Effects of radius ratio on turbulent concentric annular pipe flow and structures

2020 ◽  
Vol 86 ◽  
pp. 108725
Author(s):  
Edris Bagheri ◽  
Bing-Chen Wang
Keyword(s):  
Pipe Flow ◽  
Radius Ratio ◽  
Annular Pipe

A liquid plug moving in an annular pipe—Flow analysis

2018 ◽  
Vol 30 (9) ◽  
pp. 093605 ◽  
Author(s):  
Yadi Cao ◽  
Ri Li
Keyword(s):  
Pipe Flow ◽  
Flow Analysis ◽  
Liquid Plug ◽  
Annular Pipe

scholarly journals The Development of Swirling Decaying Laminar Flow in an Annular Pipe

2018 ◽  
Vol 51 ◽  
pp. 03001
Author(s):  
Baiman Chen ◽  
Frank G.F. Qin ◽  
Youyuan Shao ◽  
Hanmin Xiao ◽  
Simin Huang ◽  
...  
Keyword(s):  
Turbulent Flows ◽  
Pipe Flow ◽  
Tangential Component ◽  
Duct Flow ◽  
Mean Flow ◽  
Entry Length ◽  
Swirl Angle ◽  
Practical Engineering ◽  
Inlet Swirl ◽  
Annular Pipe

Work on the hydrodynamic entry length of pipe and duct flow has been well studied over the years. The assumption of fully developed flows is commonly used in many practical engineering applications (e.g. Moody's chart). For laminar axial pipe flow, the hydrodynamic entry length can be found through the monomial proposed by Kays, Shah and Bhatti (KSB) (Lh=0.056ReDh). In contrast, several approximations exist for fully turbulent flows (i.e. 10Dh-150Dh). Through theoretical and numerical investigations, the hydrodynamic entry length for swirling decaying pipe flow in the laminar regime is investigated. It was found that, the development length Lh for the axial velocity profile changes when a tangential component is added to the mean flow. The reduction in the hydrodynamic length was found to be dependent on the inlet swirl angle θ. The results indicate that a modification can be made on the KSB equation for two-dimensional swirling annular pipe flow.

scholarly journals Patterns in Wall-Bounded Shear Flows

2020 ◽  
Vol 52 (1) ◽  
pp. 343-367 ◽  
Author(s):  
Laurette S. Tuckerman ◽  
Matthew Chantry ◽  
Dwight Barkley
Keyword(s):  
Numerical Simulations ◽  
Couette Flow ◽  
Poiseuille Flow ◽  
Pipe Flow ◽  
Shear Flows ◽  
Plane Couette Flow ◽  
Plane Poiseuille Flow ◽  
Flow Focusing ◽  
Annular Pipe ◽  
Flow Plane

Experiments and numerical simulations have shown that turbulence in transitional wall-bounded shear flows frequently takes the form of long oblique bands if the domains are sufficiently large to accommodate them. These turbulent bands have been observed in plane Couette flow, plane Poiseuille flow, counter-rotating Taylor–Couette flow, torsional Couette flow, and annular pipe flow. At their upper Reynolds number threshold, laminar regions carve out gaps in otherwise uniform turbulence, ultimately forming regular turbulent–laminar patterns with a large spatial wavelength. At the lower threshold, isolated turbulent bands sparsely populate otherwise laminar domains, and complete laminarization takes place via their disappearance. We review results for plane Couette flow, plane Poiseuille flow, and free-slip Waleffe flow, focusing on thresholds, wavelengths, and mean flows, with many of the results coming from numerical simulations in tilted rectangular domains that form the minimal flow unit for the turbulent–laminar bands.

Turbulent Annular Pipe Flow in Subcritical Transition Regime: Direct Numerical Simulation of a Large Domain

2015 ◽  
Author(s):  
Takahiro Ishida ◽  
Takahiro Tsukahara
Keyword(s):  
Reynolds Number ◽  
Poiseuille Flow ◽  
Reynolds Numbers ◽  
Radius Ratio ◽  
Transition Regime ◽  
Transitional Regime ◽  
Large Domain ◽  
High Reynolds ◽  
Annular Pipe ◽  
Transition Scenario

We performed direct numerical simulations of annular Poiseuille flow (APF) with a radius ratio of η (= rin/rout) = 0.8, in order to investigate the subcritical transition scenario from the developed turbulent state to the laminar state. In previous studies on annular Poiseuille flow, the flows at high Reynolds numbers were well examined and various turbulence statistics were obtained for several η, because of their dependence on η. Since the transitional APF is still unclear, we investigate annular Poiseuille flows in the transitional regime through the large-domain simulations in a range of the friction Reynolds number from Reτ = 150 down to 56. At a transitional Reynolds number, weak-fluctuation regions occur intermittently and regularly in the flow field, and the localized turbulence appears in the form of banded patterns same as in plane Poiseuille flow (PPF). The flow system of APF with a high radius ratio η ≈ 1 can be regarded as PPF and, hence, the transition regime in high radius-ratio of APF and in PPF should be analogous. However, in APF, the banded structure takes on helical shape around the inner cylinder, since APF is a closed system in the spanwise (azimuthal) direction. In this paper, the (dis-)similarity between APF and PPF is discussed.

An Experimental Study of the Effect of Drag Reducing Additive on the Structure of Turbulence in Concentric Annular Pipe Flow Using Particle Image Velocimetry Technique

2013 ◽  
Author(s):  
Fabio Ernesto Rodriguez Corredor ◽  
Majid Bizhani ◽  
Ergun Kuru
Keyword(s):  
Particle Image Velocimetry ◽  
Fluid Flow ◽  
Pipe Flow ◽  
Particle Image ◽  
Polymer Concentration ◽  
Velocity Fluctuations ◽  
Polymer Fluid ◽  
Image Velocimetry ◽  
Drag Reducing Additive ◽  
Annular Pipe

The effect of drag reducing additive on the structure of turbulence in concentric annular pipe flow was investigated using Particle Image Velocimetry (PIV) technique. Experiments were conducted using a 9m long horizontal flow loop with concentric annular geometry (inner to outer pipe radius ratio = 0.4). The drag reducing additive was a commercially available partially hydrolyzed polyacrylamide (PHPA). The experiments were conducted using 0.1% V/V polymer concentration, giving a drag reduction of 26% at a solvent Reynolds number equal to 56400. Near wall local fluctuating velocity values were determined by analysing the PIV data. The root mean square (RMS) values of radial velocity fluctuations showed a significant decrease with the use of drag reducing additive. The RMS values of axial velocity fluctuations near the wall (Y+<10) were similar for both water and polymer fluid flow; though, higher peaks were obtained during the polymer fluid flow. As compared to water flow, a strong reduction in vorticity was observed during polymer fluid flow. The degree of vorticity reduction on the inner wall was higher than that of the outer wall. Results of the viscous dissipation and the shear production terms in the kinetic energy budget showed that less energy was produced and dissipated by the route of turbulence when using polymer fluid.

scholarly journals Phase-field simulation of core-annular pipe flow

2019 ◽  
Vol 117 ◽  
pp. 14-24 ◽  
Author(s):  
Baofang Song ◽  
Carlos Plana ◽  
Jose M. Lopez ◽  
Marc Avila
Keyword(s):  
Phase Field ◽  
Pipe Flow ◽  
Phase Field Simulation ◽  
Field Simulation ◽  
Annular Pipe

Effect of Prandtl number on the turbulent thermal field in annular pipe flow

2010 ◽  
Vol 37 (8) ◽  
pp. 958-963 ◽  
Author(s):  
M. Ould-Rouiss ◽  
L. Redjem-Saad ◽  
G. Lauriat ◽  
A. Mazouz
Keyword(s):  
Prandtl Number ◽  
Pipe Flow ◽  
Thermal Field ◽  
Annular Pipe

Modeling Gel Fiber Formation in an Emerging Coaxial Flow From a Nozzle

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Harvey Williams ◽  
Michael McPhail ◽  
Sourav Mondal ◽  
Andreas Münch
Keyword(s):  
Pipe Flow ◽  
Fiber Formation ◽  
Cross Linking ◽  
Total Production ◽  
Immiscible Liquids ◽  
Alginate Gel ◽  
Analytical Approximations ◽  
Gel Layer ◽  
Annular Pipe ◽  
Continuous Fabrication

It is important to understand the operational aspects which affect the continuous fabrication of alginate gel fibers. These can be formed from a cross-linking reaction of an alginate precursor injected into a coaxial annular pipe flow with a calcium chloride solution. This is an example of an emerging solid interface that interacts with the flow in its neighborhood. We advance on earlier works by relaxing assumptions of a fixed spatial domain to explore and observe mechanisms controlling gel radius. We use two different models. The first one represents the gel layer as a capillary interface between two immiscible liquids and captures the effect of surface tension. A second model is introduced to treat the cross-linking chemical reaction and its effect on the viscosity as the alginate gel forms. Through numerical simulations and analytical approximations of the downstream behavior, we determine the shape of the fiber in the pipe flow and its impact on the flow velocity as well as on the total production of gel.

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