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The pressure gradient is defined only at these spatial scales at which pressure (more generally fluid dynamics) itself is defined. Within planetary atmospheres (including the Earth's ), the pressure gradient is a vector pointing roughly downwards, because the pressure changes most rapidly vertically, increasing downwards (see vertical pressure ...
Turbulent boundary layers tend to be able to sustain an adverse pressure gradient better than an equivalent laminar boundary layer. The more efficient mixing which occurs in a turbulent boundary layer transports kinetic energy from the edge of the boundary layer to the low- momentum flow at the solid surface, often preventing the separation ...
In fluid mechanics, the pressure-gradient force is the force that results when there is a difference in pressure across a surface. In general, a pressure is a force per unit area across a surface. A difference in pressure across a surface then implies a difference in force, which can result in an acceleration according to Newton's second law of ...
Gradients are expressed as a ratio of vertical rise to horizontal distance; for example, a 1% gradient (1 in 100) means the track rises 1 vertical unit for every 100 horizontal units. On such a gradient, a locomotive can pull half (or less) of the load that it can pull on level track.
The Coriolis force acts at right angles to the flow, and when it balances the pressure gradient force, the resulting flow is known as geostrophic. As stated above, the direction of flow is with the high pressure to the right of the flow in the Northern Hemisphere, and the high pressure to the left in the Southern Hemisphere. The direction of ...
In the limit of infinite Reynolds number, the pressure gradient term can be shown to have no effect on the inner region of the turbulent boundary layer. The new "inner length scale" η {\displaystyle \eta } is a viscous length scale, and is of order ν u ∗ {\displaystyle {\frac {\nu }{u_{*}}}} , with u ∗ {\displaystyle u_{*}} being the ...
The pressure gradient term (c) describes how pressure changes with position, and since the pressure is assumed hydrostatic, this is the change in head over position. The friction term (d) accounts for losses in energy due to friction, while the gravity term (e) is the acceleration due to bed slope.
Trees showing the presence of creep. Downhill creep, also known as soil creep or commonly just creep, is a type of creep characterized by the slow, downward progression of rock and soil down a low grade slope; it can also refer to slow deformation of such materials as a result of prolonged pressure and stress.