Experimental and numerical studies of flow field and mass transfer phenomena on sinusoidal wavy walls
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SHORT COMMUNICATION
Experimental and numerical studies of flow field and mass transfer phenomena on sinusoidal wavy walls T. Yamagata 1
&
N. Fujisawa 1,2
Received: 9 June 2020 / Accepted: 22 September 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The flow field and mass transfer phenomena on wavy walls are studied both experimentally and numerically for application to the pipe-wall thinning of nuclear power plant. The numerical simulations are carried out using four turbulence models and the results are compared with the velocity field on wavy planar wall measured by particle image velocimetry, and the mass transfer coefficient data on a pipe wall in literature. The near-wall velocity field of the wavy wall shows the flow separation and reattachment, and the high intensity turbulence energy generation over the recirculation region along the trough. The predictions by AKN model indicate better agreement with the experimental behavior of mean flow and turbulence characteristics on the wavy wall, while the other models fail to predict the reattachment behavior. Further attention is focused on the mass transfer enhancement behavior over the wavy pipe wall. It increases with an increased relative roughness associated with the growth of recirculation region and the increased turbulence energy. However, the growth of mass transfer coefficient saturates at large relative roughness because of the limitation of the recirculation region and the downstream shift of high turbulence energy region over the trough. The mass transfer behaviors on the wavy pipe wall are better predicted by the k-ω shear stress transport model. Keywords Sinusoidal wavy wall . Turbulence model . PIV . Velocity field . Mass transfer . FAC
Nomenclature Cb concentration in bulk flow. Cw saturated concentration on wall. c concentration. D diffusion coefficient. d pipe diameter. h height of wavy wall from centerline. Jw diffusive mass flux. K mass transfer coefficient. K0 mass transfer coefficient in straight pipe flow. Kx, Ky axial and normal mass transfer coefficient, respectively. K x; K y average value of Kx, Ky, respectively. k turbulence energy.
* T. Yamagata [email protected] 1
Faculty of Engineering, Niigata University, 8050 Ikarashi 2, Nishi, Niigata 950-2181, Japan
2
Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
Re Reλ Sc U0 Uf Ux Uτ u,v,w x,y,z xs xr x’, y’ y+
Reynolds number (=U0d/ν). Reynolds number (=Ufλ/ν). Schmidt number (= ν/D). bulk velocity. free-stream velocity. streamwise mean velocity. friction velocity. velocity components. coordinates. separation point. reattachment point. coordinates on rough wall. dimensionless wall distance (=y’Uτ/ν).
Greek letters ε turbulent dissipation rate. λ wavelength of wavy wall. μ viscosity of fluid. ν kinematic viscosity of fluid. ρ density of fluid.
Heat Mass Transfer
1 Introduction The flow accelerated corrosion (FAC) is the dissolution phenomenon of the iron ions in the carbon steel pipe-wall into the bulk f
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