Abstract
Different data analysis techniques for characterisation of the turbulent flow past a surface-mounted rib are reviewed. Deficiencies of the existing techniques are explained and modified techniques for determination of coherent structure magnitude and phase jitter are suggested. The effect of fundamental excitation on the flow is studied by using these turbulent signal analysis techniques. The appropriate length scale for characterizing the large-scale structures present in the reattaching shear layer of the surface-mounted rib is found to be the momentum thickness at the downstream edge of the rib, and the corresponding Strouhal number is 0.013. This is in contrast to a rib in the free stream, where the rib height is the correct scaling parameter. The post reattachment region is observed to be dominated by large-scale structures contrary to the traditional belief that large eddies break into small scales at the reattachment location. Low magnitude of phase jitter in the near field region is observed, indicating coherence of the flow structures. Phase decorrelation begins to occur beyond three rib heights from the downstream edge of the rib. From the quadrant analysis results, the outer edge of the shear layer is observed to be dominated by large-scale ejection motions.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Arnal M P, Goering D J, Humphrey J A C 1991 Vortex shedding from a bluff body adjacent to a plane sliding wall.J. Fluid Eng. 113: 384–398
Fiedler H E, Mensing P 1985 The plane turbulent shear layer with periodic excitation.J. Fluid Mech. 150: 281–309
Hasan M A Z 1992 The flow over a backward facing step under controlled perturbation: Laminar separation.J. Fluid Mech. 238: 73–96
Hinze J O 1975Turbulence (New York: McGraw Hill)
Ho C M, Huere P 1984 Perturbed free shear layers.Annu. Rev. Fluid Mech. 16: 365–424
Ho C M, Zohar Y, Foss J K, Buell J C 1991 Phase decorrelation of coherent structures in a free shear layer.J. Fluid Mech. 230: 319–337
Huerre P, Monkewitz P A 1985 Absolute and convective instabilities in free shear layers.J. Fluid Mech. 159: 151–168
Hussain A K M F 1986 Coherent structures and turbulence.J. Fluid Mech. 173: 303–356
Hussain A K M F, Zaman K B M Q 1980 Vortex pairing in a circular jet under controlled excitation,J. Fluid Mech. 101: 493–544
Mcmanus K R, Vandsburger U, Bowman C T 1990 Combustor performance enhancement through direct shear layer excitation.Combust. Flame 82: 75–92
Najjar F M, Vanka S P 1993 Numerical study of a separated-reattaching flow.Theor. Comput. Fluid Dyn. 5: 291–308
Panigrahi P K, Acharya S 1996 Spectral characteristics of separated flow behind a surface-mounted square rib.27th AIAA Fluid Dynamics Conference, AIAA 96–1931
Panigrahi P K, Acharya S 1999 Mechanisms of turbulence transport in a turbine blade coolant passage with a rib turbulator.J. Turbomachinery 121: 152–159
Rajaee M, Karlsson S K F 1992 On the Fourier space decomposition of free shear flow measurements and mode generation in the pairing process.Phys. Fluids A4: 321–339
Tarn C K W 1978 Excitation of instability waves in a two-dimensional shear layer by sound.J. Fluid Mech. 89: 357–371
Wallace J M, Eckelmann H, Brodkey R S 1972 The wall region in turbulent shear flow.J. Fluid Mech. 54: 39–48
Willmarth W W, Lu S S 1972 Structure of the Reynolds stress near the wall.J. Fluid Mech. 55: 65–92
Yang Z, Karlsson S K F 1991 Evolution of coherent structures in a plane shear layer.Phys. Fluids A3: 2207–2219
Zhou M D, Heine C, Wygnanski I 1996 The effects of excitation on the coherent and random motion in a plane wall jet.J. Fluid Mech. 310: 1–37
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Panigrahi, P.K. Fundamentally excited flow past a surface-mounted rib. Part I: Turbulent structure characterisation. Sadhana 26, 387–412 (2001). https://doi.org/10.1007/BF02703439
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF02703439