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

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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Heat Transfer in Turbulent Pipe Flow for Liquids Having a Temperature-Dependent Viscosity

Journal of Heat Transfer ◽

10.1115/1.3450785 ◽

1978 ◽

Vol 100 (2) ◽

pp. 224-229 ◽

Cited By ~ 2

Author(s):

O. T. Hanna ◽

O. C. Sandall

Keyword(s):

Heat Transfer ◽

Friction Factor ◽

Pipe Flow ◽

Turbulent Pipe Flow ◽

Fluid Viscosity ◽

Temperature Dependent ◽

Temperature Dependent Viscosity ◽

Analytical Approximations ◽

Constant Viscosity ◽

Dependent Viscosity

Analytical approximations are developed to predict the effect of a temperature-dependent viscosity on convective heat transfer through liquids in fully developed turbulent pipe flow. The analysis expresses the heat transfer coefficient ratio for variable to constant viscosity in terms of the friction factor ratio for variable to constant viscosity, Tw, Tb, and a fluid viscosity-temperature parameter β. The results are independent of any particular eddy diffusivity distribution. The formulas developed here represent an analytical approximation to the model developed by Goldmann. These approximations are in good agreement with numerical solutions of the model nonlinear differential equation. To compare the results of these calculations with experimental data, a knowledge of the effect of variable viscosity on the friction factor is required. When available correlations for the friction factor are used, the results given here are seen to agree well with experimental heat transfer coefficients over a considerable range of μw/μb.

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A liquid plug moving in an annular pipe—Flow analysis

Physics of Fluids ◽

10.1063/1.5050258 ◽

2018 ◽

Vol 30 (9) ◽

pp. 093605 ◽

Cited By ~ 2

Author(s):

Yadi Cao ◽

Ri Li

Keyword(s):

Pipe Flow ◽

Flow Analysis ◽

Liquid Plug ◽

Annular Pipe

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

International Journal of Heat and Fluid Flow ◽

10.1016/j.ijheatfluidflow.2020.108725 ◽

2020 ◽

Vol 86 ◽

pp. 108725

Author(s):

Edris Bagheri ◽

Bing-Chen Wang

Keyword(s):

Pipe Flow ◽

Radius Ratio ◽

Annular Pipe

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The Development of Swirling Decaying Laminar Flow in an Annular Pipe

E3S Web of Conferences ◽

10.1051/e3sconf/20185103001 ◽

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.

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Patterns in Wall-Bounded Shear Flows

Annual Review of Fluid Mechanics ◽

10.1146/annurev-fluid-010719-060221 ◽

2020 ◽

Vol 52 (1) ◽

pp. 343-367 ◽

Cited By ~ 19

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.

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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

Volume 7B: Fluids Engineering Systems and Technologies ◽

10.1115/imece2013-64663 ◽

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.

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Monocyte Adhesion and Spreading on Human Endothelial Cells Is Dependent on Rho-regulated Receptor Clustering

The Journal of Cell Biology ◽

10.1083/jcb.145.6.1293 ◽

1999 ◽

Vol 145 (6) ◽

pp. 1293-1307 ◽

Cited By ~ 201

Author(s):

Beata Wójciak-Stothard ◽

Lynn Williams ◽

Anne J. Ridley

Keyword(s):

Endothelial Cells ◽

Stress Fiber ◽

Cytochalasin D ◽

Fiber Formation ◽

Dominant Negative ◽

Cross Linking ◽

Monocyte Adhesion ◽

Human Endothelial Cells ◽

Receptor Clustering ◽

Fiber Assembly

The GTPase Rho is known to mediate the assembly of integrin-containing focal adhesions and actin stress fibers. Here, we investigate the role of Rho in regulating the distribution of the monocyte-binding receptors E-selectin, ICAM-1, and VCAM-1 in human endothelial cells. Inhibition of Rho activity with C3 transferase or N19RhoA, a dominant negative RhoA mutant, reduced the adhesion of monocytes to activated endothelial cells and inhibited their spreading. Similar effects were observed after pretreatment of endothelial cells with cytochalasin D. In contrast, dominant negative Rac and Cdc42 proteins did not affect monocyte adhesion or spreading. C3 transferase and cytochalasin D did not alter the expression levels of monocyte-binding receptors on endothelial cells, but did inhibit clustering of E-selectin, ICAM-1, and VCAM-1 on the cell surface induced by monocyte adhesion or cross-linking antibodies. Similarly, N19RhoA inhibited receptor clustering. Monocyte adhesion and receptor cross-linking induced stress fiber assembly, and inhibitors of myosin light chain kinase prevented this response but did not affect receptor clustering. Finally, receptor clusters colocalized with ezrin/moesin/ radixin proteins. These results suggest that Rho is required in endothelial cells for the assembly of stable adhesions with monocytes via the clustering of monocyte-binding receptors and their association with the actin cytoskeleton, independent of stress fiber formation.

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