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DESCAR software: algorithms II

                               

 

1. Buoyant jet model

A type of mathematical model that has been developed for sumerged round buoyant jets is the length-scale model.  Discharges flows can be divided into different regimes each dominated by particular flow properties. Within each regime, the flow may be approximated with simple mathematical relations describing the simplified problem. A model that uses asymptotic solutions is refered to as length-scale model because of length scales to delineate the extent of the regimes for which the mathematical expressions are valid. The pollutant concentration, in a certain instant, and at a distance x (meters) in the X-Axis and at a distance y(meters) in the Y-Axis will be given by: 

 

c =cc exp[-(r/b)2]  (1)

 

where c is the pollutant concentration, r is the distance from the point (that we are calculating) to the center of the line that forms the polluting plume, cc is the pollutant concentration in the center of the plume line and b is the plume half-width. We attempt to link the momentum dominated and buoyanvy dominated regimes into one relationship by using proposed relations for the transition where: 

 

z/Lb =24/3[(1/2)(x/Lb)2+(Lm/Lb)(x/Lb)]1/3  (2)

b/Lb =cb[(1/2)(x/Lb)2+(Lm/Lb)(x/Lb)]1/3    (3)

S=cs(uo/ua)[(1/2)(Lb/Lm)(x/Lm)2+(x/Lm)]1/3 (4)

Lb=plume-to-crossflow length scale

Lm=jet-to-crossflow length scale

x=horizontal downstream coordinate in global coordinate system

y=horizontal coordinate in coordinate system perpendicular to ambient crossflow

z=vertical coordinate

ua=ambient velocity

uo=discharge velocity

S=dilution along the plume centerline C/C0 being C the centerline pollutant concentration and the C0 initial pollutant concentration at the discharge.

cb=constant of proportionality that can be modified by the user (can be determined experimentally)

cs=constant of proportionality that can be modified by the user (can be determined experimentally)

cxy=constant of proportionality that can be modified by the user (can be determined experimentally)

We obtain solutions for a vertical buoyant jet in a crossflow. And buoyant jets discharged horizontally perpendiculat to crossflow.

z/Lb =cxy(x/Lm)1/3    (5) 

 

This model performs satisfactorily for simple flows with no shoreline interaction or attachment. Strong crosscurrents or limited depths causing attachment with the downstrean bank or strong initial buoyancy render this model invalid. In addition, they are incapable of simulating any far-field processes that occur after a certain distance.

 

 

 

Algorithms I -  Algorithms II - Algorithms III - Algorithms IV - Algorithms V - Algorithms VI - Algorithms VII

 

                                                                               

Canarina Algoritmos Numéricos, S.L.

Environmental software · environmental software solutions

Canary Islands, Spain

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European Union · network on Pollution

Member of MAPO: European network on Marine Pollution.

Project funded by the European Commission

through the 6th Framework Programme for Research and Development

 

 

                               

 

DESCAR: water pollution - Solutions - Advantages - Price - Data I - Data II - Advantages - Temporal average - Import - Commands - Graphs I - Graphs II - Algorithms I -  Algorithms II - Algorithms III - Algorithms IV - Algorithms V - Algorithms VI - Algorithms VII - Pollutants I - Pollutants II - The sea I - The sea II - Google maps - GIS

Copyright © 2005 Canarina Algoritmos Numéricos, Sociedad Limitada Unipersonal CIF-B38803110 registered for electronic commerce in sheet TF-35526, sheet 1 of the volume 2.671 of the General Section, First Registration, Registro de la Propiedad Número 2 y Marcantil of , Spain. All rights reserved.