Fundamental Investigation into Spatio-Temporal Interactions on Bluff Bodies

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Focus Area: 
Energy Research
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Animation showing instantaneous vorticity distributions near the leading edge corner of a rectangular section. As the Reynolds number increases, the distance it takes for a Kelvin-Helmholtz vortex to form decreases. Additionally, the size of the vortex is

This project is acutely focused on the fundamental fluid physics governing the unsteady loads experienced by non-streamlined objects. Bluff bodies, as they are commonly known, experience abrupt separation of the flow which subjects them to the consequences of flows which may be unsteady and in many cases, transitioning from laminar towards turbulence. Examples of bluff bodies include tall buildings, bridge decks, and slung-load containers. One archetype geometry which has proven itself to be a benchmark for other studies is the rectangular prism. This work makes extensive use of the rectangular geometry, which is defined by its aspect ratio (L/h) along with more traditional aerodynamic parameters such as angle of attack, and Reynolds number, Re. The effort to understand and predict these loads is pursued primarily through experimental testing and analysis as well as a supplementary effort to apply linear stability methods where applicable.

Streamlines surrounding a 5:1 rectangular section. The angle of attack is 0 and 5 degrees respectively.

5:1 rectangle. Upper surface: Streamlines. Lower Half: Average spanwise vorticity is shown. Additionally, the inset image shows an instantaneous snap shot of vorticity showing the initial roll up of the shear layer into a Kelvin-Helmholtz vortex.

Time-averaged turbulent kinetic energy (TKE). The elevated levels of TKE on the 1:1 body are associated with the Von Kármán shedding whose influence is magnified when the mean flow does not re-attach before the trailing edge.