Computing pollutant dispersion in an urban flood flow
The risks associated with flooding in urban areas are numerous and well studied in the literature. They mainly cover the risks for people, vehicles & street furniture to be carried away by the flow within the flooded streets. However, the health risk linked to sewer overflows, truck overturning, factory leaching, etc. has been largely neglected. Here, we study experimentally and numerically the transport of a simplified pollutant (liquid, isodense & miscible) within a simplified flooded street network (urban skeletal geometry shown in the attached figure) affected by a flood, also in simplified conditions (steady flow regime). This study highlights the link between the specific hydrodynamics of a flooded street network and the dispersion of a scalar in the streets or in an urban block. This dataset is then available to adjust operational (or more elaborate) numerical models.
In a second part, I will present a review of the studies, available in the literature, aiming at calculating the transport of a scalar in a shallow free surface flow, based on the 2D (horizontal) advection-diffusion equation averaged over the vertical axis (from the bottom to the free surface). I will show the additional difficulty in adjusting the diffusivity tensor to be used in such a 2D study compared to a 3D calculation (generally based on the use of a turbulent Schmidt coefficient). I will conclude by showing the first numerical results obtained from a simple diffusivity tensor and we will then discuss together the implementation of more elaborate numerical approaches.
Contact Juan Ignacio Polanco for more information or to schedule a discussion with the seminar speaker.