Abstract:
In our present research, we focus on the modeling of airflow related to natural disasters, such as
sand accumulation, with urban form studies. The objective is to find which urban form can promote sand passing and reduce as much as possible stagnation of sand in the building area (streets, alleys, etc.). The urban form design will be discussed through the simulation of airflow by using Computational Fluid Dynamics (CFD). In terms of simulation, we simulated the airflow behavior, which is responsible of sand stagnation in some specific configurations. A flat ground was chosen with a first configuration, which was varied to test each time a current airflow behavior in this
configuration. This modeling is made possible following an appropriate turbulence model. In this study, a correlation was made between urban wind speed and morphological parameters such as aspect ratio, building geometry and building density. According to our theoretical references, this correlation shows that urban wind speed can help reduce sand stagnation with proper values of these parameters. Therefore, through the urban form study we can promote wind speed and blow away the accumulated sand till the urban limits.
Machine summary:
Modeling Airflow in Urban Form against Sand Accumulation (case Study: Saltation in the Town of Timimoun in Southern Algeria) 1*Djamel Mestoul, 2Rafik Bensalem, 3Luc Adolphe 1Ph. D.
2016 In our present research, we focus on the modeling of airflow related to natural disasters, such as sand accumulation, with urban form studies.
ABSTRACT: Keywords: Computational Fluid Dynamics (CFD), Sand accumulation, Saltation, Urban form, Urban geometry, Wake effect INTRODUCTION Timimoun is a town and commune, and the capital of Timimoun District, in Adrar Province, south-central Algeria.
Name of model Type (A) Height (H) [m] 5 Length (L) [m] 10 Distance between volumes ∆ [m] 15 Ratio H/L 0,5 Ratio L/∆ 0,66 MATERIELS AND METHODS Given the fluid nature of wind, the most critical factor in controlling the airflow at the urban scale is the space geometry.
Through the CFD simulation, we will try to define the aspect ratio (H/D) and (E/D) of urban form, which is capable to maintain a wind velocity the order of 2 to 4m/s in the built environment.
According to the literature (Bagnold, 1941; Pethick, 1984; Anderson & Haff 1991;Kok & Renno 2009), we suppose that this velocity would still be able to put in motion the accumulated sand grains under the raised buildings remove them.
It seems that the model type (1) (raised 4 m above the ground) can produce a wind velocity of 2-5m/s witch is able to lift the accumulated sand in buildings.
/ Fig. 12: Wind velocity contours around buildings in an urban length E with six rows.