)\mathrm{\Delta }y$, is proposed as a diagnostic observable for testing the role of effective flux-tube fluctuations.

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• Collective flow
• Particle correlations & fluctuations
• Quark-gluon plasma