Laminar supersonic sphere wake unstable bifurcations

Abstract

The laminar sphere unstable bifurcations are sought at a Mach number of M∞ = 1.2. Global stability performed on steady axisymmetric base flows determines the regular bifurcation critical Reynolds number at Re reg cr = 650, identifying a steady planar-symmetric mode to cause the loss of the wake axisymmetry. When global stability is performed on steady planar-symmetric base flows, a Hopf bifurcation is found at Re Hopf cr

Krylov methods for large-scale dynamical systems: Application in fluid dynamics

“…The same methodology has also been employed to compute the leading optimal perturbation [231] in magnetohydrodynamic flows [280], or best exemplified by [35,36] on backward facing steps and stenotic pipe flows. It has also been used to solve high-dimensional Ricatti equations for linear optimal control in [235], or to study the stability properties of flow governed by the compressible Navier-Stokes equations with or without shocks [94,95,226]. These include modal and non-modal stability of compressible boundary layers [49,50,117,125,218], cavities [41,247,253,277], wavepackets in jets [26,192,236], transonic buffet [75-77, 199, 200, 255], including the flow past the NASA Common Research wing Model [254,255], wakes [181] and bluff bodies [163,164,226,227].…”

Investigation of Mach number effects on flow over a flat plate at Reynolds number of 1.0 × 104 by schlieren visualization

“…A study of compressibility effects on the flow dynamics at low-Re flow over basic shapes has been conducted. Flows around a circular cylinder (Canuto andTaira 2015, Nagata et al 2020a), a sphere (Nagata et al 2016, Riahi et al 2018, Sansica et al 2018, Nagata et al 2019, Nagata et al 2020b, Sansica et al 2020, and a NACA airfoil (Morizawa et al 2018) have investigated by experimental and numerical studies. However, there are few studies on the…”