Couette-Taylor flow

If a fluid is placed between two concentric cylinders, and the inner cylinder rotated, a complex fluid dynamical motion known as Taylor-Couette flow is established. Mass transport is then by exchange between eddy vortices which can, under some conditions, be imagmed as a substantially enlranced diflfiisivity (typically with effective diflfiision coefficients several orders of magnitude above molecular difhision coefficients) that can be altered by varying the rotation rate, and with all species having the same diffusivity. Studies of the BZ and CIMA/CDIMA systems in such a Couette reactor [45] have revealed bifiircation tlirough a complex sequence of front patterns, see figure A3.14.16. 

Vaezi, V., E. S. Oh, and R. C. Aldredge. 1997. High-intensity turbulence measurements in a Taylor-Couette flow reactor. J. Experimental Thermal Fluid Science 15 424-31. 

VFF devices consist of a stationary cyhnder, inside which a concentric cyhn-der rotates. The rotating movement of the inner surface of the annular gap creates a Taylor-Couette flow [16], generating Taylor vortices. The filter medium can... 

Dynamic filtration modules are basically of two types rotating disc filter (RDF) and vortex flow filter (VFF). In the latter, the filtration module has a cylindrical shape and has a rotating concentric cylindrical mesh in its interior. The rotational movement of the internal cylinder generates a Taylor-Couette flow in the annular gap (Roth et al., 1997), creating Taylor vortices that minimize concentration polarization and mesh fouling. Continuous perfusion processes based on this type of filter and operating continuously for up to 100 days have been reported (Mercille et al., 1994). 

M. Avgousti and A.N. Beris, Viscoelastic Taylor-Couette flow bifurcation analysis in the presence of symmetries, Proc. Roy. Soc. London A, 443 (1993) 17-37. 

S.J. Muller, R.G. Larson and E.S.G Shaqfeh, A purely elastic transition in Taylor-Couette flow, Rheol. Acta, 28 (1989) 499-503. 

R.G. Larson, E.S.G. Shaqfeh and S.J. Muller, A purely viscoelastic instability in Taylor-Couette flow, J. Fluid Mech., 218 (1990) 573-600. 

When the Taylor number exceeds a critical value (Tac), a transition from stable Couette flow to vortical Taylor-Couette flow occurs. The critical Taylor number can be calculated by [24] ... 

On-going research is focused on various aspects starting from improving the reactor hydrodynamics to the catalyst development. Several new reactor designs (Fig. 2) with possibilty of scale-up are available (38 0). An improved reactor design is recently published where reactor perfromace is improved by inducing Taylor-Couette flow (41). 

This is based on the friction drag on the large cylindrical surfaces near the boundaries of Taylor-Couette flow. One major advantage of... 

The most promising is the application of the Taylor-vortex column with Taylor-Couette flow. Sorption of hydrophobic organic compounds can lead to under estimation of actual removal efficiency of wastewater treatment, as weU as cross-contamination of the batches of the effluent due to release ofthe sorbed solute molecules. This is supported by the results ofthe laboratory studies, along with the ease ofthe potential scale-up. The critical part in the context ofthe removal of organic compounds from wastewater(s) is the material of the inner cylinder. The surface of the inner cylinder provides a potential sorption surface for hydrophobic organic molecules. Since the PTFE price could be prohibitive for the scale-up, stainless steel, or other materials should be explored as replacements for potential industrial applications. 

Park, Y. (2006). Development and optimization of novel emulsion liquid membranes stabilized by non-Newtonian conversion in Taylor-Couette flow for extraction of selected organic and metallic contaminants. Ph.D. thesis, Georgia Institute of Technology, Atlanta, GA, USA. 

Park, Y., Forney, L. J., Kim, J. H., SkeUand, A. H. P. (2004). Optimum emulsion liquid membranes stabUized by non-Newtonian conversion in Taylor-Couette flow. Chemical Engineering Science 59 5725-5734. 

Wang, L., MARcrasio, D. L., Vigil, R. D. Fox, R. O. 2005a CFD simulation of shear-induced aggregation and breakage in laminar Taylor-Couette flow. Journal of Colloid and Interface Science 282, 380-396. 

A very interesting series of studies of the influence of end effects in the rotating concentric cylinder problem has been published by Mullin and co-workers T. Mullin, Mutations of steady cellular flows in the Taylor experiment,J. Fluid Mech. 121, 207-18 (1982) T. B. Benjamin and T. Mullin, Notes on the multiplicity of flows in the Taylor experiment, J. Fluid Mech. 121, 219-30 (1982) K. A. Cliff and T. Mullin, A numerical and expwerimental study of anomalous modes in the Taylor experiment, J. Fluid Mech. 153, 243-58 (1985) G. Pfister, H. Schmidt, K. A. Cliffe and T. Mullin, Bifurcation phenomena in Taylor-Couette flow in a very short annulus, J. Fluid Mech. 191, 1-18 (1988) K. A. Cliffe, 1.1. Kobine, and T. Mullin, The role of anomalous modes in Taylor-Couette flow, Proc. R. Soc. London Ser. A 439, 341-57 (1992) T. Mullin, Y. Toya, and S. I. Tavener, Symmetry breaking and multiplicity of states in small aspect ratio Taylor-Couette flow, Phys. Fluids 14, 2778-87 (2002). 

Aldredge, R. C., V. Vaezi, and P. D. Ronney. 1998. Premixed-flame propagation in turbulent Taylor-Couette flow. Combustion Flame 115 395. 

O. Liithje, S. Wolff, and G. Pfister Control of chaotic taylor-couette flow with time-delayed feedback, Phys. Rev. Lett. 86, 1745 (2001). 

Baier, G. and Graham, M.D., Two-fluid Taylor-Couette flow with countercurrent axial flow linear theory for immiscible liquids between co-rotating cylinders, Phys. Fluids, 12 (2), 294-303, 2000. 

Fox R. (2008) FLUENT flow lab collaborations -Taylor-Couette flow, http //www.ansys.com/ products/flowlab/collaborations/pdfs/taylor couette flow.pdf. Accessed on January 2008. 

Viscoelastic phenomena may be described through three aspects, namely stress relaxation, creep and recovery. Stress relaxation is the decline in stress with time in response to a constant applied strain, at a constant temperature. Creep is the increase in strain with time in response to a constant applied stress, at a constant temperature. Recovery is the tendency of the material to return partially to its previous state upon removal of an applied load. The material is said to have memory as if it remembers where it came from. Because of the memory effect, in transient flows the behavior of viscoelastic fluids wUl be dramatically different from that of Newtonian fluids. Viseoelastie fluids are fiiU of instabilities. Some examples inelude instabilities in Taylor-Couette flow, in eone-and-plate and plate-and-plate flows (Larson 1992). The extrudate distortion, commonly called melt fraeture, is a notorious example of viscoelastic instability in polymer processing. The viseoelastie instability in injection molding can result in specific surface defects such as tiger stripes (Bogaerds et al. 2004). 

Dr Coney (1971) researched Taylor vortex flow with particular interest in rotary heat exchangers, which he later used in a rotary vapour compression cycle heat pump. Taylor-Couette flows are used in commercial intensified reactors now (see Chapter 5). 

There have recently been rapid advances in our understanding of Taylor-Couette flow between a rotating inner cylinder and a concentric stationary outer cylinder. Hiis progress is reviewed and its implications in the case of eccentric cylinders or journal bearings considered. 

MOBBS, F.R. "Marginal instability in Taylor-Couette flows at very high Taylor nutiber." J. Fluid Mech. 1979, 94,... 

Soos, M, Wang, L, Fox, R O, Sefcik, J and Morbidelli, M (2007), Population balance modeling of aggregation and breakage in turbulent Taylor-Couette flow . Journal of Colloid and Interface Science, 307(2) 433-446. 

---