Abstract
We present the results of flow visualization and velocity measurements on a hexagonal structured surface. Several configurations with concave and convex hexagonal structures are investigated. Each hexagonal structure is 2.7 mm deep and 33 mm wide (width between flats) and has a height to diameter ratio of 0.05 based on equivalent diameter. Considered are flow velocities 19 m/s, 24 m/s, and 27 m/s. The flow bifurcates on the leading edge of the concave configuration into two counter rotating vortices and propagates further in streamwise direction. The circulating regions are identified by the peaks in r.m.s. velocity curves. In case of concave configuration, the flow splits up into counter rotating vortical structures in a vertical plane parallel to the flow. The lower vortex rotating in the opposite direction of the flow cause the oil film fringes to drift upstream. Complex circulating regions similar to the arrangement of slices in an orange can be observed on the trailing edge of the concave hexagonal structure.
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U. Butt, L. Jehring, and C. Egbers, Mechanism of drag reduction for circular cylinders with patterned surface, Int. J. Heat and Fluid Flow, 2014, Vol. 45, P. 128–134.
P.R. Gromov, A.B. Zobnin, M.I. Rabinovich, and M.M. Sushchik, Creation of solitary vortices in a flow around shallow spherical depressions, Sov. Tech. Phys. Lett., 1986, Vol. 12, No. 11, P. 1323–1328.
T. Kimura and M. Tsutahara, Fluid dynamic effects of grooves on circular cylinder surface, AIAA J., 1991, Vol. 29, No. 12, P. 2062–2068.
P.W. Bearman and J.K. Harvey, Control of circular cylinder flow by the use of dimples, AIAA J., 1993, Vol. 31, No. 10, P. 1753–1756.
J. Choi, W. Jeon, and H. Choi, Mechanism of drag reduction by dimples on a sphere, Phys. Fluids, 2006, Vol. 18, No. 4, P. 041702-1−041702-4.
V.I. Terekhov, S.V. Kalinina, and Y.M. Mshvidobadze, Flow structure and heat transfer on a surface with a unit hole depression, Russ. J. Engng Thermophys., 1995, Vol. 5, No. 1, P. 11–34.
V.D. Zhak, The Taylor–Goertler vortices and three-dimensional flow evolution in cavity, Russ. J. Engng Thermophys., 1995, Vol. 5, No. 2, P. 165–176.
A.V. Shchukin, A.P. Kozlov, Ya.P. Chudnovskii, and R.S. Agachev, Intensification of heat exchange by spherical depressions. A survey, Appl. Energy: Rus. J. of Fuel, Power, and Heat Systems, 1998, Vol. 36, No. 3, P. 45–62.
L.H. Tanner and L.G. Blows, A study of the motion of oil films on the surfaces in air flow, with application to the measurement of skin friction, J. Physics E: Scientific Instruments, 1976, Vol. 9, P. 194–202.
H.C.H. Ng, I. Marusic, J.P. Monty, N. Hutchins, and M.S. Chong, Oil film interferometry in high Reynolds number turbulent boundary layers, in: 16th Australasian Fluid Mechanics Conference Crown Plaza, Gold Coast, Australia, 2–7 December 2007, P. 807–814.
G. Pailhas, P. Barricau, Y. Touvet, and L. Perret, Friction measurement in zero and adverse pressure gradient boundary layer using oil droplet interferometric method, Experiments in Fluids, 2009, Vol. 47, P. 195–207.
P.M. Ligrani, J.L. Harrison, G.I. Mahmmod, and M.L. Hill, Flow structure due to dimple depressions on a channel surface, Phys. Fluids, 2001, Vol. 13, No. 11, P. 3442–3451.
U. Butt, Experimental investigation of the flow over macroscopic hexagonal structured surfaces, BTU Cottbus, 2013, urn:nbn:de:kobv:co1-opus4-30555.
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Butt, U., Egbers, C. Flow structure due to hexagonal cavities and bumps on a plate surface. Thermophys. Aeromech. 23, 839–847 (2016). https://doi.org/10.1134/S0869864316060068
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DOI: https://doi.org/10.1134/S0869864316060068