virtaalueen
Virta-alueen (flow area) on termi used in fluid mechanics to denote the cross-sectional area through which a fluid passes at a specific location along its path. It is defined as the area perpendicular to the local flow direction and is a key parameter for describing discharge and velocity in pipes, channels, and other conduits. In Finnish texts the term may appear as virta-alue or virta-alueen in different grammatical forms.
In the simplest form, the discharge Q is related to the flow area by the continuity equation.
Applications of virta-alueen appear in hydraulics, piping, and open-channel flow. A reduction in the cross‑sectional area
Note that in Finnish hydrology the term valuma-alue refers to a catchment or drainage basin, which is