| The present study discusses about the boil phenomena. The target flow field is the one observed in the Brahmaputra river, whose flow field has the area of 1,000m×200m, flow depth is about 9m, and discharge is about 3,500m3/s. The Reynolds number at the occurrence of the boil is 1.4×107. Three different method are compared; such as observed flow field by ADCP, modified observed-flow by the mass-consistent method, and the numerically simulated flow by the URANS implementing the observed geometry and flow properties. The URANS model successfully simulated the boil phenomena. Regarding the flow structure, three different characteristics are recognized, such as a) high upward velocity generates at the stoss side, b) longitudinal velocity affected by the a), and c) the down-ward velocity generated at the top of the crest as a paired type flow with the a). Relating to the occurrence of the boil, the higher bed shear stress also recognized by the ADCP observation and the simulated one. |
