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In fluid dynamics, head is a concept that relates the energy in an incompressible fluid to the height of an equivalent static column of that fluid. From Bernoulli's principle, the total energy at a given point in a fluid is the kinetic energy associated with the speed of flow of the fluid, plus energy from static pressure in the fluid, plus energy from the height of the fluid relative to an ...
A head's location varies with the height of the water level against the dam. Since there is only an extremely low flow within the reservoir so no water level gradient, the head can be clearly seen: where the farthest watercourse discharges into the reservoir.
Hydraulic head (red line) gradients actually cause groundwater to flow. Pressure head (blue line) is zero at the top of the column, as designated by the inverted triangle and horizontal lines (showing the water table). Elevation head (green line) always increases 1:1 with elevation.
h = z + p / ρg is the piezometric head or hydraulic head (the sum of the elevation z and the pressure head) [11] [12] and; p 0 = p + q is the stagnation pressure (the sum of the static pressure p and dynamic pressure q). [13] The constant in the Bernoulli equation can be normalized.
Hydraulic head is composed of pressure head (ψ) and elevation head (z). The head gradient is the change in hydraulic head per length of flowpath, and appears in Darcy's law as being proportional to the discharge.
Any body of arbitrary shape which is immersed, partly or fully, in a fluid will experience the action of a net force in the opposite direction of the local pressure gradient. If this pressure gradient arises from gravity, the net force is in the vertical direction opposite that of the gravitational force.
It takes energy to push a fluid through a pipe, and Antoine de Chézy discovered that the hydraulic head loss was proportional to the velocity squared. [5] Consequently, the Chézy formula relates hydraulic slope S (head loss per unit length) to the fluid velocity V and hydraulic radius R :
R h is the hydraulic radius (L; ft, m); S is the stream slope or hydraulic gradient, the linear hydraulic head loss loss (dimension of L/L, units of m/m or ft/ft); it is the same as the channel bed slope when the water depth is constant. (S = h f /L). k is a conversion factor between SI and English units.