A = 2r2 sinl(a)-aAx (2.9)
r
R = 2 (2.10)
)Tr
A = q 2r [v q= (2.11)
RO 0
where
a= [r2 -( )2 (2.12)
r = radius of the device
If 4, is the dimensionless cumulative volume of fluid conveyed through the
device, then equation 2.10 can also be stated as
mR [sin 1 2)- 2] (2.13)
qAt
= (2.14)
20Rr
However, due to the circular cross section only at the very beginning is the tracer
present over the whole width of the device (2r). As the tracer is desorbed, some water
will pass the device without leaching out any of the tracer. The distance "a" from the
center, this is equal to the radius of the section at the beginning. This also decreases with
growing Ax and the water passing the device at distances greater than "a" from the center
does not leach out tracer any more. Therefore, equation 2.13 must be used to describe the
relation between the relative remaining tracer mass mR and the dimensionless cumulative
volume 4. To simplify equation 2.13, Klammler (2001) performed regression analysis for
the variation of with mR and observed that regression equation is almost linear for less