New rheological model for the description of polymer foams

For engineering designing purposes it is of importance to understand the rheological behavior of foams. Neat polymer flow, which means non-Newtonian fluid flow, is described by models which require constant friction losses along a pipe. Hence, polymer foams provide no constant friction pressure drop along a pipe since pressure-dependent foam quality changes happen. In contrast to the already available quality-dependent correlations a density-related approach, named principle of Volume Equalizing is introduced. A Volume Equalized constitutive equation provides constant friction factors in pipe flow, even in the case when density changes because of foam compressibility. For the description of laminar flow in pipes with different foam qualities the Volume Equalized Power Law model fits very well measured data. At high flowing velocities the foams obey the phenomena of drag reduction. Using a specific Volume Equalized definition of Reynolds number it is possible to describe drag reducing foam flow regimes with the maximum drag reduction asymptote introduced for neat polymer solutions.

New rheological model for the description of polymer foams Academic Article