Unsteady numerical simulations were systematically conducted to investigate the transient flow characteristics around a staggered heat exchanger tube bundle. The vorticity distribution derived from numerical simulations was analyzed using Dynamic Mode Decomposition (DMD) for modal extraction and flow field reconstruction. The effects of the number of snapshots and singular value truncation order on the accuracy of reconstructed flow fields were studied. The results indicate that DMD enables accurate extraction of both vortical mode structures and their associated characteristic parameters, including frequencies and growth rates, from transient flow fields surrounding a staggered tube bundle. Flow field reconstructions obtained from dominant coherent modes exhibit strong agreement with high-fidelity numerical benchmarks. This confirms the effectiveness of the DMD methodology in resolving vortex-driven flow interactions in staggered tube bundle configurations. A minimum snapshot criterion is proposed based on the dimensionless period number, allowing direct determination of an appropriate number of snapshots with minimal computational error, which in turn substantially reduces computational costs. In terms of the energy retention ratio, a criterion for determining the optimal singular value truncation order is established, alleviating errors caused by overly aggressive truncation thresholds. This study provides theoretical insights into parameters selection for DMD analysis of complex flow fields around heat exchanger tube bundles.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |