Vortex dynamics of accelerated flow past a mounted wedge

TL;DR

This paper presents a high-fidelity numerical simulation of flow past a wedge at various Reynolds numbers, capturing vortex shedding and transition to turbulence, validated against experimental data and exploring effects of acceleration.

Contribution

The study introduces a second-order compact finite difference method for simulating complex accelerated flows past a wedge, extending simulation duration and capturing detailed vortex dynamics.

Findings

Accurately reproduces experimental flow features and vortex shedding patterns.

Demonstrates the influence of acceleration parameter on flow instability.

Captures transition to turbulence and complex vortex structures.

Abstract

This study is concerned with the simulation of a complex fluid flow problem involving flow past a wedge mounted on a wall for channel Reynolds numbers $Re_c=1560$, $6621$ and $6873$ in uniform and accelerated flow medium. The transient Navier-Stokes (N-S) equations governing the flow has been discretized using a recently developed second order spatially and temporally accurate compact finite difference method on a nonuniform Cartesian grid by the authors. All the flow characteristics of a well-known laboratory experiment of Pullin and Perry (1980) have been remarkably well captured by our numerical simulation, and we provide a qualitative and quantitative assessment of the same. Furthermore, the influence of the parameter $m$, controlling the intensity of acceleration, has been discussed in detail along with the intriguing consequence of non-dimensionalization of the N-S equations pertaining to such flows. The simulation of the flow across a time span significantly greater than the aforesaid lab experiment is the current study's most noteworthy accomplishment. For the accelerated flow, the onset of shear layer instability leading to a more complicated flow towards transition to turbulence have also been aptly resolved. The existence of coherent structures in the flow validates the quality of our simulation, as does the remarkable similarity of our simulation to the high Reynolds number experimental results of Lian and Huang (1989) for the accelerated flow across a typical flat plate. All three steps of vortex shedding, including the exceedingly intricate three-fold structure, have been captured quite efficiently.