8 citations · 42 across the 11 of their papers we have counts for
12 papers
Stratified jet with wall effects
Hai Duc Vu, Kengo Deguchi
Jets in stratified flows are ubiquitous in geophysics. A fundamental question is whether the instabilities and coherent structures generated by the flow interact with the physical…
Spatial marching with subgrid-scale local exact coherent structures in non-uniformly curved channel flow
Runjie Song, Kengo Deguchi
We propose a novel multiple-scale spatial marching method for flows with slow streamwise variation. The key idea is to couple the boundary region equations, which govern large-scal…
Linear and nonlinear instabilities in highly shear thinning fluid flow through a pipe
Xuerao He, Kengo Deguchi, Runjie Song +1
Shear-thinning fluids flowing through pipes are crucial in many practical applications, yet many unresolved problems remain regarding their turbulent transition. Using highly robus…
Instability in centrifugally stable shear flows
Kengo Deguchi, Ming Dong
We investigate the linear instability of flows that are stable according to Rayleigh's criterion for rotating fluids. Using Taylor-Couette flow as a primary test case, we develop l…
Three-dimensional coherent structures in a curved pipe flow
Runjie Song, Kengo Deguchi
Dean's approximation for curved pipe flow, valid under loose coiling and high Reynolds numbers, is extended to study three-dimensional travelling waves. Two distinct types of solut…
A sufficient condition for inviscid shear instability: Hurdle theorem and its application to alternating jets
Kengo Deguchi, Makoto Hirota, Timothy Dowling
We propose a simple method to identify unstable parameter regions in general inviscid unidirectional shear flow stability problems. The theory is applicable to a wide range of basi…
On high Taylor number Taylor vortices
Kengo Deguchi
Axisymmetric steady solutions of Taylor-Couette flow at high Taylor numbers are studied numerically and theoretically. As the axial period of the solution shortens from about one g…
Eigenvalue bounds for compressible stratified magneto-shear flows varying in two transverse directions
Kengo Deguchi
Three eigenvalue bounds are derived for the instability of ideal compressible stratified magnetohydrodynamic shear flows in which the base velocity, density, and magnetic field var…
Fully nonlinear mode competitions in magnetised Taylor-Couette flow
R. Ayats, K. Deguchi, F. Mellibovsky +1
We study the nonlinear mode competition of various spiral instabilities in magnetised Taylor-Couette flow. The resulting finite-amplitude mixed-mode solution branches are tracked u…
High-speed standard magneto-rotational instability
Kengo Deguchi
The large Reynolds number asymptotic approximation of the neutral curve of Taylor-Couette flow subject to axial uniform magnetic field is analysed. The flow has been extensively st…
High-speed shear driven dynamos. Part 2. Numerical analysis
Kengo Deguchi
This paper aims to numerically verify the large Reynolds number asymptotic theory of magneto-hydrodynamic (MHD) flows proposed in the companion paper Deguchi (2019). To avoid any c…
High-speed shear driven dynamos. Part 1. Asymptotic analysis
Kengo Deguchi
Rational large Reynolds number matched asymptotic expansions of three-dimensional nonlinear magneto-hydrodynamic (MHD) states are concerned. The nonlinear MHD states, assumed to be…