# Evidence for Vortex Shedding in the Sun's Hot Corona

## TL;DR

This paper presents observational evidence of vortex shedding in the Sun's hot corona, linking plasma flow oscillations to MHD phenomena and confirming simulation predictions through Strouhal number analysis.

## Contribution

It provides the first observational evidence of vortex shedding in the solar corona, connecting theoretical MHD simulations with actual solar plasma behavior.

## Key findings

- Detected oscillating plasma flow in the solar corona.
- Computed Strouhal number consistent with MHD simulations.
- Suggests vortex shedding occurs in the solar corona.

## Abstract

Vortex shedding is an oscillating flow that is commonly observed in fluids due to the presence of a blunt body in a flowing medium. Numerical simulations have shown that the phenomenon of vortex shedding could also develop in the magnetohydrodynamic (MHD) domain. The dimensionless Strouhal number, the ratio of the blunt body diameter to the product of the period of vortex shedding and the speed of a flowing medium, is a robust indicator for vortex shedding, and, generally of the order of 0.2 for a wide range of Reynolds number. Using an observation from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, we report a wavelike or oscillating plasma flow propagating upward against the Sun's gravitational force. A newly formed shrinking loop in the post-flare region possibly generates the oscillation of the upflow in the wake of the hot and dense loop through vortex shedding. The computed Strouhal number is consistent with the prediction from previous MHD simulations. Our observation suggests the possibility of vortex shedding in the solar corona.