The Genesis of Eddies: Vortex-Induced Transitions in Laminar Pipe Flow

In this talk I will describe experiments where we inject streamwise vortices into laminar pipe flow. By tracking the flow field in 3D, we are able to observe the conversion of the laminar boundary layer into new vortex filaments, mediated by the injected vortices. This process is dependent on a number of factors such as the Reynolds number of the pipe flow, as well as the strength and location of the injected vortices. These results demonstrate how weak perturbations can seed the creation of new vortices in pipe flows near the turbulent transition.