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# Surge Analysis

Joukowsky Equation

The Joukowsky equation is a method of determining the surge pressures that will be experienced in a fluid piping system. When a fluid in motion is forced to either stop or change direction suddenly a pressure wave will be generated and propagated through the fluid. This pressure wave is commonly referred to as fluid hammer (also known as water hammer, surge or hydraulic shock) and typically occurs in piping systems when a valve is suddenly closed, isolating the line. The resultant surge pressures are complex to characterise but for simple systems they may be calculated using the Joukowsky equation.

Mach Number

The Mach number is the ratio of the relative velocity of a fluid to the local speed of sound. This article provides the equation for the calculation of the Mach number and a discussion of its uses.

Speed of Sound in Fluids and Fluid in Pipes

This article provides the formulae for the calculation of speed of sound in fluids and fluid filled circular pipes. The speed of sounds is important in piping systems for the calculation of choked flow for gases and pressure transient analysis of liquid filled systems.

Bulk Modulus of Elasticity of Liquids

The bulk modulus or elasticity is a measure of the resistance to compression of a substance. This article presents the bulk modulus for various liquids.