An experimental/theoretical investigation of interfacial instabilities in superposed pressure-driven channel flow of Newtonian and well-characterized viscoelastic fluids

2000 ◽  
Vol 91 (1) ◽  
pp. 85-104 ◽  
Author(s):  
B. Khomami ◽  
Y. Renardy ◽  
K.C. Su ◽  
M.A. Clarke
Keyword(s):  
Channel Flow ◽  
Theoretical Investigation ◽  
Viscoelastic Fluids ◽  
Interfacial Instabilities ◽  
Pressure Driven

Interfacial instabilities in plane Poiseuille flow of two stratified viscoelastic fluids with heat transfer. Part 1. Evolution equation and stability analysis

1995 ◽  
Vol 299 ◽  
pp. 241-265 ◽  
Author(s):  
Sang W. Joo
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Stability Analysis ◽  
Evolution Equation ◽  
Vertical Channel ◽  
Viscoelastic Fluids ◽  
Lubrication Approximation ◽  
Plane Poiseuille Flow ◽  
Interfacial Instabilities ◽  
Different Temperatures

An evolution equation is derived that describes the nonlinear development of the interface between two viscoelastic fluids flowing, under the action of imposed pressure gradient and gravity, in a vertical channel. The channel walls are kept at different temperatures, resulting in heat transfer across the layers. The equation, based on the lubrication approximation, models the effects of stratifications in density, viscosity, elasticity, shear thinning, and thermal conductivity. It also describes the capillary and thermocapillary effects, as well as the sensitivity of viscosities to temperature. Linear-stability analysis is performed based on the evolution equation to understand the competing effects of viscous, elastic, and Marangoni instabilities. Particular attention is paid to the active control of the interfacial instabilities through the thermocapillarity.

Extended Self-Similarity in Drag-Reduced Turbulent Flow of Viscoelastic Fluid

2010 ◽  
Author(s):  
Feng-Chen Li ◽  
Hong-Na Zhang ◽  
Wei-Hua Cai ◽  
Juan-Cheng Yang
Keyword(s):  
Channel Flow ◽  
Viscoelastic Fluid ◽  
Isotropic Turbulence ◽  
Scaling Law ◽  
Viscoelastic Fluids ◽  
Turbulent Channel Flow ◽  
Elastic Model ◽  
Homogeneous Isotropic Turbulence ◽  
Self Similarity ◽  
Extended Self

Direct numerical simulations (DNS) have been performed for drag-reduced turbulent channel flow with surfactant additives and forced homogeneous isotropic turbulence with polymer additives. Giesekus constitutive equation and finite extensible nonlinear elastic model with Peterlin closure were used to describe the elastic stress tensor for both cases, respectively. For comparison, DNS of water flows for both cases were also performed. Based on the DNS data, the extended self-similarity (ESS) of turbulence scaling law is investigated for water and viscoelastic fluids in turbulent channel flow and forced homogeneous isotropic turbulence. It is obtained that ESS still holds for drag-reduced turbulent flows of viscoelastic fluids. In viscoelastic fluid flows, the regions at which δu(r)∝r and Sp(r)∝S3(r)ζ(p) with ζ(p) = p/3, where r is the scale length, δu(r) is the longitudinal velocity difference along r and Sp(r) is the pth-order moment of velocity increments, in the K41 (Kolmogorov theory)-fashioned plots and ESS-fashioned plots, respectively, are all broadened to larger scale for all the investigated cases.

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