Abstract
Low-frequency unsteadiness of a reattaching shear layer was studied in the flow behind a backward-facing step. Spectral data from a hot-wire probe showed that a substantial fraction of the measured turbulence intensity occurs at frequencies significantly lower than the large eddy passing frequency. Several thermal tuft probes were used simultaneously to identify the source of the low-frequency disturbances. It was concluded that the reattaching free shear layer undergoes a non-periodic, roughly two-dimensional, vertical motion. The motion causes the impingement point of the reattaching shear layer to drift slowly up- and downstream over a range of approximately two step heights. The likely cause of the low-frequency motion is an instantaneous imbalance between the entrain-ment rate from the recirculation zone and the reinjection rate near reattachment.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
Abbreviations
- F :
-
Frequency [Hz]
- h :
-
Step height = 5.08 cm
- U 0 :
-
Inlet free stream velocity
- x :
-
Streamwise coordinate
- x R :
-
Time mean reattachment location
- γ:
-
Percent of time that flow is in downstream direction
- θ:
-
Momentum thickness
References
Owen, F.K., Johnson, D.A.: “Separated Skin Friction Measurements — Source of Error: An Assessment and Elimination,” AIAA Paper No. 80-1409, 1980
Smith, C.R., Jr., Kline, S.J.: An experimental investigation of the transitory stall regime in two-dimensional diffusers, including the effects of periodically disturbed inlet conditions. J. Fluids Eng. 96, 11–15 (1974)
Eaton, J.K., Johnston, J.P.: “A Review of Research on Subsonic Turbulent Flow Reattachment,” AIAA paper 80-1438. AIAA J. (1981, to be published)
Tani, I., Iuchi, M., Komoda, H.: “Experimental Investigation of Flow Separation Associated with a Step or Groove,” Report No. 364, Aero Research Institute, Univ. of Tokyo (1961)
Chandrsuda, C: “A Reattaching Turbulent Shear Layer in Incompressible Flow”; Ph.D. Thesis, Dept. of Aeronautics, Imperial College of Science and Technology (1975)
Eaton, J., Johnston, J.P.: “An Evaluation of Data for the Backward-Facing Step Flow,” Rpt. Conf. on Complex Turbulent Flows, Stanford Univ. (1980)
Goldschmidt, V.W., Bradshaw, P.: Flapping of a plane jet. Phys. Fluids 16, 354–355 (1973)
de Gortari, C.J.: “An Experimental Study of the Flapping Motion of a Turbulent Plane Jet”; Ph.D. Thesis, Purdue University (1978)
Rockwell, D., Naudascher, E.: Self-sustained oscillations of impinging free shear layers. Ann. Rev. Fluid Mech. 11, 67–94 (1979)
Rockwell, D., Knisely, C: Vortex edge interaction mechanisms for generating low-frequency components. Phys. Fluids 23, 239–240 (1980)
Rockwell, D.: Private communication (1980)
McGuinness, M.: “Flow with a Separation Bubble — Steady and Unsteady Aspects”; Ph.D. Dissertation, Cambridge University (1978)
Eaton, J.K., Johnston, J.P., Jeans, A.H.: “Measurements in a Reattaching Turbulent Shear Layer,” Proceedings of the 2nd Symposium on Turbulent Shear Flows, London (1979)
Westphal, R.V., Johnston, J.P.: Private communication (1981)
Eaton, J.K., Jeans, A.H., Ashjaee, J., Johnston, J.P.: A wall-flow-direction probe for use in separating and reattaching flows. J. Fluids Eng. 101, 364–366 (1979)
Bradbury, L.J.S., Castro, I.P.: A pulsed-wire technique for velocity measurements in highly turbulent flow. J. Fluid Mech. 49, 657–691 (1971)
Eaton, J.K., Westphal, R.V., Johnston, J.P.: “Two New Instruments for Flow Direction and Skin-Friction Measurements in Separated Flows,” ISA 2nd Int. Symposium on Flow (April 1981)
Mellor, G.L., Celenligil, M.C.: “Summary of Computations of Flows 0331, 0421, and 0431,” 1980-81 Stanford Conferences on Complex Turbulent Flows (1981)
Armaly, B.F., Durst, F., Schönung, R.: “Measurements and Predictions of Flow Downstream of a Two-Dimensional Single Backward-Facing Step,” Report SFB80/ET/172, SFB80 Universität Karlsruhe (1980)
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 1982 Springer-Verlag Berlin Heidelberg
About this paper
Cite this paper
Eaton, J.K., Johnston, J.P. (1982). Low Frequency Unsteadyness of a Reattaching Turbulent Shear Layer. In: Bradbury, L.J.S., Durst, F., Launder, B.E., Schmidt, F.W., Whitelaw, J.H. (eds) Turbulent Shear Flows 3. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-95410-8_16
Download citation
DOI: https://doi.org/10.1007/978-3-642-95410-8_16
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-642-95412-2
Online ISBN: 978-3-642-95410-8
eBook Packages: Springer Book Archive