Atushiro Yorozuya, Ahmad Ali Gul, Tsuyoshi Hoshino, Shoji Okada
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.
