1	Reproduction method of unsteady small-scale eddy field in the ocean 37-36273 Shinichiro Hirabayashi Supervisor: Prof. Toru Sato Assoc. Prof. Shoji Takechi
2	Contents Background Oceanic field measurement Wavelet spectral analysis Estimation of spatial information Turbulence forcing by numerical simulation (CFD) Conclusion
3	Small-scale turbulent diffusivity Small-scale (100m scale) diffusivity in the ocean is a parameter, which is applicable to the following problems.
4	Necessity for reproducing oceanic eddy field Lack of spatial information of the oceanic field Estimation of spatial information
5	Conventional methods to obtain diffusivity Shear probe sensor (Ex. XCP, TurboMAP) Energy dissipation rate is obtained from the vertical shear information obtained by a moving sensor.
6	Review Estimation of directional spectra of the coastal wave field Lygre and Krogstat (1986) and Hashimoto et al. (1997) Estimation of directional spectra of the wave field by using the maximum entropy method (MEM) Donelan et al. (1996) and Donelan (2001) Application of the wavelet transform to the directional wave analysis
7	"Reproduction method of 3D eddy..." Reproduction method of 3D eddy field in the deep ocean Sato (2004) Reproduction of the small-scale ocean turbulence with a CFD technique from the time-series of velocity obtained from one-point measurement Problem: Taylor’ hypothesis Ishikawa (2003) Trial of reproduction of the small-scale ocean turbulence with a combination of maximum likelihood method and CFD calculation from a set of time series of velocity obtained at 4 different points Problem: The assumption that the directional spectra do not change with time
8	Research objectives Development of a reproduction method of small-scale oceanic eddy field from limited data by the combination of the wavelet spectral analysis and the CFD Reproduction of the small-scale oceanic eddy field as the time-sequential 3D information Acquisition of the energy dissipation rate and eddy viscosity in the deep ocean
9	Contents Background Oceanic field measurement Wavelet spectral analysis Estimation of spatial information Turbulence forcing by numerical simulation (CFD) Conclusion
10	Design of measurement device Four 3D Acoustic Doppler Velocimeter (ADV), a stainless frame, and a fin Tetrahedron allocation Width & height: 2.5m and 3.5m Weight of frame: 150kg
11	Field measurement
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15	Contents Background Oceanic field measurement Wavelet spectral analysis Estimation of spatial information Turbulence forcing by numerical simulation (CFD) Conclusion
16	Wavelet transform
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19	Contents Background Oceanic field measurement Wavelet spectral analysis Estimation of spatial information Turbulence forcing by numerical simulation (CFD) Conclusion
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21	Reproduction of oceanic field
22	Reproduction of oceanic flow field
23	Time-sequential images of vorticity
24	Contents Background Oceanic field measurement Wavelet spectral analysis Estimation of spatial information Turbulence forcing by numerical simulation (CFD) Conclusion
25	Necessity of CFD calculation
26	Governing equations and models
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29	Validation of CFD calculation
30	Turbulence statistics
31	Effect of stratification
32	Contents Background Oceanic field measurement Wavelet spectral analysis Estimation of spatial information Turbulence forcing by numerical simulation (CFD) Conclusion
33	Conclusion A new reproduction method of the transient small-scale eddy field from a set of time series of field data was proposed. 4D (time series of 3D) oceanic field information of the scale of 30m was reproduced, which agree well with the original measured data. The high-wavenumber components of the energy spectra generated by the CFD follow the –5/3 power law well. The energy dissipation rate and the eddy viscosity obtained from the result of the CFD are of the order of 10^-9 m²/s³and 10^-3m²/s, respectively, both of which are reasonable in the deep ocean.
34	Future study Increase the accuracy of high-pass filter in the CFD calculation Application of the method to the wider area
35	Fin.
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37	Calibration experiment Towing experiment of ADVs
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