Invisible Anchors Trap Particles in Branching Junctions. Author David Oettinger, Jesse Ault, Howard Stone, George Haller Publication Year 2018 Type Journal Article Abstract We combine numerical simulations and an analytic approach to show that the capture of finite, inertial particles during flow in branching junctions is due to invisible, anchor-shaped three-dimensional flow structures. These Reynolds-number-dependent anchors define trapping regions that confine particles to the junction. For a wide range of Stokes numbers, these structures occupy a large part of the flow domain. For flow in a V-shaped junction, at a critical Stokes number, we observe a topological transition due to the merger of two anchors into one. From a stability analysis, we identify the parameter region of particle sizes and densities where capture due to anchors occurs. Journal Phys Rev Lett Volume 121 Issue 5 Pages 054502 Date Published 2018 Aug 03 ISSN Number 1079-7114 DOI 10.1103/PhysRevLett.121.054502 Alternate Journal Phys Rev Lett PMID 30118271 PubMedGoogle ScholarBibTeXEndNote X3 XML