3 papers
physics.flu-dyn2026
Analysis of inviscid shear instability of axisymmetric flows
Kengo Deguchi, Haider Munawar, Runjie Song
Simple analytical criteria are derived to determine whether axisymmetric base flows in annuli and pipes are stable or unstable. Both axisymmetric and non-axisymmetric inviscid dist…
physics.flu-dyn2026
Multiscale quasi time-periodic coherent structures in shear flows
Runjie Song, Kengo Deguchi, Genta Kawahara +1
Attempts to disentangle shear-flow turbulence often focus on identifying relatively simple solutions, such as travelling waves or periodic orbits. We show, however, that capturing…
physics.flu-dyn2026
Beyond secondary instability: on the emergence of finite-amplitude waves in Görtler vortices
Runjie Song, Kengo Deguchi
Görtler vortices developing over a concave wall support rapidly oscillating wavelike disturbances through secondary instabilities. Although experiments indicate that the finite-am…