Influence of polymer additive on flow past a hydrofoil: A numerical study

Abstract

Flows of dilute polymer solutions past a hydrofoil (NACA0012) are examined by direct numerical simulation to investigate the modification of the wake pattern due to the addition of polymer. The influence of polymer additive is modeled by the FENE-P model in order to simulate a non-linear modulus of elasticity and a finite extendibility of the polymer macromolecules. Simulations were carried out at a Reynolds number of 1000 with the angle of attack varying from 0° to 20°. The results show that the influence of polymer on the flow behavior of the flow past a hydrofoil exhibits different flow regimes. In general, the addition of polymer modifies the wake patterns for all angles of attack in this study. Consequently, both drag and lift forces are changed as the Weissenberg number increases while the drag of the hydrofoil is enhanced at small angles of attack and reduced at large angles of attack. As the Weissenberg number increases, two attached recirculation bubbles or two columns of shedding vortices downstream tend to be symmetric, and the polymer tends to make the flow less sensitive to the variation of the angle of attack.

Contribution of Superhydrophobic Surfaces and Polymer Additives to Drag Reduction

“…investigated turbulent DR and analyzed the molecular stretching characteristic by using the viscoelastic Oldroyd‐B model in a channel. Results were interpreted by proposing that polymer molecules absorb elastic energy near the wall and then were transported and dissipated into the buffer layer which minimizes the vortices 8, 137–140. Polymer extensibility shows a more complicated influence in turbulent flows for confined geometries and over bluff bodies.…”

Direct Numerical Simulations on the three-dimensional wake transition of flows over NACA0012 airfoil at Re = 1000

“…For benchmark, present results of mean coefficients of drag (Cd) and lift (Cl) with data presented in previous works are illustrated in Figure 2(a) and 2(b) respectively and found to be in good agreement with literature. 3,[26][27][28] Three-dimensional mesh is constructed by extruding 2D geometry in z-direction, resulting in identical mesh of same resolution in all the planes normal to the spanwise direction. Cell size (Δz) = 0.08c is considered in spanwise direction.…”

“…Furthermore, there are plenty of studies on the experimental and numerical study at such Re for comparison. 3,4,[26][27][28] One may expect that flow behavior with closed Reynolds number is similar but with variant critical angles of attack.…”