Skip to main content
SpringerLink
Log in

The flow regime in the turbulent near wake of a hemisphere

  • Originals
  • Published:
Experiments in Fluids Aims and scope Submit manuscript

Abstract

The work presented is a wind tunnel study of the near wake region behind a hemisphere immersed in three different turbulent boundary layers. In particular, the effect of different boundary layer profiles on the generation and distribution of near wake vorticity and on the mean recirculation region is examined. Visualization of the flow around a hemisphere has been undertaken, using models in a water channel, in order to obtain qualitative information concerning the wake structure.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

Abbreviations

C p :

pressure coefficient,\({{\left( {p - p_0 } \right)} \mathord{\left/ {\vphantom {{\left( {p - p_0 } \right)} {\tfrac{1}{2}\rho \tilde U^2 }}} \right. \kern-\nulldelimiterspace} {\tfrac{1}{2}\rho \tilde U^2 }}\)

D :

diameter of hemisphere

n :

vortex shedding frequency

p :

pressure on model surface

p 0 :

static pressure

Re :

Reynolds number,\({{\rho \tilde UD} \mathord{\left/ {\vphantom {{\rho \tilde UD} \mu }} \right. \kern-\nulldelimiterspace} \mu }\)

St :

Strouhal number,\({D \mathord{\left/ {\vphantom {D {\tilde U}}} \right. \kern-\nulldelimiterspace} {\tilde U}}\)

U, V, W :

local mean velocity components

\(\tilde U\) :

mean freestream velocity inX direction

U * :

shear velocity,\(\left( {{{\tau _w } \mathord{\left/ {\vphantom {{\tau _w } \rho }} \right. \kern-\nulldelimiterspace} \rho }} \right)^{1/2} = \left( {\overline {uw} } \right)^{1/2} \)

u, v, w :

velocity fluctuations inX, Y andZ directions

X :

Cartesian coordinate in longitudinal direction

Y :

Cartesian coordinate in lateral direction

Z :

Cartesian coordinate in direction perpendicular to the wall

itδ*:

boundary layer displacement thickness,\(\int\limits_0^\infty {\left( {1 - \frac{U}{{\tilde U}}} \right)dZ} \)

ε:

diameter of model surface roughness

θ:

elevation angleI

O :

boundary layer momentum thickness,\(\int\limits_0^\infty {\frac{U}{{\tilde U}}\left( {1 - \frac{U}{{\tilde U}}} \right)dZ} \)

τ w :

wall shearing stress

μ:

dynamic viscosity of fluid

ρ:

density of fluid

ψ:

streamfunction\(\int {\frac{{2U}}{{D\tilde U}}dZ} \)

ωx :

longitudinal component of vorticity,\(\frac{{\partial W}}{{\partial Y}} - \frac{{\partial V}}{{\partial Z}}\)

ωy :

lateral component of vorticity,\(\frac{{\partial W}}{{\partial X}} - \frac{{\partial U}}{{\partial Z}}\)

ω z :

vertical component of vorticity,\(\frac{{\partial V}}{{\partial X}} - \frac{{\partial U}}{{\partial Y}}\)

References

  • Achenbach, E. 1974: Vortex shedding from spheres. J. Fluid Mech. 62, 209–221

    Google Scholar 

  • Baker, C. J. 1980: The turbulent horseshoe vortex. J. Wind Eng. 6, 9–23

    Google Scholar 

  • Baker, D. J. 1966: A technique for the precise measurement of small fluid velocities. J. Fluid Mech. 26, 573–575

    Google Scholar 

  • Castro, I. P.; Robins, A. G. 1977: The flow around a surface mounted cube in uniform and turbulent streams. J. Fluid Mech. 79, 307–335

    Google Scholar 

  • Cheun, B. S. 1981: Separated shear layers behind two-dimensional square-edged bodies. Ph.D. Thesis, University of Surrey

  • Corke, T. C.; Nagib, H. M.; Tan-atichat, J. 1979: Flow near a building model in a family of surface layers, J. Ind. Aero. 5, 139–158

    Google Scholar 

  • Counihan, J. 1969: An improved method of simulating an atmospheric boundary layer in a wind tunnel. Atmos. Env. 3, 197–214

    Google Scholar 

  • Counihan, J. 1971: An experimental investigation of the wake behind a two-dimensional block and behind a cube in a simulated boundary layer flow. C.E.R.L. Lab. Note RD/L/N 115/71

  • Euromech 163. 1982: Surface mounted bluff bodies in turbulent boundary layers. Lisbon, November

  • Furuya, Y.; Miyata, M. 1972: Visual studies on the wake of a roughness element proximate to a wall. Memo. Fac. Eng., Nagoya Univ., No. 24, 278–293

  • Hansen, A. C. 1976: Vortex containing wakes of surface obstacles. Ph.D. Thesis, Colorado State University

  • Hawthorne, W. R.; Martin, M. E. 1955: The effect of density gradient and shear on the flow over a hemisphere. Proc. Royal Soc. A 232, 184–195

    Google Scholar 

  • Jacobs, W. 1938: Flow behind a single roughness element. Ing. Archiv. 9, 343–355

    Google Scholar 

  • Lemburg, R. 1973: On the wakes behind bluff bodies in a turbulent boundary layer. University of W. Ontario Rept. BLWT-3-73

  • Mason, P. J.; Morton B. R. 1984: Trailing vortices in the wakes of surface mounted obstacles. J. Fluid Mech. (to be publ.)

  • Mochizuki, M. 1961: Smoke observations on boundary layer transition caused by a spherical roughness element. J. Phys. Soc. Jpn. 16, 955–1008

    Google Scholar 

  • Ogawa, Y.; Oikawa, S.; Uehara, K. 1983: Field and wind tunnel study of the flow and diffusion around a model cube. 1. Flow measurements. Atmos. Env. 17, 1145–1159

    Google Scholar 

  • Okamoto, S. 1979: Turbulent shear flow behind sphere placed on plane boundary. Proc. 2nd Symp. on Turb. Shear Flows, 16.1–16.6

  • Okamoto, S. 1981: Turbulent shear flow behind hemisphere -cylinder placed on ground plane. Proc. 3rd Symp. on Turb. Shear Flows, 16.11–16.16

  • Okamoto, T.; Yagita, M.; Kataoka, S. 1977: Flow past cone placed on flat plate. Bull. Jpn. Soc. Mech. Eng. 20, 329–336

    Google Scholar 

  • Savory, E. 1984: Hemispheres in turbulent boundary layers. Ph.D. Thesis, University of Surrey

  • Savory, E.; Toy, N. 1984: Microcomputer control of wind tunnel instrumentation with on-line data acquisition and analysis. Software and Microsystems 3, 93–97

    Google Scholar 

  • Smith, C. R. 1983: A synthesized model of the near-wall behaviour in turbulent boundary layers. Proc. 8th Biennial Symp. on Turb., University of Missouri-Rolla

    Google Scholar 

  • Spencer, S. 1984: Investigation of the thymol blue flow visualization technique. Project Rept, Dept. of Civ. Eng., University of Surrey

  • Toy, N.; Moss, W. D.; Savory, E. 1983: Wind tunnel studies on a dome in turbulent boundary layers. J. Wind Eng. 12, 201–212

    Google Scholar 

  • Toy, N.; Savory, E. 1983: Turbulent shear flow in the near wake of a hemisphere. Proc. 8th Biennial Symp. on Turb., University of Missouri-Rolla, 16.1–16.12

    Google Scholar 

  • Tutu, N. K.; Chevray, R. 1975: Cross-wire anemometry in high intensity turbulence. J. Fluid Mech. 71, 785–800

    Google Scholar 

  • Wong, C. W. 1981: The structural behaviour of braced barrel vaults with particular reference to wind effects. Ph.D. Thesis, University of Surrey

Download references

Author information

Authors and Affiliations

  1. Department of Civil Engineering, University of Surrey, GU2 5XH, Guildford, Surrey, UK

    E. Savory & N. Toy

Authors
  1. E. Savory
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. N. Toy
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article

Savory, E., Toy, N. The flow regime in the turbulent near wake of a hemisphere. Experiments in Fluids 4, 181–188 (1986). https://doi.org/10.1007/BF00717812

Download citation

  • Received:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF00717812

Keywords

Search

Navigation