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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 ...
The horizontal pressure gradient is a two-dimensional vector resulting from the projection of the pressure gradient onto a local horizontal plane. Near the Earth's surface, this horizontal pressure gradient force is directed from higher toward lower pressure. Its particular orientation at any one time and place depends strongly on the weather ...
The pressure force pushing the liquid through the tube is the change in pressure multiplied by the area: F = −A Δp. This force is in the direction of the motion of the liquid. The negative sign comes from the conventional way we define Δp = p end − p top < 0. Viscosity effects will pull from the faster lamina immediately closer to the ...
Flux F through a surface, dS is the differential vector area element, n is the unit normal to the surface. Left: No flux passes in the surface, the maximum amount flows normal to the surface.
Vertical pressure variation is the variation in pressure as a function of elevation.Depending on the fluid in question and the context being referred to, it may also vary significantly in dimensions perpendicular to elevation as well, and these variations have relevance in the context of pressure gradient force and its effects.
The change in pressure over distance dx is dp and flow velocity v = dx / dt . Apply Newton's second law of motion (force = mass × acceleration) and recognizing that the effective force on the parcel of fluid is −A dp. If the pressure decreases along the length of the pipe, dp is negative but the force resulting in flow is positive ...
The pressure gradient can be positive (adverse pressure gradient) or negative (favorable pressure gradient). In the limiting case of stationary plates ( U = 0 {\displaystyle U=0} ), the flow is referred to as Plane Poiseuille flow , and has a symmetric (with reference to the horizontal mid-plane) parabolic velocity profile.
The pressure gradient force causes an acceleration forcing air from regions of high pressure to regions of low pressure. Mathematically, this can be written as: =. The gravitational force accelerates objects at approximately 9.8 m/s 2 directly towards the center of the Earth.