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Capillary action of water (polar) compared to mercury (non-polar), in each case with respect to a polar surface such as glass (≡Si–OH). Capillary action (sometimes called capillarity, capillary motion, capillary rise, capillary effect, or wicking) is the process of a liquid flowing in a narrow space without the assistance of external forces like gravity.
Paper towels absorb water because they are extremely absorbent, which enables water to travel into the fibers, even against gravity (capillary effect). They have similar purposes to conventional towels, such as drying hands, wiping windows and other surfaces, dusting, and cleaning up spills.
For velocities and pipe diameters above a threshold, actual fluid flow is not laminar but turbulent, leading to larger pressure drops than calculated by the Hagen–Poiseuille equation. Poiseuille's equation describes the pressure drop due to the viscosity of the fluid; other types of pressure drops may still occur in a fluid (see a ...
r = radius of the pipe (for a pipe of circular section, the internal radius of the pipe). v = mean velocity of fluid flowing through the pipe. A = cross sectional area of the pipe. In long pipes, the loss in pressure (assuming the pipe is level) is proportional to the length of pipe involved.
In fluid mechanics, pipe flow is a type of fluid flow within a closed conduit, such as a pipe, duct or tube. It is also called as Internal flow. [1] The other type of flow within a conduit is open channel flow. These two types of flow are similar in many ways, but differ in one important aspect.
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 ...
Barlow's formula (called "Kesselformel" [1] in German) relates the internal pressure that a pipe [2] can withstand to its dimensions and the strength of its material.. This approximate formula is named after Peter Barlow, an English mathematician.
Pressure in water and air. Pascal's law applies for fluids. Pascal's principle is defined as: A change in pressure at any point in an enclosed incompressible fluid at rest is transmitted equally and undiminished to all points in all directions throughout the fluid, and the force due to the pressure acts at right angles to the enclosing walls.