Jingbang Liu

• Dhaliwal, Runepal Singh Sørensen; Liu, Jingbang & Carlson, Andreas (2025). Stochastic elastohydrodynamics of contact and coarsening during membrane adhesion. Journal of Fluid Mechanics. ISSN 0022-1120. 1024. doi: 10.1017/jfm.2025.10872. Full text in Research Archive Show summary

  Contact between fluctuating, fluid-lubricated soft surfaces is prevalent in engineering and biological systems, a process starting with adhesive contact, which can give rise to complex coarsening dynamics. One representation of such a system, which is relevant to biological membrane adhesion, is a fluctuating elastic interface covered by adhesive molecules that bind and unbind to a solid substrate across a narrow gap filled with a viscous fluid. This flow is described by the stochastic elastohydrodynamic thin film equation, which incorporates thermal fluctuations into the description of viscous nanometric thin-film flow coupled to elastic membrane deformation. The average time it takes the fluctuating elastic membrane to adhere is predicted by the rare event theory, increasing exponentially with the square of the initial gap height. When the forces arising from spring-like adhesive molecules are included in the simulations, thermal fluctuations initiate phase separation of domains of bound and unbound molecules. The coarsening process of these unbound pockets displays close similarities to classical Ostwald ripening; however, the inclusion of hydrodynamics affects power-law growth. In particular, we identify a new bending-dominated coarsening regime, which is slower than the well-known tension-dominated case.

• Liu, Jingbang; Sprittles, James E. & Grafke, Tobias (2024). Mean first passage times and Eyring-Kramers formula for fluctuating hydrodynamics. Journal of Statistical Mechanics: Theory and Experiment. 2024(10). doi: 10.1088/1742-5468/ad8075. Full text in Research Archive Show summary

  Thermally activated phenomena in physics and chemistry, such as conformational changes in biomolecules, liquid film rupture, or ferromagnetic field reversal, are often associated with exponentially long transition times described by Arrhenius’ law. The associated subexponential prefactor, given by the Eyring–Kramers formula, has recently been rigorously derived for systems in detailed balance, resulting in a sharp limiting estimate for transition times and reaction rates. Unfortunately, this formula does not trivially apply to systems with conserved quantities, which are ubiquitous in the sciences: The associated zeromodes lead to divergences in the prefactor. We demonstrate how a generalised formula can be derived, and show its applicability to a wide range of systems, including stochastic partial differential equations from fluctuating hydrodynamics, with applications in rupture of nanofilm coatings and social segregation in socioeconomics.

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