resulting from natural ventilation predominates. Rico-García (2008) found that
applying temperatures as the main driving forces for the buoyancy effect provides
a simple way to study ventilation and inner air patterns. Vera et al. (2010a)
observed that differences in temperature and ventilation rates strongly influence
the movement of air, pushing it through openings where space is colder, while
creating rising air currents when it is hot. Majdoubi et al. (2009) showed that the
buoyancy forces induced by air temperature and increased humidity result in loops
of air between the crop and the roof windows, which in turn tend to accelerate the
pace of evacuation of heat and water vapor, enhancing indoor climate. Fidaros
et al. (2010) studied turbulence in Greek greenhouses and found that external
temperature variation is very important because internal temperature is determined
by convection induced by the input current. The housing area had a higher circulation in the center of the greenhouse near the deck and in the corners of the
ground, where the effect of the input current is weak. Defraeye et al. (2010) used a
RANS turbulence model in CFD simulations to evaluate heat transfer by forced
convection at the surface of a cube immersed in a turbulent boundary layer for
applications in the atmospheric boundary layer (ABL), where wind speed is not
disturbed at a height of 10 m. In a study of airfoil wakes, three turbulence models
were simulated by Roberts and Cui (2010); the Reynolds Stress Model (RSM) is
superior to the k-e model, and when a time-dependent solution is necessary, LES is
the desired option. However, LES does require the airfoil geometry to be included
in the domain because it performs poorly when given only inlet velocities, turbulence kinetic energy, and eddy dissipation at the trailing edge of the airfoil.
According to Bournet and Boulard (2010), although they have been used for a long
time in both agriculture and environmental studies, less empirical approaches to
turbulence based on the use of LES have never been applied to greenhouse climate
modeling and might perhaps be used to look for a solution to this complex
situation.
Inside buildings, it is difficult to maintain a thermally stratified space with low
ceilings, such as in offices and houses. Vera et al. (2010b) studied buoyancy in
enclosed spaces, drawing the following conclusions:
(a) Rising air currents and the exchange of humidity are closely related to the
temperature difference between the lower and upper spaces. Low temperature
in the upper space promotes the exchange of humidity and airflow through the
opening; the hotter you are, the greater the restriction of air and humidity
transport.
(b) The existence of upward air currents when the space is warmer than the
bottom is caused by local conditions such as nonuniform temperature distributions in the upper space and convective warm currents of the base and
humidity source.
(c) Compared with conditions without mechanical ventilation, ventilation severely
restricts the flow of air through the opening.
352
G. De la Torre-Gea et al.
applying temperatures as the main driving forces for the buoyancy effect provides
a simple way to study ventilation and inner air patterns. Vera et al. (2010a)
observed that differences in temperature and ventilation rates strongly influence
the movement of air, pushing it through openings where space is colder, while
creating rising air currents when it is hot. Majdoubi et al. (2009) showed that the
buoyancy forces induced by air temperature and increased humidity result in loops
of air between the crop and the roof windows, which in turn tend to accelerate the
pace of evacuation of heat and water vapor, enhancing indoor climate. Fidaros
et al. (2010) studied turbulence in Greek greenhouses and found that external
temperature variation is very important because internal temperature is determined
by convection induced by the input current. The housing area had a higher circulation in the center of the greenhouse near the deck and in the corners of the
ground, where the effect of the input current is weak. Defraeye et al. (2010) used a
RANS turbulence model in CFD simulations to evaluate heat transfer by forced
convection at the surface of a cube immersed in a turbulent boundary layer for
applications in the atmospheric boundary layer (ABL), where wind speed is not
disturbed at a height of 10 m. In a study of airfoil wakes, three turbulence models
were simulated by Roberts and Cui (2010); the Reynolds Stress Model (RSM) is
superior to the k-e model, and when a time-dependent solution is necessary, LES is
the desired option. However, LES does require the airfoil geometry to be included
in the domain because it performs poorly when given only inlet velocities, turbulence kinetic energy, and eddy dissipation at the trailing edge of the airfoil.
According to Bournet and Boulard (2010), although they have been used for a long
time in both agriculture and environmental studies, less empirical approaches to
turbulence based on the use of LES have never been applied to greenhouse climate
modeling and might perhaps be used to look for a solution to this complex
situation.
Inside buildings, it is difficult to maintain a thermally stratified space with low
ceilings, such as in offices and houses. Vera et al. (2010b) studied buoyancy in
enclosed spaces, drawing the following conclusions:
(a) Rising air currents and the exchange of humidity are closely related to the
temperature difference between the lower and upper spaces. Low temperature
in the upper space promotes the exchange of humidity and airflow through the
opening; the hotter you are, the greater the restriction of air and humidity
transport.
(b) The existence of upward air currents when the space is warmer than the
bottom is caused by local conditions such as nonuniform temperature distributions in the upper space and convective warm currents of the base and
humidity source.
(c) Compared with conditions without mechanical ventilation, ventilation severely
restricts the flow of air through the opening.
352
G. De la Torre-Gea et al.