A geometric model for helicity evolution in vortex rings

ORAL

Abstract

The helicity of a laminar vortex ring is prescribed by its geometry in the forms of writhe and twist. In viscous fluids, helicity is not conserved, but nonetheless its evolution is naturally characterized by the geometry and topology of the vorticity field. By generating helical vortices using hydrofoils, we are able to measure their helicity and its evolution over a range of Reynolds numbers. Fully resolved DNS with adaptive mesh refinement provide complementary insight. We present an analytic model for helicity evolution in vortex tubes with a natural geometric interpretation and compare its predictions to experiments and simulations.

*This work was funded by U.S. NSF grant DMR-1351506 and Army Research Office grant W911NF-18-1-0046. Additional support was provided by the Chicago MRSEC (U.S. NSF grant DMR 1420709), which is also gratefully acknowledged for access to its shared experimental facilities.

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Presenters

  • Robert Morton

    • James Franck Institute, University of Chicago

Authors

  • Robert Morton

    • James Franck Institute, University of Chicago

  • Xinran Zhao

    • Purdue University

  • Hridesh Kedia

    • Institute for Data Engineering and Science, Georgia Institute of Technology

  • Nicola Lucarelli

    • School of Mechanical Engineering, Purdue University

  • Daniel Peralta-Salas

    • Instituto de Ciencias Matemáticas-ICMAT

  • Carlo Scalo

    • Department of Mechanical Engineering, Purdue University

  • William T Irvine

    • University of Chicago
    • James Franck Institute, Enrico Fermi Institute, University of Chicago