Stream surfaces and stream volumes

A stream surface is similar to a streamline, but it does not start from a point, but from a line segment. The line segment moving with the flow will sweep along a surface depicting the flow well. As of now, this feature is not included in the application, due to the fact that there was no real need to display complex flows. Because of the Darcy assumption, there are no whirls or other higher-order phenomena. How stream surfaces can be used at best efficiency was described by Löffelman [4]. Stream volumes show what volume the material travelling with the flow would occupy. They are quite expensive to calculate; it usually includes tracing several particles and casting a surface around them. However, it is easy to notice that the pollutant transport calculation, which is quite expensive indeed, already have done the job. There is no real need for stream volumes, because adding a theoretical pollutant source and displaying the isosurface of the concentration does exactly the same.