Retraction criteria of viscoplastic drops and sheets : long-wave approximations

Hiranya Deka (1) , Jean-Lou Pierson (1) , Edson J. Soares (1, 2)

1 IFPEN - IFP Energies nouvelles
2 UFES - Universidade Federal do Espirito Santo

Retraction dynamics of viscous drops and sheets depend on the relative magnitude of the viscous force over the inertia-capillary force. The dynamics are more complicated in the case of viscoplastic drops/sheets because the yield stress of the fluid also comes into play. The retraction of slender viscoplastic drops and sheets depends on the relative magnitude of the yield stress over the capillary stress. Depending on its relative magnitude, the yield stress can completely resist the retraction. In this study, the retraction of viscoplastic drops and sheets has been investigated theoretically neglecting the effect of the surrounding medium. Using long-wave theory we derive the retraction criteria of slender drops (axisymmetric) and sheets (two-dimensional) for yield stress fluids. Direct numerical simulations are also performed by solving the complete momentum conservation equations. A good agreement is found between the numerical results and the proposed retraction

Mots clés: Viscoplastic fluid; Capillary flow; Long-wave theory; Retraction

Domaines: Sciences de l'environnement

Hiranya Deka, Jean-Lou Pierson, Edson J. Soares. Retraction criteria of viscoplastic drops and sheets : long-wave approximations. Journal of Non-Newtonian Fluid Mechanics, 2020, 284, pp.104352. ⟨10.1016/j.jnnfm.2020.104352⟩. ⟨hal-02959259⟩