Fluid Mechanics
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Fluid mechanics

  • Hydraulic jumps
  • Flow in flexible tubes
  • Two-phase flow
  • Hydraulic jumps

    A hydraulic jump is an easily recognized classical phenomenon in fluid mechanics. Nevertheless, its rich and complex nature is not completely understood to this day. Fascinating multi-dimensional and unsteady features of hydraulic jumps, in particular, the formation of polygonal structures (see pictures below, taken from J. Bush's website) are awaiting for their good theoretical explanations.


    Jump radius as a function of the flow rate: comparison between theory and experiment (experimental data kindly provided by John Bush and Jeff Aristoff.)

    A. R. Kasimov, A stationary circular hydraulic jump, the limits of its existence and its
    gasdynamic analogue, 2008, Journal of Fluid Mechanics, 601, 189-198 (PDF).
    In this work, I have developed a theoretical model of a steady-state circular hydraulic jump, which in a simplified manner accounts for viscous losses, surface tension, and bottom topography and allows for prediction of the jump radius in a completely rational manner, i.e. without any fitting or empirical parameters. An analogy is drawn between the hydraulic jump and a self-sustained detonation wave based on the observation that both of these structures represent a shock wave followed by a transcritical/transonic flow. In both cases, the existence of a sonic point is crucial in determining an important feature of the structure - the wave speed in detonation and the jump radius in the hydraulic jump.