Abstract
Particle image velocimetry experiments have been carried out to obtain visualizations and measurements of the main and secondary flow fields in a square channel with a sharp “U” turn. Both the main and the secondary flow fields have been used to perform a 3D reconstruction of the mean flow and vortical fields in the turn region and in the outlet duct. In order to study the influence of the rotation, tests both in stationary (absence of rotation, Re = 20,000) and in rotating (Re = 20,000 and Ro = 0.3) conditions have been performed. The results show that the Coriolis and centrifugal forces, caused by the rotation, yield strong modifications to the symmetrical flow and vortical fields that are generated, in the static case, only by the abrupt inversion of the flow direction.
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Notes
 1.
The λ _{2}criterion is a vortex identification method based on the eigenvalues of the sum of the strain and rotation square tensor.
Abbreviations
 3D:

Threedimensional
 CCD:

Chargecoupled device
 LASER:

Light amplification by stimulated emission of radiation
 LDA:

Laser doppler anemometry
 Nd:YAG:

Neodymium yttrium aluminium garnet
 PIV:

Particle image velocimetry
 C :

Circuit used to the evaluation of the vorticity components
 D :

Channel hydraulic diameter
 \( \underline{l} \) :

Direction normal to the planar surface S
 Re :

Reynolds number
 Ro :

Rotation number
 S :

Planar surface bounded by the circuit C
 U :

Fluid mean velocity
 u, v, w:

Mean velocity components
 u′, v′:

Turbulence intensity
 u*:

Wall friction velocity
 u_{1}, w_{1}:

Mean velocity components obtained from the images acquired with the rotating channel (Re = 20,000, Ro = 0.3)
 u_{2}, w_{2}:

Mean velocity components obtained from the images acquired with the rotating channel and the fluid at rest
 U_{2}, W_{2}:

Velocity components of V _{pp}
 u_{g}, v_{g}, w_{g}:

Mean velocity components relative to the 3D grids
 \( \underline{V} \) :

Local velocity vector
 V :

Local velocity module
 V _{pp} :

Rotation peripheral velocity relative to the generic point of the investigated plane
 W _{2m} :

Spatial average of the mean (in time) velocity component w _{2} distribution obtained from the images acquired with the rotating channel and with the fluid at rest
 x, y, z:

Cartesian spatial coordinates
 x_{c}, z_{c}:

Cartesian spatial coordinates of the channel rotation centre
 α :

Rotation angle
 λ _{2} :

Second eigenvalue of the sum of the strain and rotation square tensor
 μ :

Dynamic viscosity coefficient of the fluid
 ρ :

Mass density of the fluid
 ω :

Channel rotational speed
 Ω:

Local vorticity module
 Ω_{l} :

Vorticity components relative to the l direction
 Ω_{ x }, Ω_{ y }, Ω_{ z } :

Mean vorticity components
References
AlQahtani M, Jang YJ, Chen HC, Han JC (2002) Flow and heat transfer in rotating twopass rectangular channels (AR = 2) by Reynolds stress turbulence model. Int J Heat Mass Transf 45:1823–1838
Arts T, Lambert de Rouvroit M, Rau G, Acton P (1992) Aerothermal investigation of the flow developing in a 180 degree turn channel. Proceedings of international symposium on heat transfer in turbomachinery, Athens
Astarita T, Cardone G (2005) Analysis of interpolation schemes for image deformation methods in PIV. Exp Fluids 38:233–243
Brossard C, Servouze Y, Gicquel P, Barrier R (2005) Characterization of the flow field inside a rotating, ribroughened, Ushaped channel using particle image velocimetry. In: Proceedings of 21st international congress instrumentation in aerospace simulation facilities
Cheah SC, Iacovides H, Jackson DC, Ji H, Launder BE (1996) LDA investigation of the flow development through rotating Uducts. J Turbomach 118:590–596
Foucaut JM, Stanislas M (2002) Some considerations on the accuracy and frequency response of some derivative filters applied to particle image velocimetry vector fields. Meas Sci Technol 13:1058–1071
Iacovides H, Raisee M (1999) Recent progress in the computation of flow and heat transfer in internal cooling passages of turbine blades. Int J Heat Fluid Flow 20:320–328
Iacovides H, Launder BE, Li HY (1996) The computation of the flow development through stationary and rotating Uducts of strong curvature. Int J Heat Fluid Flow 17:22–33
Iacovides H, Jackson DC, Kelemenis G, Launder BE, Yuan YM (1999) Experiments on local heat transfer in a rotating squareended Ubend. Int J Heat Fluid Flow 20:302–310
Jeong J, Hussain F (1995) On the identification of a vortex. J Fluid Mech 285:69–94
Kim KM, Kim YY, Lee DH, Rhee DH, Cho HH (2007) Influence of duct aspect ratio on heat/mass transfer in coolant passages with rotation. Int J Heat Fluid Flow 28:357–373
Kiml R, Mochizuki S, Murata A (1998) Influence of 180 degree sharp turn on the heat transfer and flow behavior in a smooth square cross sectional serpentine channel. In: Proceedings of 8th international symposium on flow visualizations
Kline SC, McClintok FA (1953) Describing uncertainties in singlesample experiment. Mech Eng 75:3–8
Liou TM, Chen C–C (1999a) LDV study of the developing flows through a smooth duct with a 180 deg straightcorner turn. J Turbomach 121:167–174
Liou TM, Chen C–C (1999b) Heat transfer in a rotating twopass smooth passage with a 180° rectangular turn. Int J Heat Mass Transf 42:231–247
Murata A, Mochizuki S (2004) Large eddy simulation of turbulent heat transfer in a rotating twopass smooth square channel with sharp 180° turns. Int J Heat Mass Transf 47:683–698
Qin Z, Pletcher RH (2006) Large eddy simulation of turbulent heat transfer in a rotating square duct. Int J Heat Fluid Flow 27:371–390
Schabacker J, Bolcs A, Johnson BV (1998) PIV investigation of the flow characteristics in an internal coolant passage with two ducts connected by a sharp 180° bend. ASME Preprint 98GT544, Stockholm, Sweden
Son SY, Kihm KD, Han JC (2002) PIV flow measurements for heat transfer characterization in twopass square channels with smooth and 90° ribbed walls. Int J Heat Mass Transf 45:4809–4822
Su G, Chen HC, Han JC, Heidmann JD (2004) Computation of flow and heat transfer in rotating channels (AR = 1:1, 1:2, and 1:4) with smooth walls by a Reynolds stress turbulence model. Int J Heat Mass Transf 47:5665–5683
Wang TS, Chyu MK (1992) Influence of turning geometry on convective transport in a square duct with a 180–deg sharp turn. Proceedings of international symposium on heat transfer in turbomachinery, Athens
Acknowledgments
The authors wish to thank Prof. Giovanni Maria Carlomagno for helpful discussion throughout the course of this work.
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Gallo, M., Astarita, T. 3D reconstruction of the flow and vortical field in a rotating sharp “U” turn channel. Exp Fluids 48, 967–982 (2010) doi:10.1007/s0034800907765
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Keywords
 Vortex
 Particle Image Velocimetry
 Vortical Structure
 Vortical Field
 External Wall