4 replies to this topic

[kasri]

Dear sir,
In dispersion studies, the terms crosswind and downwind are used.
What does it mean crosswind and downwind.Please clear my doubts.
Thanks & Regards,
Kasri

[djack77494]

Let's say that the wind is blowing from the North towards the South. If you are to the East or West of your emission source, then you are crosswind; if you are South of the source, then you are downwind; and if you are to the north of the source, then you are upwind.

[mbeychok]

kasri:

Look at the drawing of an air pollution plume in this article in the Citizendium online article:

Click here ==> Air pollution dispersion modeling

Any point on the x-axis is downwind of the source. Any point on the y-axis is crosswind of the source.

[Narnia]

I have to claculate the downwind & crosswind parameters for stack dispersion calculations, Can anybody guide me how to calculate these parameters. From a text book i have found below farmulas but these are not clear to me

Down wind = X = (X® - X(S)) sin(WD) - (Y® - Y(S)) cos(WD)
Cross wind = y = (X® - X(S)) cos(WD) - (Y® - Y(S)) sin(WD)

Waiting for very quick reply on this.
Thanks

[Narnia]

I have understood all the aparameters apart from WD (wind direction) how to insert its value in the above mentioned farmula.

thanks