Significance of the strain-dominated region around a vortex on induced aerodynamic loads

The ability of vortices to induce aerodynamic loads on proximal surfaces plays a significant role in a wide variety of flows. However, most studies of vortex-induced effects primarily focus on analysing the influence of the rotation-dominated cores of vortices. In this work, we show that not only are vortices in viscous flows surrounded by strain-dominated regions, but these regions are dynamically important and can sometimes even dictate the induced aerodynamic loads. We demonstrate this for a pitching airfoil, which exhibits dynamic stall and generates several force-inducing vortices. Using a data-driven force partitioning method (FPM), we quantify the influence of vortices as well as vortex-associated strain to show that our current understanding of vortex-dominated phenomena, such as dynamic stall, is incomplete without considering the substantial effect of strain-dominated regions that are associated with vortices.

Automated summary

This study reveals the presence of strain-dominated regions surrounding vortices in viscous flows, which are dynamically important and may even determine the induced aerodynamic loads. By analyzing a pitching airfoil case with dynamic stall and force-inducing vortices, it is shown that the current understanding of vortex-dominated phenomena is incomplete without considering the substantial effect of strain-dominated regions associated with vortices.