Some aspects of transition induced by freestream turbulence can be understood in terms of the continuous spectrum of the Orr-Sommerfeld and Squire equations. Instead of discrete mode (Tollmien-Schlichting wave) precursors, transition can be studied, starting from continuous mode precursors. An examination of mode shapes leads to a theory of how freestream disturbances penetrate the boundary lay...

An experimental investigation of the transition process in boundary layers subjected to forwardor aft-facing two-dimensional step excrescences is described. The objective of the work was to characterize the variation of transition Reynolds numbers with measurable roughness and boundary layer parameters, with the specific goal of specifying new tolerance criteria for laminar flow airfoils, along...

For some cases of diferrent boundary layer development conditions (roughness surface, turbulence in main flow) by adverse pressure gradient was determined tranzitiom region. Boundary Tranzition region found based on intermittency flow inside the layer. Intermitency evaluated using modiffied TERA method algorithm.

An examination of the effects of surface step excrescences on boundary layer transition was performed, using a unique experimental facility. The objective of the work was to characterize the variation of transition Reynolds numbers with measurable step size and boundary layer parameters, with the specific goal of specifying new tolerance criteria for laminar flow airfoils, alongside a fundament...

In geological storage of carbon dioxide (CO2), the buoyant CO2 plume eventually accumulates under the caprock. Due to interfacial tension between the CO2 phase and the water phase, a capillary transition zone develops in the plume. This zone contains supercritical CO2 as well as water with dissolved CO2. Under the plume, a diffusive boundary layer forms. We study how cross-flow between the capi...

Observations are presented to show that in an adverse pressure gradient boundary layer, beneath free-stream turbulence, the interaction between Klebanoff streaks and naturally arising instability waves leads to helical disturbances which break down to form turbulent spots. This occurs under low to moderate levels, 1%–2%, of free-stream turbulence. At high levels of free-stream turbulence, conve...

We investigate both the type I and II modes of stationary instability within the boundarylayer flow over a rotating disk. Extending the work of previous studies we find that the flow can be stabilised via the introduction of shear-thinning non-Newtonian fluids. Laminar-flow profiles are determined from a generalised von Kármán similarity solution. An asymptotic study is presented in the limit o...