Abstract
Thermally stratified unsteady flow caused by two-dimensional surface discharge of warm water into a rectangular reservoir is investigated. Experimental study is focused on the rapidly developing thermal diffusion at small Richardson number.
The basic objectives are to develop a measurement system for the unsteady flow phenomena and to study the interfacial mixing between a flowing layer of warm water and the underlying body of cold water.
Mean velocity field measurement is carried out by using NMR-CT (Nuclear Magnetic Resonance — Computerized Tomography). It detects a quantitative flow image of any desired section in any direction of flow. Transient mean temperature profiles are obtained by fine thermocouple arrays and a microcomputer-based data acquisition system.
Results show that the warm layer penetrates more rapidly into the cold layer at smaller Richardson number because of decrease instability. This is clearly verified by flow visualization using thymol blue solution. It is found that the transport of heat across the interface is more vigorous than that of momentum.
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References
Bloch, F. 1946: Nuclear induction. Phys. Rev. 70, 460–475
Boyle, D. R.; Golay, M. W. 1983: Measurement of a recirculating, two-dimensional, turbulent flow and comparison to model predictions. Part 2: Transient Case. Trans. ASME, J. Fluids Eng. 105, 447–454
Cho, Z. H.; Oh, C. H.; Kim, Y. S.; Mun, C. W.; Lee, S. J.; Chung, M. K. 1985: A new fast NMR flow velocity imaging. J. of Appl. Phys. (to appear)
Cho, Z. H.; Kim, H. S.; Song, H. B.; Cumming, J. 1982: Fourier transform NMR tomographic imaging. Proc. IEEE 70, 1152–1173
Ellison, T. H.; Turner, J. S. 1959: Turbulent entrainment in stratified flows. J. Fluid Mech. 6, 423–448
Gibson, M. M.; Launder, B. E. 1978: Ground effects on pressure fluctuations in the atmospheric boundary layer. J. Fluid Mech. 80, 491–511
Jeffreys, D. 1925: The flow of water in an inclined channel of rectangular section. Philos. Mag. Set. A 107, 189–195
Komori, S.; Ueda, H.; Ogino, F.; Mizushina, T. 1983: Turbulence structure in stably stratified open-channel flow. J. Fluid Mech. 130, 13–26
Launder, B. E. 1975: On the effects of a gravitational field on the turbulent transport of heat and momentum. J. Fluid Mech. 63, 569–581
Lee, S. J. 1986: Unsteady turbulent thermal diffusion of two-dimensional surface discharge of heated water into a rectangular reservoir. Ph.D. Thesis, KAIST
Mizushina, T.; Ogino, F.; Ueda, H.; Komori, S. 1979: Application of laser Doppler velocimetry to turbulence measurement in non-isothermal flow. Proc. R. Soc. Lond. Set. A366, 63–79
Moran, P. R. 1982: A flow velocity zeugmatographic interlace for NMR imaging in humans. Mag. Res. Imaging 1, 197–203
Oh, C. H.; Cho, Z. H. 1985: A new phase method using slice selection gradient for high speed flow velocity measurement in NMR tomography. Phys. Med. & Biol. (to appear)
Piat, J. F.; Hopfinger, E. J. 1981: A boundary layer topped by a density interface. J. Fluid Mech. 113, 411–432
Polk, Jr. E. M.; Benedict, B. A.; Parker, F. L. 1974: Dispersion of thermal discharges in bodies of water. Chem. Eng. Prog. Symp. Ser. 67, 111–119
Stefan, H. 1970: Stratification of flow from channel into deep lake. Trans. ASCE 67, 1417–1434
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Lee, S.J., Chung, M.K., Mun, C.W. et al. Experimental study of thermally stratified unsteady flow by NMR-CT. Experiments in Fluids 5, 273–281 (1987). https://doi.org/10.1007/BF00279742
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DOI: https://doi.org/10.1007/BF00279742