Hostname: page-component-5d59c44645-mhl4m Total loading time: 0 Render date: 2024-03-03T07:11:14.964Z Has data issue: false hasContentIssue false

Experimental analysis of the effect of local base blowing on three-dimensional wake modes

Published online by Cambridge University Press:  28 November 2019

M. Lorite-Díez
Departamento de Ingeniería Mecánica y Minera, Universidad de Jaén, Campus de las Lagunillas, 23071Jaén, Spain
J. I. Jiménez-González*
Departamento de Ingeniería Mecánica y Minera, Universidad de Jaén, Campus de las Lagunillas, 23071Jaén, Spain
L. Pastur
Institute of Mechanical Sciences and Industrial Applications, ENSTA Paris, Institut Polytechnique de Paris, 828 Bd des Maréchaux, F-91762Palaiseau CEDEX, France
C. Martínez-Bazán
Departamento de Ingeniería Mecánica y Minera, Universidad de Jaén, Campus de las Lagunillas, 23071Jaén, Spain
O. Cadot
School of Engineering, University of Liverpool, LiverpoolL69 3GH, UK
Email address for correspondence:


Wake modes of a three-dimensional blunt-based body near a wall are investigated at a Reynolds number $Re=10^{5}$. The targeted modes are the static symmetry-breaking mode and two antisymmetric periodic modes. The static mode orientation is aligned with the horizontal major $y$-axis of the base and randomly switches between a positive $P$ and a negative $N$ state leading to long-time bistable dynamics of the turbulent wake. The modifications of these modes are studied when continuous blowing is applied at different locations through four slits along the base edges (denoted L for left, R for right, T for top and B for bottom) in either four single asymmetric configurations or two double symmetric configurations (denoted LR and TB). Two regimes, referred to as mass and momentum, are clearly identifiable for all configurations. The mass regime, which is fairly insensitive to blowing momentum and location, is characterized by the growth of the recirculating bubble as the total injected flow rate is increased, and is associated with a base drag reduction and interpreted as resulting from the equilibrium between mass fluxes feeding and emptying the recirculating region. A simple budget model is shown to be in agreement with entrainment velocities measured for isolated turbulent mixing layers. The strength of the static mode is reduced up to 20 % when the bubble length is maximum, whereas no change in the periodic mode frequencies is found. On the other hand, the momentum regime is characterized by the deflating of the recirculating bubble, leading to base drag increase, and it is interpreted by the free shear layer forcing, which increases the entrainment velocity, thus emptying the recirculating bubble. In this regime the static mode orientation is imposed by the blowing symmetry. Lateral L and R (respectively top/bottom T and B) blowing configurations select $P$ or $N$ states in the horizontal (respectively vertical) direction, while bistable dynamics persists for the symmetric LR and TB configurations. The shape of periodic modes follows the changes in wake static orientation. The transition between the two regimes is governed by both the total injected flow rate and the location of the injection.

JFM Papers
© 2019 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)


Ahmed, S. R., Ramm, G. & Faltin, G.1984 Some salient features of the time-averaged ground vehicle wake. SAE Technical Paper 840300.CrossRefGoogle Scholar
Apelt, C. J. & West, G. S. 1975 The effects of wake splitter plates on bluff body flow in the range 104 < Re < 5 × 104 . Part 2. J. Fluid Mech. 71 (01), 145160.CrossRefGoogle Scholar
Barros, D., Borée, J., Cadot, O., Spohn, A. & Noack, B. R. 2017 Forcing symmetry exchanges and flow reversals in turbulent wakes. J. Fluid Mech. 829, R1.CrossRefGoogle Scholar
Barros, D., Borée, J., Noack, B. R. & Spohn, A. 2016a Resonances in the forced turbulent wake past a 3D blunt body. Phys. Fluids 28 (6), 065104.CrossRefGoogle Scholar
Barros, D., Borée, J., Noack, B. R., Spohn, A. & Ruiz, T. 2016b Bluff body drag manipulation using pulsed jets and Coanda effect. J. Fluid Mech. 805, 422459.CrossRefGoogle Scholar
Bearman, P. W. 1967 The effect of base bleed on the flow behind a two-dimensional model with a blunt trailing edge. Aeronaut. Q. 18 (3), 207224.CrossRefGoogle Scholar
Bohorquez, P., Sanmiguel-Rojas, E., Sevilla, A., Jiménez-González, J. I. & Martínez-Bazán, C. 2011 Stability and dynamics of the laminar wake past a slender blunt-based axisymmetric body. J. Fluid Mech. 676, 110144.CrossRefGoogle Scholar
Bonnavion, G. & Cadot, O. 2018 Unstable wake dynamics of rectangular flat-backed bluff bodies with inclination and ground proximity. J. Fluid Mech. 854, 196232.CrossRefGoogle Scholar
Bonnavion, G. & Cadot, O. 2019 Boat-tail effects on the global wake dynamics of a flat-backed body with rectangular section. J. Fluids Struct. 89, 6171.CrossRefGoogle Scholar
Brackston, R. D., García De La Cruz, J. M., Wynn, A., Rigas, G. & Morrison, J. F. 2016 Stochastic modelling and feedback control of bistability in a turbulent bluff body wake. J. Fluid Mech. 802, 726749.CrossRefGoogle Scholar
Brackston, R. D., Wynn, A. & Morrison, J. F. 2018 Modelling and feedback control of vortex shedding for drag reduction of a turbulent bluff body wake. Intl J. Heat Fluid Flow 71, 127136.CrossRefGoogle Scholar
Cadot, O., Evrard, A. & Pastur, L. 2015 Imperfect supercritical bifurcation in a three-dimensional turbulent wake. Phys. Rev. E 91 (6), 063005.Google Scholar
Champagne, F. H., Pao, Y. H. & Wygnanski, I. J. 1976 On the two-dimensional mixing region. J. Fluid Mech. 74 (2), 209250.CrossRefGoogle Scholar
García de la Cruz, J. M., Brackston, R. D. & Morrison, J. F.2017 Adaptive base-flaps under variable cross-wind. SAE Technical Paper 2017-01-7000.CrossRefGoogle Scholar
García de la Cruz, J. M., Oxlade, A. R. & Morrison, J. F. 2017 Passive control of base pressure on an axisymmetric blunt body using a perimetric slit. Phys. Rev. Fluids 2 (4), 043905.CrossRefGoogle Scholar
Dalla Longa, L., Evstafyeva, O. & Morgans, A. S. 2019 Simulations of the bi-modal wake past three-dimensional blunt bluff bodies. J. Fluid Mech. 866, 791809.CrossRefGoogle Scholar
Dimotakis, P. E. 1991 Turbulent free shear layer mixing and combustion. In High Speed Flight Propulsion Systems, pp. 265340. American Institute of Aeronautics and Astronautics.Google Scholar
Evrard, A., Cadot, O., Herbert, V., Ricot, D., Vigneron, R. & Délery, J. 2016 Fluid force and symmetry breaking modes of a 3D bluff body with a base cavity. J. Fluids Struct. 61, 99114.CrossRefGoogle Scholar
Fabre, D., Auguste, F. & Magnaudet, J. 2008 Bifurcations and symmetry breaking in the wake of axisymmetric bodies. Phys. Fluids 20, 051702.CrossRefGoogle Scholar
Gerrard, J. H. 1966 The mechanics of the formation region of vortices behind bluff bodies. J. Fluid Mech. 25 (2), 401413.CrossRefGoogle Scholar
Grandemange, M., Cadot, O. & Gohlke, M. 2012 Reflectional symmetry breaking of the separated flow over three-dimensional bluff bodies. Phys. Rev. E 86 (3), 035302.Google ScholarPubMed
Grandemange, M., Gohlke, M. & Cadot, O. 2013a Bi-stability in the turbulent wake past parallelepiped bodies with various aspect ratios and wall effects. Phys. Fluids 25 (9), 095103.CrossRefGoogle Scholar
Grandemange, M., Gohlke, M. & Cadot, O. 2013b Turbulent wake past a three-dimensional blunt body. Part 1. Global modes and bi-stability. J. Fluid Mech. 722, 5184.CrossRefGoogle Scholar
Grandemange, M., Gohlke, M. & Cadot, O. 2014 Turbulent wake past a three-dimensional blunt body. Part 2. Experimental sensitivity analysis. J. Fluid Mech. 752, 439461.CrossRefGoogle Scholar
Greenblatt, D. & Wygnanski, I. J. 2000 The control of flow separation by periodic excitation. Prog. Aerosp. Sci. 36 (7), 487545.CrossRefGoogle Scholar
Jiménez-González, J. I., Sanmiguel-Rojas, E., Sevilla, A. & Martínez-Bazán, C. 2013 Laminar flow past a spinning bullet-shaped body at moderate angular velocities. J. Fluids Struct. 43, 200219.CrossRefGoogle Scholar
Jiménez-González, J. I., Sevilla, A., Sanmiguel-Rojas, E. & Martínez-Bazán, C. 2014 Global stability analysis of the axisymmetric wake past a spinning bullet-shaped body. J. Fluid Mech. 748, 302327.CrossRefGoogle Scholar
Kiya, M. & Abe, Y. 1999 Turbulent elliptic wakes. J. Fluids Struct. 13 (7–8), 10411067.CrossRefGoogle Scholar
Li, R., Barros, D., Borée, J., Cadot, O., Noack, B. R. & Cordier, L. 2016 Feedback control of bimodal wake dynamics. Exp. Fluids 57, 158.CrossRefGoogle Scholar
Littlewood, R. P. & Passmore, M. A. 2012 Aerodynamic drag reduction of a simplified squareback vehicle using steady blowing. Exp. Fluids 53 (2), 519529.CrossRefGoogle Scholar
Lucas, J. M., Cadot, O., Herbert, V., Parpais, S. & Délery, J. 2017 A numerical investigation of the asymmetric wake mode of a squareback Ahmed body – effect of a base cavity. J. Fluid Mech. 831, 675697.CrossRefGoogle Scholar
Mariotti, A., Buresti, G. & Salvetti, M. V. 2015 Connection between base drag, separating boundary layer characteristics and wake mean recirculation length of an axisymmetric blunt-based body. J. Fluids Struct. 55, 191203.CrossRefGoogle Scholar
Pasquetti, R. & Peres, N. 2015 A penalty model of synthetic micro-jet actuator with application to the control of wake flows. Comput. Fluids 114 (0), 203217.CrossRefGoogle Scholar
Pavia, G., Passmore, M. & Gaylard, A.2016 Influence of short rear end tapers on the unsteady base pressure of a simplified ground vehicle. SAE Technical Paper 2016-01-1590.CrossRefGoogle Scholar
Perry, A., Passmore, M. A. & Finney, A. 2015 Influence of short rear end tapers on the base pressure of a simplified vehicle. SAE Intl J. Passenger Cars–Mech. Syst. 8 (1), 317327.CrossRefGoogle Scholar
Pope, S. B. 2000 Turbulent Flows. Cambridge University Press.CrossRefGoogle Scholar
Rigas, G., Morgans, A. S., Brackston, R. D. & Morrison, J. F. 2015 Diffusive dynamics and stochastic models of turbulent axisymmetric wakes. J. Fluid Mech. 778, R2.CrossRefGoogle Scholar
Rigas, G., Oxlade, A. R., Morgans, A. S. & Morrison, J. F. 2014 Low-dimensional dynamics of a turbulent axisymmetric wake. J. Fluid Mech. 755, R5.CrossRefGoogle Scholar
Roshko, A. 1993 Perspectives on bluff body aerodynamics. J. Wind Engng Ind. Aerodyn. 49 (1–3), 79100.CrossRefGoogle Scholar
Rouméas, M., Gilliéron, P. & Kourta, A. 2009 Analysis and control of the near-wake flow over a square-back geometry. Comput. Fluids 38 (1), 6070.CrossRefGoogle Scholar
Sakamoto, H. & Haniu, H. 1990 A study on vortex shedding from spheres in a uniform flow. J. Fluids Engng 112, 386392.CrossRefGoogle Scholar
Sanmiguel-Rojas, E., Sevilla, A., Martínez-Bazán, C. & Chomaz, J. M. 2009 Global mode analysis of axisymmetric bluff-body wakes: stabilization by base bleed. Phys. Fluids 21 (11), 114102.CrossRefGoogle Scholar
Sevilla, A. & Martínez-Bazán, C. 2004 Vortex shedding in high Reynolds number axisymmetric bluff-body wakes: local linear instability and global bleed control. Phys. Fluids 16 (9), 34603469.CrossRefGoogle Scholar
Tanner, M. 1975 Reduction of base drag. Prog. Aerosp. Sci. 16 (4), 369384.CrossRefGoogle Scholar
Varon, E., Eulalie, Y., Edwige, S., Gilotte, P. & Aider, J. L. 2017 Chaotic dynamics of large-scale structures in a turbulent wake. Phys. Rev. Fluids 2, 034604.CrossRefGoogle Scholar
Viswanath, P. R. 1996 Flow management techniques for base and afterbody drag reduction. Prog. Aerosp. Sci. 32 (2), 79129.CrossRefGoogle Scholar
Volpe, R., Devinant, P. & Kourta, A. 2015 Experimental characterization of the unsteady natural wake of the full-scale square back Ahmed body: flow bi-stability and spectral analysis. Exp. Fluids 56, 99.CrossRefGoogle Scholar
Wassen, E., Eichinger, S. & Thiele, F. 2010 Simulation of active drag reduction for a squareback vehicle. In Active Flow Control II, pp. 241255.CrossRefGoogle Scholar
Wong, D. T. M. & Mair, W. A. 1983 Boat-tailed afterbodies of square section as drag-reduction devices. J. Wind Engng Ind. Aerodyn. 12 (2), 229235.CrossRefGoogle Scholar
Wood, C. J. 1964 The effect of base bleed on a periodic wake. Aeronaut. J. 68 (643), 477482.CrossRefGoogle Scholar
Wu, T. Y. T. 1972 Cavity and wake flows. Annu. Rev. Fluid Mech. 4 (1), 243284.CrossRefGoogle Scholar