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PARTICLE-LADEN FLOW - ERCOFTAC SERIES Phần 4

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Tham khảo tài liệu 'particle-laden flow - ercoftac series phần 4', ngoại ngữ, anh ngữ phổ thông phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 122 L.J.A. van Bokhoven et al. t A - C3 . D 10-1 b 10-1 100 T Fig. 3. a Time evolution of the velocity derivative skewness Sdui during and after the isotropic precalculation for different viscosities V. Background rotation in cases A C3 and D is applied at tini 5.0 4.0 and 2.0 respectively. For reference the isotropic precalculations have been prolonged. b Log-log plot showing the vorticity skewness S 3 as a function of the scaled shifted time T for cases A C3 and D. S . . appears to depend inversely on time tini i.e. shorter precalculations yield higher final values of SW3. The behavior observed in Fig. 3 b may partly be ascribed to slight differences in SỹiUi at time tini. 123 Refined vorticity statistics of decaying rotating 3D turbulence á Ư 10-1 10 1 100 T Fig. 4. As Fig. 3 but for different durations of the isotropic precalculation. Background rotation in cases B1-B4 is applied at tini 2.0 4.0 6.0 and 8.0 respectively. Finally Fig. 5 shows the time evolution of SỹiUi and S . . for various background rotation rates viz. f 0.5 2.5 5.0 and 10.0 cases C1-C4 . Clearly a lower background rotation rate results in a larger final value of SW3. This result expresses the fact that the asymmetry between cyclonic and anticyclonic structures is more pronounced at low rotation rates than at high rotation rates. It is remarked that similar results were extracted from lower resolution N 144 calculations. 124 L.J.A. van Bokhoven et al. 0.6 0.5 0.4 0.3 0.2 0.1 0 123456789 10 T Fig. 5. As Fig. 3 but for different background rotation rates. Background rotation in cases C1-C4 is applied at tini 4.0. Third Order Vorticity Correlations Figure 6 shows the time evolution of all nontrivial VTCs for various background rotation rates. The following three observations are made 1 w3 W1W3 and yxW are much smaller than unity and fluctuate around zero 2 W1W3 2 3 and 3 are clearly nonzero and 3 the ratio w2w3 w 2w3 not shown is found to fluctuate around unity. These results are consistent with