Viscoelastic flow behavior and formation of dead zone around triangle-shaped pillar array in microchannel

Effect of viscoelasticity on displacement processes in porous media

“…The primary importance of shear flow has also been confirmed in other works, where it has been demonstrated that the normal stress differences responsible for an increased pressure gradient are mainly generated in shear dominated regions De et al [52]; Ekanem et al [54], and most of the energy of viscoelastic stresses is dissipated in these regions De et al [86]; Gillissen [53]. In summary, the elastic nature of the polymer fluid is more pronounced when coupled with the extensional nature of the flow field Kawale et al [37]; Walkama et al [51]; Haward et al [50]; Ichikawa and Motosuke [49], however extensional flow is not essential to observe elasticity-induced flow instabilities. In fact, the most important feature is tortuosity, i.e., curved path lines that cause a sufficiently strong first normal stress difference of viscoelastic fluids.…”

“…To address these issues, microfluidic model systems raised interest among researchers Galindo-Rosales et al [42]; Browne et al [43]; Kumar et al [44]. Several experimental and numerical studies have been focused on basic designs representing simplified porous media such as straight channels embedded with single cylinders Hemingway et al [45]; Qin and Arratia [46]; Qin et al [47], uniform or random post arrays Khomami and Moreno [48]; Ichikawa and Motosuke [49]; Haward et al [50]; Walkama et al [51], a single pore formed by four disks De et al [52]; Gillissen [53], and converging-diverging channels Ekanem et al [54]; Galindo-Rosales et al [55]; Kumar et al [56]; Ekanem et al [57]. However, even in the simplest designs used so far, description of viscoelastic flow is still very complex due to a wide distribution of flow velocity (and consequently shear rate) caused by the non-constant cross-section of flow pathways in these geometries.…”