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Windcatcher
A windcatcher, wind tower, or wind scoop ( ar, برجيل ; fa, بادگیر) is a traditional architectural element used to create cross ventilation and passive cooling in buildings. Windcatchers come in various designs: unidirectional, bidirectional, and multidirectional. Windcatchers are widely used in North Africa and West Asia. Iran, especially in the south of Fars province and Hormozgan province, and other countries around the Persian Gulf have used windcatchers for the past three thousand years. Neglected by modern architects in the latter half of the 20th century, the early 21st century saw them used again, to increase ventilation and cut power demand for air-conditioning. Generally, the cost of construction for a windcatcher-ventilated building is less than that of a similar building with conventional heating, ventilation, and air conditioning (HVAC) systems. The maintenance costs are also lower. Unlike powered air-conditioning and fans, windcatchers are silent and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Passive Ventilation
Passive ventilation is the process of supplying air to and removing air from an indoor space without using mechanical systems. It refers to the flow of external air to an indoor space as a result of pressure differences arising from natural forces. There are two types of natural ventilation occurring in buildings: ''wind driven ventilation'' and ''buoyancy-driven ventilation''. Wind driven ventilation arises from the different pressures created by wind around a building or structure, and openings being formed on the perimeter which then permit flow through the building. Buoyancy-driven ventilation occurs as a result of the directional buoyancy force that results from temperature differences between the interior and exterior. Since the internal heat gains which create temperature differences between the interior and exterior are created by natural processes, including the heat from people, and wind effects are variable, naturally ventilated buildings are sometimes called "breathi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cross Ventilation
Cross-ventilation is a natural phenomena where wind, fresh air or a breeze enters upon an opening, such as a window, and flows directly through the space and exits through an opening on the opposite side of the building (where the air pressure is lower). This produces a cool stream of air and as well as a current across the room from the exposed area to the sheltered area. Other terms used for the effect include, cross-breeze, cross-draft, wind effect ventilation and cross-flow ventilation.Wind ventilation and cross ventilation Connection Magazines Windows or vents positioned on opposite sides of the room allow passive breezes a pathway through the structure, which circulate the air and provide passive cooling. Cross-ventilation is a wind-driven effect and requires no |
Salsabil (fountain)
A salsabil (or salasabil), also known as a shadirwan, is a type of fountain which maximizes the surface area of the water. It is used for evaporative cooling of buildings, cooling and aeration of drinking water, and ornament (it has also been used to prevent eavesdropping). The water may flow in a thin sheet or thin streams, often over a wavy surface with many little waterfalls. Its use extends from southern Spain through north Africa and the Middle East to northern India. Etymology and name The name ''salsabil'' likely derives from a Qur'anic reference. The term ''shadirwan'' is also used for devices for aerating drinking water. However, the term ''shadirwan'' or ''shadirvan'' has slightly different uses in other cultures, such as designating a central ablutions fountain for a mosque courtyard in Turkish (see ''shadirvan''). Design and setting The water flows in a manner designed to maximize the surface area, and thus evaporation. A salsabil may be a near-vertical marble ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Passive Cooling
Passive cooling is a building design approach that focuses on heat gain control and heat dissipation in a building in order to improve the indoor thermal comfort with low or no energy consumption. This approach works either by preventing heat from entering the interior (heat gain prevention) or by removing heat from the building (natural cooling). Natural cooling utilizes on-site energy, available from the natural environment, combined with the architectural design of building components (e.g. building envelope), rather than mechanical systems to dissipate heat. Therefore, natural cooling depends not only on the architectural design of the building but on how the site's natural resources are used as heat sinks (i.e. everything that absorbs or dissipates heat). Examples of on-site heat sinks are the upper atmosphere (night sky), the outdoor air (wind), and the earth/soil. Passive cooling is an important tool for design of buildings for climate change adaptationreducing dependency o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chimney
A chimney is an architectural ventilation structure made of masonry, clay or metal that isolates hot toxic exhaust gases or smoke produced by a boiler, stove, furnace, incinerator, or fireplace from human living areas. Chimneys are typically vertical, or as near as possible to vertical, to ensure that the gases flow smoothly, drawing air into the combustion in what is known as the stack, or chimney effect. The space inside a chimney is called the ''flue''. Chimneys are adjacent to large industrial refineries, fossil fuel combustion facilities or part of buildings, steam locomotives and ships. In the United States, the term ''smokestack industry'' refers to the environmental impacts of burning fossil fuels by industrial society, including the electric industry during its earliest history. The term ''smokestack'' (colloquially, ''stack'') is also used when referring to locomotive chimneys or ship chimneys, and the term ''funnel'' can also be used. The height of a chim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laminar Flow
In fluid dynamics, laminar flow is characterized by fluid particles following smooth paths in layers, with each layer moving smoothly past the adjacent layers with little or no mixing. At low velocities, the fluid tends to flow without lateral mixing, and adjacent layers slide past one another like playing cards. There are no cross-currents perpendicular to the direction of flow, nor eddies or swirls of fluids. In laminar flow, the motion of the particles of the fluid is very orderly with particles close to a solid surface moving in straight lines parallel to that surface. Laminar flow is a flow regime characterized by high momentum diffusion and low momentum convection. When a fluid is flowing through a closed channel such as a pipe or between two flat plates, either of two types of flow may occur depending on the velocity and viscosity of the fluid: laminar flow or turbulent flow. Laminar flow occurs at lower velocities, below a threshold at which the flow becomes turbulent. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flow Separation
In fluid dynamics, flow separation or boundary layer separation is the detachment of a boundary layer from a surface into a wake. A boundary layer exists whenever there is relative movement between a fluid and a solid surface with viscous forces present in the layer of fluid close to the surface. The flow can be externally, around a body, or internally, in an enclosed passage. Boundary layers can be either laminar or turbulent. A reasonable assessment of whether the boundary layer will be laminar or turbulent can be made by calculating the Reynolds number of the local flow conditions. Separation occurs in flow that is slowing down, with pressure increasing, after passing the thickest part of a streamline body or passing through a widening passage, for example. Flowing against an increasing pressure is known as flowing in an adverse pressure gradient. The boundary layer separates when it has travelled far enough in an adverse pressure gradient that the speed of the boundary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wind Gradient
In common usage, wind gradient, more specifically wind speed gradient or wind velocity gradient, or alternatively shear wind, is the vertical component of the gradient of the mean horizontal wind speed in the lower atmosphere. It is the rate of increase of wind strength with unit increase in height above ground level. In metric units, it is often measured in units of meters per second of speed, per kilometer of height (m/s/km), which reduces to the standard unit of shear rate, inverse seconds (s−1). Simple explanation Surface friction forces the surface wind to slow and turn near the surface of the Earth, blowing directly towards the low pressure, when compared to the winds in the nearly frictionless flow well above the Earth's surface. This layer, where surface friction slows the wind and changes the wind direction, is known as the planetary boundary layer. Daytime solar heating due to insolation thickens the boundary layer as winds warmed by contact with the ear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lapse Rate
The lapse rate is the rate at which an atmospheric variable, normally temperature in Earth's atmosphere, falls with altitude. ''Lapse rate'' arises from the word ''lapse'', in the sense of a gradual fall. In dry air, the adiabatic lapse rate is 9.8 °C/km (5.4 °F per 1,000 ft). It corresponds to the vertical component of the spatial gradient of temperature. Although this concept is most often applied to the Earth's troposphere, it can be extended to any gravitationally supported parcel of gas. Definition A formal definition from the ''Glossary of Meteorology'' is: :The decrease of an atmospheric variable with height, the variable being temperature unless otherwise specified. Typically, the lapse rate is the negative of the rate of temperature change with altitude change: :\Gamma = -\frac where \Gamma (sometimes L) is the lapse rate given in units of temperature divided by units of altitude, ''T'' is temperature, and ''z'' is altitude. Convection and adiabatic expansion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Malaria
Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. Symptoms usually begin ten to fifteen days after being bitten by an infected mosquito. If not properly treated, people may have recurrences of the disease months later. In those who have recently survived an infection, reinfection usually causes milder symptoms. This partial resistance disappears over months to years if the person has no continuing exposure to malaria. Malaria is caused by single-celled microorganisms of the ''Plasmodium'' group. It is spread exclusively through bites of infected ''Anopheles'' mosquitoes. The mosquito bite introduces the parasites from the mosquito's saliva into a person's blood. The parasites travel to the liver where they mature and reproduce. Five species of ''Plasmodium'' can infect and be spread by h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ekman Spiral
The oceanic, wind driven Ekman spiral is the result of a force balance created by a shear stress force, Coriolis force and the water drag. This force balance gives a resulting current of the water different from the winds. In the ocean, there are two places where the Ekman spiral can be observed. At the surface of the ocean, the shear stress force corresponds with the wind stress force. At the bottom of the ocean, the shear stress force is created by friction with the ocean floor. This phenomenon was first observed at the surface by the Norwegian oceanographer Fridtjof Nansen during his Fram expedition. He noticed that icebergs did not drift in the same direction as the wind. His student, the Swedish oceanographer Vagn Walfrid Ekman, was the first person to physically explain this process. Bottom Ekman Spiral In order to derive the properties of an Ekman spiral a look is taken at a uniform, horizontal geostrophic interior flow in a homogeneous fluid. This flow will by denoted by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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