A reverse transition route from inertial to elasticity-dominated turbulence in viscoelastic Taylor–Couette flow

2021 ◽  
Vol 927 ◽  
Author(s):  
Jiaxing Song ◽  
Zhen-Hua Wan ◽  
Nansheng Liu ◽  
Xi-Yun Lu ◽  
Bamin Khomami
Keyword(s):  
Laminar Flow ◽  
Shear Flows ◽  
Scaling Law ◽  
Polymer Concentration ◽  
Chain Extension ◽  
Flow State ◽  
Reverse Transition ◽  
Parallel Shear Flows ◽  
Taylor Couette ◽  
Hoop Stresses

A high-order transition route from inertial to elasticity-dominated turbulence (EDT) in Taylor–Couette flows of polymeric solutions has been discovered via direct numerical simulations. This novel two-step transition route is realized by enhancing the extensional viscosity and hoop stresses of the polymeric solution via increasing the maximum chain extension at a fixed polymer concentration. Specifically, in the first step inertial turbulence is stabilized to a laminar flow much like the modulated wavy vortex flow. The second step destabilizes this laminar flow state to EDT, i.e. a spatially smooth and temporally random flow with a $-3.5$ scaling law of the energy spectrum reminiscent of elastic turbulence. The flow states involved are distinctly different to those observed in the reverse transition route from inertial turbulence via a relaminarization of the flow to elasto-inertial turbulence in parallel shear flows, underscoring the importance of polymer-induced hoop stresses in realizing EDT that are absent in parallel shear flows.

scholarly journals Exact coherent structures in an asymptotically reduced description of parallel shear flows

2014 ◽  
Vol 47 (1) ◽  
pp. 015504 ◽  
Author(s):  
Cédric Beaume ◽  
Edgar Knobloch ◽  
Gregory P Chini ◽  
Keith Julien
Keyword(s):  
Coherent Structures ◽  
Shear Flows ◽  
Parallel Shear Flows

Extension of classical stability theory to viscous planar wall-bounded shear flows

2019 ◽  
Vol 877 ◽  
pp. 1134-1162 ◽  
Author(s):  
Harry Lee ◽  
Shixiao Wang
Keyword(s):  
Boundary Conditions ◽  
Shear Flows ◽  
Early Stage ◽  
Linear Instability ◽  
Slip Condition ◽  
Translation Invariant ◽  
Alternative Derivation ◽  
Wall Boundary ◽  
Wall Boundary Conditions ◽  
Parallel Shear Flows

A viscous extension of Arnold’s inviscid theory for planar parallel non-inflectional shear flows is developed and a viscous Arnold’s identity is obtained. Special forms of the viscous Arnold’s identity have been revealed that are closely related to the perturbation’s enstrophy identity derived by Synge (Proceedings of the Fifth International Congress for Applied Mechanics, 1938, pp. 326–332, John Wiley) (see also Fraternale et al., Phys. Rev. E, vol. 97, 2018, 063102). Firstly, an alternative derivation of the perturbation’s enstrophy identity for strictly parallel shear flows is acquired based on the viscous Arnold’s identity. The alternative derivation induces a weight function. Thereby, a novel weighted perturbation’s enstrophy identity is established, which extends the previously known enstrophy identity to include general streamwise translation-invariant shear flows. Finally, the validity of the enstrophy identity for parallel shear flows is rigorously examined and established under global nonlinear dynamics imposed with two classes of wall boundary conditions. As an application of the enstrophy identity, we quantitatively investigate the mechanism of linear instability/stability within the normal modal framework. The investigation reveals a subtle interaction between a critical layer and its adjacent boundary layer, which determines the stability nature of the disturbance. As an implementation of the relaxed wall boundary conditions imposed for the enstrophy identity, a control scheme is proposed that transitions the wall settings from the no-slip condition to the free-slip condition, through which a flow is stabilized quickly in an early stage of the transition.

A proof of Howard’s conjecture in homogeneous parallel shear flows

1994 ◽  
Vol 104 (3) ◽  
pp. 593-595 ◽  
Author(s):  
Mihir B Banerjee ◽  
R G Shandil ◽  
Vinay Kanwar
Keyword(s):  
Shear Flows ◽  
Parallel Shear Flows

Aerodynamic Effects of Inviscid Parallel Shear Flows

AIAA Journal ◽  
1977 ◽  
Vol 15 (8) ◽  
pp. 1159-1166 ◽  
Author(s):  
M. H. Williams ◽  
M. R. Chi ◽  
C. S. Ventres ◽  
E. H. Dowell
Keyword(s):  
Shear Flows ◽  
Parallel Shear Flows

Numerical Simulation on Oil-Flow-State of Gap Oil Film in Sector Cavity Multi-Pad Hydrostatic Thrust Bearing

2010 ◽  
Vol 37-38 ◽  
pp. 743-747
Author(s):  
Xiao Dong Yu ◽  
Xiu Li Meng ◽  
Hui Jiang ◽  
Xiao Zhong Lou ◽  
Bo Wu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Laminar Flow ◽  
Critical Speed ◽  
Thrust Bearing ◽  
Lubricating Oil ◽  
Good Effect ◽  
Critical Flow ◽  
Flow State ◽  
Oil Film ◽  
Oil Flow

Hydrostatic thrust bearing lubrication is significantly affected by the oil flow state of gap oil film, but it can not be measured by experiment and analysis. For this problem, the oil flow state of gap oil film in sector cavity multi-pad hydrostatic thrust bearing during rotation was simulated by using computational fluid dynamics, lubricating theory, and Finite Element Method. Laminar model and κ-ε turbulence model were adopted to model incompressible steady equations, and the equations were discreted by using Finite Volume Method and Second-order Finite Difference. By comparing the calculated results of numerical simulation and semi-empirical theoretical equation, the numerical simulation is proved feasible in oil film state analysis parameter prediction, which can overcome the deficiency of single model and get good effect. Streamlines and velocity vectors show that the lubricating oil flow in the resistive oil edges and oil cavities are laminar flow under the conditions of speed and flow in less than a certain value, while the flow and speed are more than a certain value, the lubricating oil flow in the resistive oil edges is also laminar flow, but the lubricating oil flow in the oil cavities is turbulent flow, then determines critical flow and critical speed. The critical flow and critical speed were determined, it provides a theoretical basis of the temperature field and thermal field deformation calculation.

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