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Depending on the source there is a range mentioned of 0.1<Kn<10 for which Knudsen flow occurs. Other names for this flow regime are intermediate, transitional, or slip flow, since it represents a transition state between free molecular flow and viscous flow. Thus the flow of fluids under Knudsen flow conditions is established both by molecular ...
A simplified version of the definition is: The k v factor of a valve indicates "The water flow in m 3 /h, at a pressure drop across the valve of 1 kgf/cm 2 when the valve is completely open. The complete definition also says that the flow medium must have a density of 1000 kg/m 3 and a kinematic viscosity of 10 −6 m 2 /s, e.g. water. [clarify]
In hypersonic flow, the pressure coefficient can be accurately calculated for a vehicle using Newton's corpuscular theory of fluid motion, which is inaccurate for low-speed flow and relies on three assumptions: [5] The flow can be modeled as a stream of particles in rectilinear motion; Upon impact with a surface, all normal momentum is lost
A flow that is not a function of time is called steady flow. Steady-state flow refers to the condition where the fluid properties at a point in the system do not change over time. Time dependent flow is known as unsteady (also called transient [8]). Whether a particular flow is steady or unsteady, can depend on the chosen frame of reference.
The Knudsen number is a dimensionless number defined as =, where = mean free path [L 1], = representative physical length scale [L 1].. The representative length scale considered, , may correspond to various physical traits of a system, but most commonly relates to a gap length over which thermal transport or mass transport occurs through a gas phase.
Uniform flow. The depth of flow is the same at every section of the channel. Uniform flow can be steady or unsteady, depending on whether or not the depth changes with time, (although unsteady uniform flow is rare). Varied flow. The depth of flow changes along the length of the channel. Varied flow technically may be either steady or unsteady.
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u is the flow speed in m/s. It can be thought of as the fluid's kinetic energy per unit volume. For incompressible flow, the dynamic pressure of a fluid is the difference between its total pressure and static pressure. From Bernoulli's law, dynamic pressure is given by =