Tham khảo tài liệu 'particle-laden flow - ercoftac series phần 8', ngoại ngữ, anh ngữ phổ thông phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Laboratory model of two-dimensional polar beta-plane turbulence 293 Fig. 4. Snapshot of the flow evolution for experiment 15 at 4 s after stopping of the forcing. Reconstructed trajectories a velocity potential vorticity fields b . PV scale is cm 1 a b Fig. 5. Trend of the average zonal velocity Vz cm s with distance r cm from the center for the experiment 8 a and 15 b . a 1 b The differences between the two regimes can be also highlighted by analyzing the azimuthally averaged zonal velocity versus the distance r evaluated from the center of the domain pole . In the strong beta case figure 5a its distribution is characterized by a narrow peak around r 8 cm corresponding to the jet and by a relatively weak anticyclonic circulation in the central part of the domain. In the low beta case figure 5b the profile is not peaked at large radii but its maximum seems to be associated with a single strong vortex not centered on the origin see figure 4b forming as a result of the merging process. Further insight into the flow dynamics can be obtained by spectral analysis energy spectra evaluation is based on a two-dimensional Fourier transform in Cartesian coordinates. The one-dimensional spectrum with k ỵ kX ky is calculated by averaging both in time over fixed time intervals and over direction in wave-number space. In Figure 6 the energy spectra corresponding to the regime of intense beta effect is shown. The spectra are respectively 294 . Carnevale and A. Cenedese S. Espa M. Mariani Fig. 6. Energy spectra corresponding to the experiment 8. The spectra are calculated by an average on time intervals concerning various experiment phases T1 forced spectrum T2 time interval from 10 to 20 frames after the stop of the forcing T3 time interval from 20 to 45 frames after the stop of the forcing . The characteristic slopes k 5 k 5 3 and k-3 are shown in the box. evaluated in three different time ranges T1 when the forcing is still active T2 in the time interval from 10 to 20 frames
