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Prognostic Equation
Prognostic equation - in the context of physical (and especially geophysical) simulation, a prognostic equation predicts the value of variables for some time in the future on the basis of the values at the current or previous times. For instance, the well-known Navier-Stokes equations that describe the time evolution of a fluid are prognostic equations that predict the future distribution of velocities in that fluid on the basis of current fields such as the pressure gradient. See also *diagnostic equation In a physical (and especially geophysical) simulation context, a diagnostic equation (or diagnostic model) is an equation (or model) that links the values of these variables simultaneously, either because the equation (or model) is time-independent, ... References James R. Holton (2004) ''An Introduction to Dynamic Meteorology'', Academic Press, International Geophysics Series Volume 88, Fourth Edition, 535 p., , {{ISBN, 978-0-12-354015-7. See also http://glossary.ametsoc. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressure Gradient
In atmospheric science, the pressure gradient (typically of Earth's atmosphere, air but more generally of any fluid) is a physical quantity that describes in which direction and at what rate the pressure increases the most rapidly around a particular location. The pressure gradient is a dimensional quantity expressed in units of pascal (unit), pascals per metre (Pa/m). Mathematically, it is the gradient of pressure as a function of position. The negative gradient of pressure is known as the force density. In petroleum geology and the petrochemical sciences pertaining to oil wells, and more specifically within hydrostatics, pressure gradients refer to the gradient of vertical pressure in a column of fluid within a wellbore and are generally expressed in pounds per square inch per foot (unit), foot (psi/ft). This column of fluid is subject to the compound pressure gradient of the overlying fluids. The path and geometry of the column is totally irrelevant; only the vertical depth of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diagnostic Equation
In a physical (and especially geophysical) simulation context, a diagnostic equation (or diagnostic model) is an equation (or model) that links the values of these variables simultaneously, either because the equation (or model) is time-independent, or because the variables all refer to the values they have at the identical time. This is by opposition to a prognostic equation. For instance, the so-called ideal gas law (''PV'' = ''nRT'') of classical thermodynamics relates the state variable A state variable is one of the set of variables that are used to describe the mathematical "state" of a dynamical system. Intuitively, the state of a system describes enough about the system to determine its future behaviour in the absence of a ...s of that gas, all estimated at the same time. It is understood that the values of any one of these variables can change in time, but the relation between these variables will remain valid at each and every particular instant, which implies that one ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |