Wave speed calculation for water hammer analysis

In order to accurately solve the water hammer problem using the Method of the Characteristics MOC is necessary to fulfil with the so-called Courant condition which establishes mandatorily that Cn = f(a) = 1 in each pipeline of the system, where a is the wave speed. The value of Cn is dependant of a...

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Autor principal:	Twyman,John
Lenguaje:	English
Publicado:	Universidad Católica de la Santísima Concepción 2016
Materias:	wave speed water hammer Courant number
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-28132016000200007
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spelling	oai:scielo:S0718-281320160002000072017-01-10Wave speed calculation for water hammer analysisTwyman,John wave speed water hammer Courant number In order to accurately solve the water hammer problem using the Method of the Characteristics MOC is necessary to fulfil with the so-called Courant condition which establishes mandatorily that Cn = f(a) = 1 in each pipeline of the system, where a is the wave speed. The value of Cn is dependant of a whose value depends in turn on the fluid properties (density, bulk modulus) and physical characteristics of each pipeline (elasticity modulus, diameter, wall thickness, supporting condition). Because water distribution systems usually has many different pipes, and therefore, many different wave speeds, it can be said that fulfil with Cn = 1 in each pipeline is a very difficult task, more when the solution by MOC needs a common time step At for all pipe sections of the system. A way of solution to this problem is applying the method of the wave-speed adjustment that involves modifying the value of a in each pipe section in a certain percentage up to obtain Cn = 1. With this procedure optimum results are guaranteed in numerical terms, but it is possible to say the same in physical terms? The question which arises is: what parameters within the formula of a must (or can) be changed without exceeding the characteristic values of the component material of the pipes?. This work shows that in some cases the wave speed modification can significantly alter the value of the parameters that define a, leading to values that can be physically inconsistent, fictitious or without practical application.info:eu-repo/semantics/openAccessUniversidad Católica de la Santísima ConcepciónObras y proyectos n.20 20162016-12-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-28132016000200007en10.4067/S0718-28132016000200007
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	wave speed water hammer Courant number
spellingShingle	wave speed water hammer Courant number Twyman,John Wave speed calculation for water hammer analysis
description	In order to accurately solve the water hammer problem using the Method of the Characteristics MOC is necessary to fulfil with the so-called Courant condition which establishes mandatorily that Cn = f(a) = 1 in each pipeline of the system, where a is the wave speed. The value of Cn is dependant of a whose value depends in turn on the fluid properties (density, bulk modulus) and physical characteristics of each pipeline (elasticity modulus, diameter, wall thickness, supporting condition). Because water distribution systems usually has many different pipes, and therefore, many different wave speeds, it can be said that fulfil with Cn = 1 in each pipeline is a very difficult task, more when the solution by MOC needs a common time step At for all pipe sections of the system. A way of solution to this problem is applying the method of the wave-speed adjustment that involves modifying the value of a in each pipe section in a certain percentage up to obtain Cn = 1. With this procedure optimum results are guaranteed in numerical terms, but it is possible to say the same in physical terms? The question which arises is: what parameters within the formula of a must (or can) be changed without exceeding the characteristic values of the component material of the pipes?. This work shows that in some cases the wave speed modification can significantly alter the value of the parameters that define a, leading to values that can be physically inconsistent, fictitious or without practical application.
author	Twyman,John
author_facet	Twyman,John
author_sort	Twyman,John
title	Wave speed calculation for water hammer analysis
title_short	Wave speed calculation for water hammer analysis
title_full	Wave speed calculation for water hammer analysis
title_fullStr	Wave speed calculation for water hammer analysis
title_full_unstemmed	Wave speed calculation for water hammer analysis
title_sort	wave speed calculation for water hammer analysis
publisher	Universidad Católica de la Santísima Concepción
publishDate	2016
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-28132016000200007
work_keys_str_mv	AT twymanjohn wavespeedcalculationforwaterhammeranalysis
_version_	1714203340025364480

Wave speed calculation for water hammer analysis

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