Can nonlinear elasticity explain contact-line roughness at depinning?

Journal article

We examine whether cubic nonlinearities, allowed by symmetry in the elastic energy of a contact line, may result in a different universality class at depinning. Standard linear elasticity predicts a roughness exponent zeta = 1/3 (one loop), zeta = 0.388 +/- 0.002 (numerics) while experiments give zeta approximately = 0.5. Within functional renormalization group methods we find that a nonlocal Kardar-Parisi-Zhang-type term is generated at depinning and grows under coarse graining. A fixed point with zeta approximately = 0.45 (one loop) is identified, showing that large enough cubic terms increase the roughness. This fixed point is unstable, revealing a rough strong-coupling phase. Experimental study of contact angles theta near pi/2, where cubic terms in the energy vanish, is suggested.

Authors: Le Doussal, P; Wiese, K; Raphael, E; Golestanian, R

• Publication status: Published
• Journal: Physical Review Letters
• Volume: 96
• Issue: 1
• Pages: 015702
• Publication date: 2006-01-01
• DOI: 10.1103/physrevlett.96.015702
• EISSN: 1079-7114
• ISSN: 0031-9007
• Language: English
• Keywords: cond-mat.dis-nn; cond-mat.soft