Viscoelastic Flows in Abrupt Contraction - Expansions

IV. Pressure Drop Definition In our experiments we measure the total pressure drop across the axisymmetric abrupt contraction-expansion geometry. We then systematically correct this to report an ‘extra pressure drop’ associated with the contraction-expansion alone. Table 1 shows the axial distance of each possible pressure transducer location from the contraction plane. For clarity, it is useful to define several differential pressures by the location of the pressure transducers used. For instance, the pressure drop across the contraction-expansion measured between pressure transducers 2 and 4 is denoted as P24 = (P2 ! P4). Several different pressure transducers locations were created sufficiently far upstream of the contraction plane to ensure that the pressure transducers were not affected by the presence of the elastically-driven growth of the upstream (and downstream) vortices. In the subsequent measurements only the upstream pressure transducer at location P2 was used.