Abstract
In a recent paper we have investigated mixing and heat transfer enhancement in a mixer composed of two circular rods maintained vertically in a cylindrical tank. The rods and tank can rotate around their revolution axes while their surfaces were maintained at a constant temperature. In the present study we investigate the differences in the thermal mixing process arising from the utilization of a constant heat flux as a boundary condition. The study concerns a highly viscous fluid with a high Prandtl number for which this chaotic mixer is suitable. By solving numerically the flow and energy equations, and using different statistical tools we characterize the evolution of the fluid temperature and its homogenization. Fundamental differences are reported between these two modes of heating or cooling: while the mixing with an imposed temperature results in a homogeneous temperature field, with a fixed heat flux we observe a constant difference between the maximal and minimal temperatures that establish in the fluid; the extent of this difference is governed by the efficiency of the mixing protocol.
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Abbreviations
- A :
-
Area (m2)
- C p :
-
Heat capacity (J/kg K)
- k :
-
Thermal conductivity (W/m K)
- L :
-
Wall characteristic length (m)
- p :
-
Pressure (Pa)
- \(\dot q\) :
-
Surface heat flux (W/m2)
- R 3 :
-
Tank radius (m)
- R 1, R 2 :
-
Rod radii (m)
- t :
-
Time (s)
- T :
-
Temperature (K)
- U :
-
Maximum tangential velocity of the walls (m/s)
- \({\bf U}\) :
-
Velocity field (m/s)
- Nu :
-
Nusselt number
- Pe :
-
Péclet number
- Pr :
-
Prandtl number
- Re :
-
Reynolds number
- X :
-
Rescaled dimensionless temperature
- \(\varepsilon\) :
-
Eccentricity (m)
- ρ:
-
Fluid density (kg/m3)
- σ:
-
Standard deviation
- τ:
-
Period of modulation (s)
- \(\overset{=}{\tau}\) :
-
Viscous stress tensor (Pa)
- \(\Upomega\) :
-
Angular velocity (rad/s)
- c :
-
Cell
- m :
-
Mean
- f :
-
Face of a cell
References
Ottino JM (1989) The kinematics of mixing: stretching, chaos, and transport. Cambridge University Press, Cambridge
Aref H (2002) The development of chaotic advection. Phys Fluids 14:1315–1325
Jana SC, Sau M (2004) Effects of viscosity ratio and composition on development of morphology in chaotic mixing of polymers. Polymer 45(5):1665–1678
Metcalfe G, Lester DR (2009) Mixing and heat transfer of highly viscous food products with a continuous chaotic duct flow. J Food Eng 95(1):21–29
Caubet S, Le Guer Y, Grassl B, El Omari K, Normandin E (2011) A low-energy emulsification batch mixer for concentrated oil-in-water emulsions. AIChE J 57(1):27–39
Chang HC, Sen M (1994) Application of chaotic advection to heat transfer. Chaos Solitons Fractals 4(6):955–976
Acharya N, Sen M, Chang HC (2001) Analysis of heat transfer enhancement in coiled-tube heat exchangers. Int J Heat Mass Transf 44(17):3189–3199
Peerhossaini H, Castelain C, Le Guer Y (1993) Heat exchanger design based on chaotic advection. Exp Therm Fluid Sci 7(4):333–344
Mokrani A, Castelain C, Peerhossaini H (1997) The effects of chaotic advection on heat transfer. Int J Heat Mass Transf 40(13):3089–3104
Gouillart E, Dauchot O, Dubrulle B, Roux S, Thiffeault JL (2008) Slow decay of concentration variance due to no-slip walls in chaotic mixing. Phys Rev E 78(2):026211
Gouillart E, Thiffeault JL, Dauchot O (2010) Rotation shields chaotic mixing regions from no-slip walls. Phys Rev Lett 104:204502
El Omari K, Le Guer Y (2010) Alternate rotating walls for thermal chaotic mixing. Int J Heat Mass Transf 53:123–134
Ghosh S, Chang HC, Sen M (1992) Heat-transfer enhancement due to slender recirculation and chaotic transport between counter-rotating eccentric cylinders. J Fluid Mech 238:119–154
Ganesan V, Bryden MD, H Brenner (1997) Chaotic heat transfer enhancement in rotating eccentric annular-flow systems. Phys Fluids 9:1296–1306
Lefevre A, Mota JPB, Rodrigo AJS, Saatdjian E (2003) Chaotic advection and heat transfer enhancement in Stokes flows. Int J Heat Fluid Flow 24(3):310–321
Mota JPB, Rodrigo AJS, Saatdjian E (2007) Optimization of heat-transfer rate into time-periodic two-dimensional Stokes flows. Int J Numer Methods Fluids 53(6):915–931
Price TJ, Mullin T, Kobine JJ (2003) Numerical and experimental characterization of a family of two-roll-mill flows. R Soc Lond Proc Ser A 459:117–135
Young DL, Chiu CL, Fan CM (2007) A hybrid Cartesian/immersed-boundary finite-element method for simulating heat and flow patterns in a two-roll mill. Numer Heat Transf Part B Fundam 51(3–4):251–274
Chiu CL, Fan CM, Young DL (2009) 3D hybrid Cartesian/immersed-boundary finite-element analysis of heat and flow patterns in a two-roll mill. Int J Heat Mass Transf 52(7–8):1677–1689
Jana SC, Metcalfe G, Ottino JM (1994) Experimental and computational studies of mixing in complex Stokes flows: the vortex mixing flow and multicellular cavity flows. J Fluid Mech 269:199–246
El Omari K, Le Guer Y (2009) A numerical study of thermal chaotic mixing in a two rod rotating mixer. Comput Therm Sci 1:55–73
El Omari K, Le Guer Y (2010) Thermal chaotic mixing of power law fluids in a mixer with alternately-rotating walls. J Non-Newton Fluid Mech 165:641–651
Le Guer Y, El Omari K (2012) Chaotic advection for thermal mixing. In: Aref H, van der Giessen E (eds) Advances in applied mechanics, vol 45. Elsevier, Amsterdam, pp 189–237
Geuzaine C, Remacle JF (2009) Gmsh: a three-dimensional finite element mesh generator with built-in pre-and post-processing facilities. Int J Numer Methods Eng 79(11):1309–1331
El Omari K, Kousksou T, Le Guer Y (2011) Impact of shape of container on natural convection and melting inside enclosures used for passive cooling of electronic devices. Appl Therm Eng 31:3022–3035
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El Omari, K., Le Guer, Y. Laminar mixing and heat transfer for constant heat flux boundary condition. Heat Mass Transfer 48, 1285–1296 (2012). https://doi.org/10.1007/s00231-012-0976-z
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DOI: https://doi.org/10.1007/s00231-012-0976-z