Segregation transitions in wet granular matter

We report the effect of interstitial fluid on the extent of segregation by imaging the pile that results after bidisperse color-coded particles are poured into a silo. Segregation is sharply reduced and preferential clumping of small particles is observed when a small volume fraction of fluid \(V_f\) is added. We find that viscous forces in addition to capillary forces have an important effect on the extent of segregation \(s\) and the angle of repose \(\theta\). We show that the sharp initial change and the subsequent saturation in \(s\) and \(\theta\) occurs over similar \(V_f\). We also find that a transition back to segregation can occur when the particles are completely immersed in a fluid at low viscosities.