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The peak expiratory flow (PEF), also called peak expiratory flow rate (PEFR) and peak flow measurement, [1] is a person's maximum speed of expiration, as measured with a peak flow meter, a small, hand-held device used to monitor a person's ability to breathe out air.
In hydrology, discharge is the volumetric flow rate (volume per time, in units of m 3 /h or ft 3 /h) of a stream. It equals the product of average flow velocity (with dimension of length per time, in m/h or ft/h) and the cross-sectional area (in m 2 or ft 2). [1] It includes any suspended solids (e.g. sediment), dissolved chemicals like CaCO
MMEF or MEF stands for maximal (mid-)expiratory flow and is the peak of expiratory flow as taken from the flow-volume curve and measured in liters per second. It should theoretically be identical to peak expiratory flow (PEF), which is, however, generally measured by a peak flow meter and given in liters per minute. [16]
The maximum instantaneous flow achieved during a FVC maneuver: FIF: Forced inspiratory flow: (Specific measurement of the forced inspiratory curve is denoted by nomenclature analogous to that for the forced expiratory curve. For example, maximum inspiratory flow is denoted FIF max. Unless otherwise specified, volume qualifiers indicate the ...
For example, maximum inspiratory flow is denoted FIF max. Unless otherwise specified, volume qualifiers indicate the volume inspired from RV at the point of measurement.) PEF: Peak expiratory flow: The highest forced expiratory flow measured with a peak flow meter: MVV
In hypersonic flow, the pressure coefficient can be accurately calculated for a vehicle using Newton's corpuscular theory of fluid motion, which is inaccurate for low-speed flow and relies on three assumptions: [5] The flow can be modeled as a stream of particles in rectilinear motion; Upon impact with a surface, all normal momentum is lost
laminar flow occurs at low Reynolds numbers, where viscous forces are dominant, and is characterized by smooth, constant fluid motion; turbulent flow occurs at high Reynolds numbers and is dominated by inertial forces, which tend to produce chaotic eddies, vortices and other flow instabilities. [8] The Reynolds number is defined as: [4]
The flow coefficient of a device is a relative measure of its efficiency at allowing fluid flow. It describes the relationship between the pressure drop across an orifice valve or other assembly and the corresponding flow rate. Mathematically the flow coefficient C v (or flow-capacity rating of valve) can be expressed as