{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T12:58:57Z","timestamp":1790859537963,"version":"4.1.0"},"reference-count":25,"publisher":"AIP Publishing","issue":"10","content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2026,10,1]]},"abstract":"<jats:p>Dense granular media lack a well-established analog of classical liquid tensiometry, although localized interfacial barriers can strongly influence segregation, buoyancy, and intruder stability. Using a calibrated dual-mode orbital calorimeter\u2013rheometer, we show that a partially submerged intruder can serve as an in situ mechanical probe of the grain-mediated restoring response in an orbitally driven dense bed. In the rigid-body core-rotation regime at low peak acceleration, \u0393=2.5, and low granular temperature, Tg\u224810\u22127m2s\u22122, the intruder follows a stable circular orbit with negligible radial drift and intrinsic spin. This kinematic state indicates that the inward centripetal force required in the laboratory frame is balanced predominantly by a localized restoring interaction associated with the air\u2013grain\u2013intruder contact configuration. By combining the measured density-contrast centrifugal demand with the specific interfacial area of the ternary bead mixture and a geometry-calibrated effective radial transmission area, we obtain an effective granular interfacial-stress scale of \u03b3gm\u22482.38\u00d710\u22122Jm\u22122. The inferred value agrees within 1.2% with an independently obtained thermomechanical reference at the corresponding low granular temperature. The result provides a mechanical explanation for the granular Archimedean anomaly, in which the intruder remains stably surface supported while the displaced granular volume supplies less than half of its static weight under a conventional hydrostatic estimate. At the fluidization threshold, \u0393=6.02, kinetic thermalization raises the granular temperature to Tg\u224810\u22124m2s\u22122; the localized restoring configuration is then destabilized, and the intruder exhibits orientation instability, rapid inward migration, intrinsic rotation, and deep convective submersion. A 10\u2009000-trial Monte Carlo analysis yields a coefficient of variation of \u223c3.4% under realistic composition tolerances. These results establish a non-invasive, trajectory-based methodology for quantifying an effective localized granular interfacial-stress scale in actively driven dense particulate systems.<\/jats:p>","DOI":"10.1063\/5.0344099","type":"journal-article","created":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T12:32:08Z","timestamp":1790857928000},"update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":0,"title":["Measuring effective surface energy in non-equilibrium granular fluids using an innovative orbital tensiometer apparatus"],"prefix":"10.1063","volume":"97","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0683-4941","authenticated-orcid":false,"given":"Piroz","family":"Zamankhan","sequence":"first","affiliation":[{"name":"Arctic Greenhouse Research Unit (AGRU) , Ounasjoen itapuolentie 5617, 97340 Meltaus,","place":["Finland"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"317","published-online":{"date-parts":[[2026,10,1]]},"reference":[{"key":"2026100108320001200_c1","volume-title":"Fluid Mechanics","year":"2011","edition":"7"},{"key":"2026100108320001200_c2","volume-title":"Principles of Thermodynamics","year":"1975"},{"key":"2026100108320001200_c3","volume-title":"Surface Tension and Related Thermodynamic Quantities of Aqueous Electrolyte Solutions","year":"2013"},{"key":"2026100108320001200_c4","doi-asserted-by":"publisher","first-page":"521","DOI":"10.1085\/jgp.7.5.625","article-title":"An interfacial tensiometer for universal use","volume":"1","year":"1919","journal-title":"J.\u00a0Gen. 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