Modeling of flood in urban areas with a porosity model: Directional effects

The porosity model is a simplified model of the propagation of floods through urban areas. It is based on the idea that a city can be assimilated to a large-scale porous medium where the pores would be the streets and the solid matrix the buildings. The urban medium is anisotropic because of the presence of larger and wider avenues creating preferential paths. Here the anisotropy is taken into account via an eddy head loss term. A new expression for this term taking into account anisotropic effects is proposed, including a drag tensor and a directional parameter. Experiments were conducted in laboratory on a simplified city layout of 5×5 buildings, with different streets width, and placed either aligned either skewed with the main flow direction. The head loss expression is calibrated and then validated against these experimental data. © 2012 Taylor and Francis Group