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Outfall data:

An outfall is a pollutant point source. The outfall is small if we compare it with the size of the area in which we are simulating (point source). If you click this button, the next dialog box is shown:

Depending on the used model, some data of the dialog box can be modified: Buoyant jet model or Stratified model (see calculation models).

Buoyant jet model: The necessary data in the Buoyant jet model is:

Effluent velocity u_a (m/s): The average velocity of the pollutant effluent. It can be around 1 m/s.

Pollutant concentration (g/m³): The discharge concentration of the material of interest (pollutant or tracer) is defined as the excess concentration above any ambient concentration of that same material. 1g/m³=1ppm in water.

Water depth at discharge location (m): The actual water depth at the sumerged discharge location. For surface discharges it is the water depth at the channel entry location.

Discharge flow rate (m³/s): The discharge flow rate and the discharge velocity are related through the port cross-sectional area. (Flow rate)=(area)x(discharge velocity).

Discharge density (kg/m³): It is the density of the pollutant discharge.

Discharge conditions: There are three options: Vertical discharge, Horizontal discharge (A-type) and Horizontal discharge (B-type). In the vertical discharge, the discharge flow is perpendicular to the water surface. In the horizontal discharges (A and B), the discharge flow is parallel to the water surface. In the horizontal discharge case, we assume that the discharge vector is always perpendicular to current vector. That is to simplify the calculations. In the A-type, the flow vector points the South and the current vector points the East. In the B-type, the flow vector points the North and the current vector points the East.

Stratified model: The necessary data in the Stratified model is:

Pipe angle (0 to 360): It is the horizontal angle of discharge measured clockwise from the North (at the window top).

Diffusor length (m): The diffuser length is the distance from the first to the last port or nozzle.

1/T90 (1/horas): This coefficient considers the half life of the pollutant if this disappears by means of chemical reactions (non-conservative pollutant). This is the T90 for E.Coli. For towns with less than 10.000 inhabitants we can take a T90=2 hours (1/T90=0,5 hours^-1) in the Mediterranean and T90=3 hours (1/T90=0,33 hours^-1) in the Atlantic.

Important note for DESCAR 3.1 (or lower versions):

In the approved model, T90 is un hours (this is used by the program). However, and in equation F₀(t)=10^-t/T90  of the approved model(1), time must be in seconds . Following criteria of mathematical coherence and results T90 must be expressed in seconds (multiply by 3600 seconds in one hour). At this point, the user can work following two different ways: using the approved model as is or rectify in the T90 input data. For example, for a T90=2 hours value, the user can introduce as input data:

(a) Following the approved model:

1/T90=0.5 hours^-1 as input data. Then, write 0.5 in the window textbox for a T90=2 hours value .

(b) Following criteria of mathematical coherence and results:

1/T90=1/(2 x 3600)=0,000278 as input data. Then, write 0,000278 in the window textbox for a T90=2 hours value.

(1) Orden del 13 de Julio de 1993 del Ministerio de Obras Públicas y Transportes del Reino de ESPAÑA, B.O.E. Martes 27 de Julio de 1993, página 22861.

Number of openings: DESCAR allows for different types of discharge geometries. There are three options: Single port, Multiport diffuser and Separated ports.  We have a multiport diffuser when the separation among the ports is less than 3% of the depth. We have Separated ports when the separation among the ports is bigger than 20% of the water depth.

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DESCAR - Solutions - Advantages - Price - Data I - Data II - Average - Import - Graphs I - Graphs II  -  Commands - Algorithms I - Algorithms II - Algorithms III - Algorithms IV - Algorithms V - Algorithms VI - Algorithms VII - Pollutants I - Pollutants II - The sea I - The sea II - Pycnocline - Google maps - GIS

 

 

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