Abstract:
Although it is a well-known fact that dilute solutions obtained by adding a small amount of polymer or surfactant to Newtonian fluids lead to a reduction in friction factor and drag coefficient at high Reynolds number flows; its mechanism and the polymer induced flow structure at high Reynolds numbers need to be investigated in more detail for different flow geometries by means of new experimental methods, as well as numerical simulations with the application of different rheological constitutive models. For clarification of such an important part of fluid mechanics, numerical simulations have been performed with Newtonian, generalized Newtonian (Power-law) and viscoelastic (FENE-P) fluid models, Reynolds number up to 4000 for circular cylinder domain and Reynolds number up to 2000 for square cylinder domain. The results of the simulations have been compared with literature. The most distinctive consequences of these simulations is that Power-law fluid, not the viscoelastic fluid, causes decrease in drag coefficient and increase in vortex shedding frequency in the wake region compared to Newtonian fluid, for both circular and square cylinder simulations. It is also concluded that polymer addition, with respect to Power-law fluid, results in an opposite effect, on vortex formation length and drag coefficient, at high Reynolds numbers.
