Aviation

Four Eulerian network models are implemented to model high altitude air traffic flow. Three of the models use the framework of discrete time dynamical systems, while the fourth consists of a network of partial differential equations. The construction of these models is done using one year of air traffic data. The four models are applied to high altitude traffic for six Air Route Traffic Control Centers in the National Airspace System and surrounding airspace. Simulations are carried out for a full day of data for each of the models, to assess their predictive capabilities. The models’...

The problem of regulating air traffic in the en route airspace of the National Airspace System is studied using a Eulerian network model to describe air traffic flow. The evolution of traffic on each edge of the network is modeled by a modified Lighthill-Whitham-Richards partial differential equation. The equation is transformed with a variable change, which makes it linear and enables us to use linear finite difference schemes to discretize the problem. We pose the problem of optimal traffic flow regulation as a continuous optimization program in which the partial differential equation...

The understanding and identification of the physical instability mechanisms responsible for the appearance of unsteadiness and three-dimensionality on laminar separation bubbles can provide a fundamental insight into the aerodynamic characteristics of airfoils at stall conditions, and guide the development of strategies for the control of separated flows. Separation bubbles have been demonstrated to have an intrinsic instability mechanism, which results in the appearance of spanwise-periodic three-dimensional structures. The instability mechanism responsible for three-dimensionality was...

Several studies spanning since the 1970s to the present, considering turbulent flows at realistic conditions for aircraft flight, have amassed evidence on the dominance of a far-field tonal noise, usually associated with vortex-shedding from the trailing edge. Furthermore, the appearance of multiple tones has been documented for increasing values of the angle of attack and Mach number, which exhibit a ladder-like pattern in terms of the variation of the frequencies with increasing free-stream velocity. Different explanations have been suggested for the origin of the (i) single tone, (ii)...