# Taming singularities: yield-stress regularization in bubble-bursting > [!significance] Speaker > [Vatsal Sanjay](https://vatsalsanjay.com) ([CoMPhy Lab](https://comphy-lab.org)) Capillary collapse of a bursting bubble is a canonical inertio-capillary singularity: the retracting rim launches a wave packet that focuses at the cavity base, driving a high-speed Worthington jet and, classically, droplets.  Non-Newtonian physics rewrites this script. For example, yield stress and elasticity tame these waves and the jet and often suppress them [1]. Using high-fidelity simulations carried out with _MultiRheoFlow_ (https://comphy-lab.org/MultiRheoFlow/) $-$ a new open-source Basilisk C framework for interfacial flows with arbitrary rheology $-$ we explore how viscoplasticity and its elastoviscoplastic extension regularizes the singular flow. Yield stress intercepts the collapsing wavepacket, arrests curvature blow-up, and suppresses Worthington jetting [2]. In contrast, elasticity relaxation can reopen a singular path, reinstating a solitary jet or droplet [3]. By tracking curvature histories, kinetic–plastic energy exchange, and stoppage times, we build a compact regime map that exposes the mechanical routes by which non-linear rheology regularizes free-surface singularities.  The findings extend beyond bubbles, offering a template for predicting and controlling singular events in yield-stress and other complex fluids. ![[../_Media/2025-06-30_Conference-VPflow-abstract-1749493868724.png]] Fig. Worthington jet vs. elastoviscoplastic medium, adapted from [1]. > [!info]- Metadata > Posted by:: Vatsal > Date published:: 2025-06-09<br> > Date modified:: Jun 9, 2025 at 20:28 CET > [!meta] Back to main website > [Home](https://comphy-lab.org/), [Team](https://comphy-lab.org/team), [Research](https://comphy-lab.org/research), [Github](https://github.com/comphy-lab) --- ## References [1] A. G. Balasubramanian, V. Sanjay, M. Jalaal, R. Vinuesa, and O. Tammisola, “Bursting bubble in an elasto-viscoplastic medium,” _J. Fluid Mech._, vol. 1001, p. A9, Dec. 2024, doi: [10.1017/jfm.2024.1073](https://doi.org/10.1017/jfm.2024.1073) [2] V. Sanjay, D. Lohse, and M. Jalaal, “Bursting bubble in a viscoplastic medium,” _J. Fluid Mech._, vol. 922, p. A2, 2021, doi: [10.1017/jfm.2021.489](https://doi.org/10.1017/jfm.2021.489) [3] A. K. Dixit, A. Oratis, K. Zinelis, D. Lohse, and V. Sanjay, “Viscoelastic Worthington jets and droplets produced by bursting bubbles,” _J. Fluid Mech._, vol. 1010, p. A2, May 2025, doi: [10.1017/jfm.2025.237](https://doi.org/10.1017/jfm.2025.237). [[2025-06-30_Conference-VPflow-abstract.pdf|this page in .pdf]]