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Stability of particle clusters bound by capillary bridges in extensional flow

Sagar Chaudhary

Dimitrios Fraggedakis* and Charles M. Schroeder†

  • Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08540, USA

  • *Contact author: dfrag@princeton.edu
  • †Contact author: cschroeder@princeton.edu
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Phys. Rev. Fluids 11, L032301 – Published 17 March, 2026

DOI: https://doi.org/10.1103/g9nd-jlc9

Abstract

Capillary suspensions are commonly encountered in a wide array of applications, but their stability in flow is not fully understood. Here, we investigate the stability of a two-particle capillary cluster in extensional flow using a combination of theory and experiments. A linear stability analysis reveals the existence of a critical capillary number Cac=(8/45)cosθ that depends only on the contact angle θ. For Ca>Cac, clusters are unconditionally unstable, regardless of initial conditions. For Ca < Cac, a nonlinear analysis shows the existence of a Ca-dependent minimum interparticle separation beyond which breakup occurs. The analytical model further supports the experimentally observed slowdown in relaxation dynamics. Theoretical predictions are supported by precise flow experiments using a Stokes trap, where active flow modulation is used to stabilize an initially unstable cluster in extensional flow. Overall, these results provide a quantitative understanding of capillary suspension stability in flow.

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Phys. Rev. Fluids 11, L032301– Published 17 March, 2026
  • Received 29 August 2025
  • Accepted 30 January 2026
Article part of CHORUS
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