Abstract
This paper presents an experimental study on the transition from smooth to rough walls, and back to the smooth one, in turbulent closed-conduit flows. These transitions cause a shift on flow velocity profiles that changes their parameters when compared to the flow over a smooth wall. Different water flow rates were imposed in a closed conduit of rectangular cross section, where rough elements consisting of cavities of d- and k-type were positioned covering a part of the bottom wall of the test section. Reynolds numbers based on the channel half-height were moderate, varying between 7800 and 9600, and the regime upstream of the rough elements was hydraulically smooth. Experimental data for this specific case remain scarce and the involved physics rests to be understood. The flow field was measured by low frequency PIV (particle image velocimetry) and by flow visualization, the latter using a continuous 0.1 W laser, a high-speed camera, and scripts written by the authors. From the instantaneous fields measured with PIV, the mean velocities, fluctuations, shear stresses, and turbulence production were computed. The results show the presence of oscillations in Reynolds stress and turbulence production, that are higher for the k-type roughness and were not shown in previous experimental works. From the high-speed movies, the angular velocities and frequencies of vortices in the cavities were computed, and the occurrence of fluid ejection from the cavities to upper layers of the flow was observed. A relation between the angular velocities of inner-cavities vortices and the oscillations in Reynolds stress and turbulence production is proposed.
Similar content being viewed by others
Abbreviations
- B :
-
constant
- d :
-
diameter (m)
- \(d_\mathrm{h}\) :
-
hydraulic diameter (m)
- f :
-
Darcy friction factor
- f :
-
Frequency (Hz)
- h :
-
Channel half height (m)
- H :
-
Channel height (m)
- k :
-
Height of rough elements (m)
- L :
-
Wavelength (m)
- \(l_\mathrm{v}\) :
-
Viscous length (m)
- N :
-
Number of image pairs
- P :
-
Turbulence production term (m\(^2\)/s\(^3\))
- Q :
-
Volumetric flow rate (m\(^3\)/h)
- Re :
-
Reynolds number based on the boundary-layer thickness
- \(Re_{\mathrm{dh}}\) :
-
Reynolds number based on the hydraulic diameter
- t :
-
Time (s)
- u :
-
Longitudinal component of the velocity (m/s)
- \(u_*\) :
-
Shear velocity (m/s)
- v :
-
Vertical component of the velocity (m/s)
- \(v_\mathrm{t}\) :
-
Tangential velocity (m/s)
- w :
-
Distance between rough elements (m)
- x :
-
Horizontal coordinate (m)
- y :
-
Vertical coordinate (m)
- \(\delta\) :
-
Boundary-layer thickness (m)
- \(\Delta\) :
-
Displacement
- \(\kappa\) :
-
von Kármán constant
- \(\lambda\) :
-
Ratio between the projected frontal and parallel areas
- \(\mu\) :
-
Dynamic viscosity (Pa s)
- \(\nu\) :
-
Kinematic viscosity (m\(^2\)/s)
- \(\Omega\) :
-
Angular velocity (rad/s)
- \(\rho\) :
-
Specific mass (kg/m\(^3\))
- \(\tau\) :
-
Shear stress (N/m\(^2\))
- 0:
-
Relative to the smooth surface
- 0:
-
Relative to the origin of the vertical coordinate
- \(\mathrm{bla}\) :
-
Relative to Blasius correlation
- \(\mathrm{d}\) :
-
Relative to the displaced coordinate system
- \(\mathrm{dh}\) :
-
Relative to the hydraulic diameter
- \(\mathrm{s}\) :
-
Sand equivalent
- \(\mathrm{v}\) :
-
Relative to the viscous layer
- \(+\) :
-
Normalized by the viscous length \(l_\mathrm{v}\) or by the shear velocity \(u_*\)
- \(\overline{\quad }\) :
-
Averaged in time
- \('\) :
-
Fluctuation
References
Choi KS, Fujisawa N (1993) Possibility of drag reduction using d-type roughness. Appl Sci Res 50(3):315–324
Suzuki Y, Kasagi N (1994) Turbulent drag reduction mechanism above a riblet surface. AIAA J 32(9):1781–1790
Dizaji HS, Jafarmadar S, Mobadersani F (2015) Experimental studies on heat transfer and pressure drop characteristics for new arrangements of corrugated tubes in a double pipe heat exchanger. Int J Therm Sci 96(Supplement C):211–220
Hagen G (1854) Über den einfluss der temperatur auf die bewegung des wassers in röhen. Math Abh Akad Wiss 3:17–98
Darcy H (1857) Recherches expérimentales relatives au mouvement de l’eau dans les tuyaux. Mallet-Bachelier, Paris
Nikuradse J (1933) Laws of flow in rough pipes. VDI Forschungsheft, In translation. NACA TM 1292:361
Schlichting H (1936) Experimental investigation of the problem of surface roughness. Ing Arch, In translation. NACA TM 823 7:1–34
Jiménez J (2004) Turbulent flows over rough walls. Ann Rev Fluid Mech 36:173–196
Perry A, Schofield W, Joubert P (1969) Rough wall turbulent boundary layers. J Fluid Mech 37(2):383–413
Clauser FH (1954) Turbulent boundary layers in adverse pressure gradient. J Aeronaut Sci 21:91–108
Clauser FH (1956) Turbulent boundary layer. Adv Appl Mech 4:1–51
Coleman HW, Hodge BK, Taylor RP (1984) A re-evaluation of Schlichtings surface roughness experiment. J Fluids Eng 106(1):60–65
Raupach MR, Antonia RA, Rajagopalan S (1991) Rough-wall boundary layers. Appl Mech Rev 44:1–25
Djenidi L, Anselmet F, Antonia RA (1994) LDA measurements in a turbulent boundary layer over a d-type rough wall. Exp Fluids 16:323–329
Djenidi L, Elavarasan R, Antonia RA (1999) The turbulent boundary layer over transverse square cavities. J Fluid Mech 395:271–294
Sutardi, Ching CY (2003) The response of a turbulent boundary layer to different shaped transverse grooves. Exp Fluids 35(4):325–337
Leonardi S, Orlandi P, Djenidi L, Antonia RA (2004) Structure of turbulent channel flow with square bars on one wall. Int J Heat Fluid Flow 25:384–392
Leonardi S, Orlandi P, Antonia RA (2007) Properties of d- and k-type roughness in a turbulent channel flow. Phys Fluids 19(12):125101
Schultz MP, Flack KA (2007) The rough-wall turbulent boundary layer from the hydraulically smooth to the fully rough regime. J Fluid Mech 580:381–405
Lee JH (2015) Turbulent boundary layer flow with a step change from smooth to rough surface. Int J Heat Fluid Flow 54:39–54
Lee J, Kim JH, Lee JH (2016) Scale growth of structures in a turbulent boundary layer with a rod-roughened wall. Phys Fluids 28:015104
Castro IP (2007) Rough-wall boundary layers: mean flow universality. J Fluid Mech 585:469485
De Marchis M, Milici B, Napoli E (2015) Numerical observations of turbulence structure modification in channel flow over 2d and 3d rough walls. Int J Heat Fluid Flow 56(Supplement C):108–123
Schlichting H (2000) Boundary-layer theory. Springer, New York
Acknowledgements
The authors are grateful to ANP, Repsol, Cepetro, Labpetro, CNPq (Grant no. 400284/2016-2), and to FAPESP (Grants nos. 2012/19562-6 and 2016/13474-9) for the provided financial support.
Author information
Authors and Affiliations
Corresponding author
Additional information
Technical Editor: Jader Barbosa Jr.
Rights and permissions
About this article
Cite this article
Maltese Meletti de Oliveira, G., de Moraes Franklin, E. Transitions between smooth and rough surfaces in turbulent channel flows for d- and k-type rough elements. J Braz. Soc. Mech. Sci. Eng. 40, 187 (2018). https://doi.org/10.1007/s40430-018-1113-9
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/s40430-018-1113-9