An Experimental Study of Turbulent Non-Newtonian Fluid Flow in Concentric Annuli using Particle Image Velocimetry Technique

Extreme-Point Symmetric Mode Decomposition to Define the Turbulence Characteristics of a Flume Flow

“…e relative turbulence intensity (TI), Reynolds shear stress (τ ij ), and turbulent kinetic energy (TKE) are the most commonly used indexes in practice [15,17]. e parameters can be calculated as follows:…”

Study of the Hydrodynamic Characteristics of Non‐Newtonian Polymer Solution Fluid in Concentric Annulus Using Computational Fluid Dynamics Methods

“…As recommended by Bizhani et al., the Carreau rheology model is the best choice for measuring viscosity data. [ 4 ]…”

“…For example, the flow pattern can be characterized by the Reynolds number, which is related to the hydraulic diameter and wall viscosity $$\begin{equation}{\mathop{\rm Re}\nolimits} = \frac{{\rho {U_{\rm{B}}}{D_{\rm{H}}}}}{{{\eta _{\rm{w}}}}}\end{equation}$$where U B is the bulk velocity, D H is the hydraulic diameter defined as D o − D i , and η w is the wall viscosity. The average wall shear stress τ A can be calculated using the frictional pressure loss [ 4 ] $$\begin{equation}{\tau _{\rm{A}}} = \frac{1}{4}{D_{\rm{H}}}\frac{{dp}}{{dx}}\end{equation}$$…”

“…Concentric annulus employed in oil drilling and heat exchange operations have been widely used in petroleum chemical industry. [ 1–4 ] In contrast to symmetric pipe flow, hydrodynamic behaviors in annuli have many complex features, including asymmetric velocity distribution and nonlinear decay of shear stress with distance from the inner and outer walls. In particular, when a non‐Newtonian liquid is the work fluid, the complexity of fluid flow is further increased because of the variable rheological properties.…”

“…[ 11–13 ] By comparison, advanced experimental techniques, such as laser Doppler anemometry and particle image velocimetry, have been widely used to investigate the velocity characteristics of non‐Newtonian fluids in a concentric annulus. [ 4,14–17 ] Based on the measured data, the detailed flow characteristics can be obtained by postprocessing procedures, including mean velocity, velocity fluctuation, shear stress, and turbulence intensity, which help understand the flow mechanics of non‐Newtonian fluids. Additionally, numerical simulations have become a critical tool for investigating the hydrodynamic characteristics and heat transfer performance of a concentric annulus.…”