Abstract:
This research aimed to study the appropriate wind patterns that induce satisfactory cross
ventilation in third class residential areas of hot- dry climate of central Sudan with focus on
Khartoum State, Al Haj Yousuf District, Block 10. The study also tended to investigate
factors affecting wind pattern in order to provide natural ventilation. Providing natural
ventilation is the main environmental aspect in residential areas, especially in the congested
third class areas, where natural ventilation is highly needed. The main problem is lack of
wind studies and wind effects on natural cross ventilation in urban residential areas in Sudan
where physical planning laws and building regulations are issued with no emphasis on wind
studies and its effects on urban residential areas. The study has employed wind analysis tools
and techniques, namely wind tunnels, and Computational Fluid Dynamics (CFD). Firstly,
two pilot models are studied to train on how to use CFD software. Then five models taken
from the study area have been studied. Velocity vectors and directions were plotted in the
five models at different heights (1.5m, 4.5m, 7.5m and 10.5m). The results show that the
wind speed dropped to 75 % when it collides with buildings. The vortexes appeared in the
internal courtyards. The wind regain it is normal speed after 12 times the height of the
building. It is noted that, high buildings block the wind to reach lower buildings. Wind speed
in the area between the house and boundary wall is ranging from 0.2m/s to 1.2m/s. There is
emergence of an area with triangular shape behind the high buildings (four storey) where the
speed in this area ranges between zero and 0.75m/s.
The study has concluded that the wind speed around buildings is sufficient to achieve natural
ventilation, except in low buildings just behind the high buildings, where the wind speed
required for natural ventilation in the dry and hot region is 1m/s. The researcher has
recommended that the buildings in third class residential areas should have the same heights
where the natural ventilation is needed. i.e. the heights should be uniformed either one storey,
two stories, three stories or four storey. The study has necessitated importance of open space
with 70m and 100m wide at least in the center of each group of houses with a single or four
stories respectively. Buildings should be designed in the form of square or rectangle, and
instead of U or Z shapes so as to minimize the generation of vortices and scattered wind in
the small yards.
