<unk>  is a method of<unk>  and<unk>  various flows using dye as a flow tracer when added to a liquid.<unk>  may be used to analyse the flow of the liquid or the transport of objects within the liquid.<unk>  may be either qualitative, showing the presence of a particular flow, or quantitative, when the amount of the traced dye is measured by special instruments.
Dye tracing
Double dye test
Biotelemetry
Intravascular fluorescence
Foerster clamp
Doppler 
Entropy monitoring
Thorpe tube flowmeter