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The role of streamwise vorticity in the near-field entrainment of round jets

Published online by Cambridge University Press:  26 April 2006

Dorian Liepmann
Department of Applied Mechanics and Engineering Science, University of California, San Diego, CA 92093-0411, USA Present address: Department of Mechanical Engineering, University of California Berkeley, CA 94720, USA.
Morteza Gharib
Department of Applied Mechanics and Engineering Science, University of California, San Diego, CA 92093-0411, USA Present address: Department of Aeronautics, California Institute of Technology, 1201 E. California Blvd., Pasadena, CA 91125, USA.


The role of streamwise vortex structures in the near-field (x/d < 10) evolution of a round jet is examined. In free shear layers the streamwise vorticity develops into Bernal-Roshko structures which are streamwise vortex pairs. Similar structures are shown to exist in round jets. These structures, which evolve and amplify in the braid region between primary vortical structures, are shown to drastically alter the entrainment process in the near field and to increase the rate at which fluid is entrained into the jet. As the flow evolves downstream, the efficiency of the streamwise vorticity in entraining fluid increases relative to that of the azimuthal vorticity. Beyond the end of the potential core regime, the entrainment process is mainly controlled by streamwise vorticity. These processes are identified via flow visualization and confirmed by detailed global entrainment measurements.

Research Article
© 1992 Cambridge University Press

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Agui, J. C. & Hesselink L. 1988 Flow visualization and numerical analysis of a coflowing jet: a three-dimensional approach. J. Fluid Mech. 191, 1935.Google Scholar
Ashurst, W. T. & Meiburg E. 1988 Three-dimensional shear layers via vortex dynamics. J. Fluid Mech. 189, 87116.Google Scholar
Bernal L. P. 1981 The coherent structure in turbulent mixing layers. II Secondary streamwise vortex structure. Ph.D. thesis, California Institute of Technology.
Bernal, L. P. & Roshko A. 1986 Streamwise vortex structure in plane mixing layers. J. Fluid Mech. 170, 499525.Google Scholar
Breidenthal R. E. 1981 Structure in turbulent mixing layers and wakes using a chemical reaction. J. Fluid Mech. 109, 124.Google Scholar
Browand, F. K. & Laufer J. 1975 The role of large scale structures in the initial development of a circular jet. 4th Biennial Symp. on Turbulence in Liquids, University of Missouri-Rolla.
Brown, G. L. & Roshko A. 1974 On density effects and large structures in turbulent mixing layers. J. Fluid Mech. 64, 775816.Google Scholar
Cimbala J. M., Nagib, H. M. & Roshko A. 1988 Large structure in the far wakes of two-dimensional bluff bodies. J. Fluid Mech. 190, 265298.Google Scholar
Corcos, G. M. & Lin S. J. 1984 The mixing layer: deterministic models of a turbulent flow. Part 2. The origin of three-dimensional flow. J. Fluid Mech. 139, 6795.Google Scholar
Crow, S. C. & Champagne F. H. 1971 Orderly structure in jet turbulence. J. Fluid Mech. 48, 547591.Google Scholar
Dimotakis P. E., Miake-Lye, R. C. & Papantoniou D. A. 1983 Structure and dynamics of round turbulent jets Phys. Fluids 26, 31853192.Google Scholar
Gharib, M. & Willert C. 1989 Particle tracing revisited. In Advancements in Fluid Mechanic Measurements (ed. M. Gad-el-Hak), pp. 107126. Springer.
Jimenez J. 1983 A spanwise structure in the plane shear layer. J. Fluid Mech. 132, 319336.Google Scholar
Konrad J. H. 1976 An experimental investigation of mixing in two-dimensional turbulent shear flows with applications to diffusion-limited chemical reactions. Ph.D. thesis, California Institute of Technology.
Lasheras J. C., Cho, J. S. & Maxworthy T. 1986 On the origin and evolution of streamwise vortical structures in a plane, free shear layer. J. Fluid Mech. 172, 231258.Google Scholar
Liepmann D. 1990 The near-field dynamics and entrainment field of submerged and near-surface jets. Ph.D. thesis, University of California, San Diego.
Liepmann D. 1991 Streamwise vorticity and entrainment in the near field of a round jet Phys. Fluids A 3, 11791187.Google Scholar
Liepmann, D. & Gharib M. 1989 The effect of a free surface on the stability of a round jet. Bull. Am. Phys. Soc. 34, 2320.Google Scholar
Liepmann, H. W. & Laufer. J. 1947 Investigation of free turbulent mixing. NACA Tech. Note 1258.Google Scholar
Lin, S. J. & Corcos G. M. 1984 The mixing layer: deterministic models of a turbulent flow. Part 3. The effect of plane strain on the dynamics of streamwise vortices. J. Fluid Mech. 141, 139178.Google Scholar
Martin, J. E. & Meiburg, E. 1991 Numerical investigation of three-dimensionally evolving jets subject to axisymmetric and azimuthal perturbations. J. Fluid Mech. 230, 271318.Google Scholar
Meiburg, E. & Lasheras J. C. 1988 Experimental and numerical investigation of the three-dimensional transition in plane wakes. J. Fluid Mech. 190, 137.Google Scholar
Meiburg E., Lasheras, J. C. & Ashurst W. T. 1988 Topology of the vorticity field in three-dimensional shear layers and wakes. Fluid Dyn. Res. 3, 140148.Google Scholar
Monkewitz P. A., Lehman B., Barsikow, B. & Bechert. D. W. 1989 The spreading of self-excited hot jets by side-jets Phys. Fluids A 1, 446454.Google Scholar
Ricou, F. P. & Spalding D. B. 1961 Measurements of entrainment by axisymmetrical turbulent jets. J. Fluid Mech. 11, 2132.Google Scholar
Rogers, M. M. & Moser. R. D. 1992 The three-dimensional evolution of a plane mixing layer: the Kelvin-Helmholtz rollup. J. Fluid Mech. 243, 183226.Google Scholar
Widnall, S. E. & Sullivan J. P. 1973 On the stability of vortex rings Proc. R. Soc. Lond. A 332, 335353.Google Scholar
Willert, C. E. & Gharib M. 1991 Digital particle image velocimetry. Exps. Fluids 10, 181193.Google Scholar
Winant, C. D. & Browand F. K. 1974 Vortex pairing: the mechanism of turbulent mixing-layer growth at moderate Reynolds number. J. Fluid Mech. 63, 237255.Google Scholar
Wygnanski, I. & Fiedler H. 1969 Some measurements in the self-preserving jet. J. Fluid Mech. 38, 577612.Google Scholar
Yule A. J. 1978 Large-scale structure in the mixing layer of a round jet. J. Fluid Mech. 89, 413432.Google Scholar