LAUSR

ABSTRACT The flow patterns in a street are investigated in the case of flow exchanges with the sewer. The experimental facility includes one street and one circular pipe located below eventually connected by one or two drains. Compared to the runs without drain or with drainage, overflow creates a strong (up to 50%) increase of the streamwise velocity in the street, particularly, near the bottom, and a high degree of turbulence close to the drains and downstream. For overflow from one drain, the rearrangement of the flow is marked by an asymmetrical pattern with a main secondary current moving across the street; this latter pattern disappears when two drains are present. In field conditions, such an increase is likely to permit entrainment of people and cars by the flow. The experimental data sets could help to validate detailed CFD models aiming at extending the latter results in various flooding conditions.