Planar hydraulic jumps in thin film flow

Jetting in finite-amplitude, free, capillary-gravity waves

“…(2018), Lai et al. (2018), Singh, Farsoiya & Dasgupta (2019), Blanco-Rodríguez & Gordillo (2020) and Dhar, Das & Das (2020), to mention only a small set. Basilisk implements the finite-volume algorithm using the Bell–Collela–Glaz (Bell, Colella & Glaz 1989) advection scheme.…”

Internal hydraulic jump in plane Poiseuille two-layer flow: theoretical, numerical and experimental study

“…The continuity and momentum balance equations are formulated for stratified flow of a thin liquid film and gas flowing above the liquid in a 2-D planar geometry. The effect of surface tension is assumed negligible compared to gravity (Kate, Das & Chakraborty 2007;Dhar et al 2020), since surface tension has been reported to influence jump stability (Bohr et al 1997;Watanabe et al 2003), which is not the focus of the present paper. We also neglect the entry effect and assume negligible dissipation of streamwise compared to transverse momentum.…”

“…A common yet hitherto unexplored flow phenomenon is 'planar internal hydraulic jump in thin films', where viscous dissipation decelerates laminar flow from supercritical (Fr > 1, where Fr is Froude number) to subcritical (Fr < 1) conditions, resulting in an abrupt elevation of the interface. Such jumps, commonly termed 'natural hydraulic jumps' in the literature (Dasgupta, Tomar & Govindarajan 2015;Dhar, Das & Das 2020) have received scant attention even for single phase flows. Most of the studies (Higuera 1994;Bohr, Putkaradze & Watanabe 1997;Watanabe, Putkaradze & Bohr 2003;Singha, Bhattacharjee & Ray 2005) are influenced by the extensive literature on circular hydraulic jumps (Tani 1949;Watson 1964;Bohr, Dimon & Putkaradze 1993;Higuera 1997), which form when a vertical liquid jet impinges on a horizontal plane and spreads radially as a thin film.…”

“…In single phase flows, this problem is addressed using shallow water theory (SWT), an approximate analysis where the averaged momentum balance equation is obtained from vertical integration of the simplified Navier-Stokes equations across the flow. The equation is further simplified to obtain the evolution of liquid height or average velocity in the streamwise direction, either by assuming self-similar velocity profiles in the liquid film (Singha et al 2005;Dhar et al 2020) or by considering varying profile where additional inputs are required for closure of the model (Bohr et al 1997;Watanabe et al 2003;Bonn, Anderson & Bohr 2009). In the present problem, the additional shear due to simultaneous two-layer flow modifies the velocity profile and none of the approaches can be directly applied for solving Navier-Stokes equations.…”

“…Since the experiments are performed primarily for validation, the test rig has been ingenuously designed such that shear induced jump forms inside a two-dimensional (2-D) geometry during simultaneous air-water flow and the liquid film is 'thin' enough to remain laminar even after the jump for a wide range of flow conditions. To the best of the authors' knowledge, experiments on films which remain laminar after the jump have hardly been reported for single phase flows (Dhar et al 2020), let alone two phase flow situations.…”