Surface tension, not gravity, governs circular hydraulic jumps at kitchen-sink scales

Mallik et al. measured film thickness inside and outside the jump using laser-induced fluorescence and capacitance probes while varying jet flow rate, nozzle height, and fluid properties. These data supplied direct estimates of local Weber, Froude, and Reynolds numbers. Matched volume-of-fluid simulations reproduced the measured jump radius and height profiles to within 5 percent, confirming that surface tension sets the jump location once inertia and viscosity are accounted for. A critical dimensionless flow rate was identified beyond which gravity regains influence and the jump radius scales differently. The work supplies the first quantitative separation of surface-tension versus gravity regimes for the axisymmetric hydraulic jump under realistic sink conditions. Prior analytic models assumed gravity dominance; the new measurements overturn that assumption for typical household flows. Extension to non-Newtonian or surfactant-laden liquids would test whether the Weber-order-unity criterion remains universal.