Binary supermassive black holes form naturally in galaxy mergers, but their long-term evolution is uncertain. In spherical galaxies, N-body simulations show that binary evolution stalls at separations much too large for significant emission of gravitational waves (the “final parsec problem”). Here, we follow the long-term evolution of a massive binary in more realistic, triaxial and rotating ga...

In this paper we develop globally stabilizing robust/disturbance rejection controllers for rotating stall and surge in axial flow compressors with uncertain system dynamics and exogenous disturbances. Specifically, using the nonlinearnonquadratic disturbance rejection optimal control framework for systems with bounded energy (square-integrable) L2 disturbances developed in [15] and the nonlinea...

Vertical axis wind turbine blades undergo dynamic stall due to the large 1 angle of attack variation they experience during a turbine rotation. Particle image 2 velocimetry on a pitching and surging airfoil was used to perform time resolved 3 measurements at blade Reynolds numbers near turbine operating conditions of 105. 4 These experiments were compared to simulations performed in the rotatin...

An unsteady two-dimensional finite-volume solver was developed based on Van Leer’s flux splitting algorithm in conjunction with “Monotonic Upstream Scheme for Conservation Laws (MUSCL)” limiters and the two-layer Baldwin-Lomax turbulence model was also implemented. To validate the solver, two test cases were prepared and the computed results had good agreements with reference data. The rotating...

The power requirement for a rotating parallel-disk assembly with through-flow is experimentally studied. The flow velocity at the test core exit is measured using a traverse hot-wire probe, from which the exit kinetic energy is determined. A traverse pitot tube is utilized to monitor the velocity distribution in the inlet duct from which the flow rate is evaluated. The total pressure characteri...

In this paper we analyze the problem of bifurcation con trol from a geometric perspective Our goal is to provide coordinate free geometric conditions under which con trol can be used to alter the bifurcation properties of a nonlinear control system These insights are expected to be useful in understanding the role that magnitude and rate limits play in bifurcation control as well as giving deep...