Inertial waves and small-scale turbulence are inevitable consequences of rapid rotation and low viscosity in the Earth’s core. We use numerical simulations and experiments to investigate the influence of waves and turbulence on the large-scale flow of an electrically conducting fluid in a spherical annulus. The large-scale flow is driven by shear between the inner-core and outer-core boundaries...

An incompressible liquid flow in the gap between two coaxial cylinders, such that the inner rotating (wavy) cylinder has a periodically varying radius along the axial direction while the outer stationary cylinder has a constant radius, is studied experimentally and theoretically. The basic attention is focused on the symmetry-breaking phenomenon of the vortex flow arising from the rotation of t...

Flow quantification inside a conventional metallic stem with only MRI sequences and without contrast media is a difficult task. Usually, depending on the field strength of the imaging system, the inside of such a stent is not easy to visualize and it is not possible to use conventional sequences for velocity (flow) quantification, such as phase contrast imaging. To come over these drawbacks we ...

We study the fundamental problem of spherical Couette flow (SCF) in the presence of heat and under the action of a gravitational field. The flow is considered as unsteady, axisymmetric and the fluid as viscous, incompressible and Newtonian. The numerical technique, which we use, is convergent and consistent and can be applied to 3D or 2D flow motions. We focus our attention to such aspect ratio...

The magnetic field of the Earth is generated by convection in the liquid-core and the energy necessary for this process comes from the cooling of the core which provide several buoyancy sources. The thermodynamics of this system is used to relate the Ohmic dissipation in the core to all energy sources and to model the thermal evolution of the core. If the same dissipation is maintained just bef...

We present numerical simulations of the magnetic field generated by the flow of liquid sodium driven by two counter-rotating impellers (VKS experiment). Using a kinematic code in cylindrical geometry, it is shown that different magnetic modes can be generated depending on the flow configuration. While the time averaged axisymmetric mean flow generates an equatorial dipole, our simulations show ...

This paper presents numerical solutions and idealized analytical solutions of axisymmetric, f -plane models of the tropical cyclone boundary layer. In the numerical model, the boundary layer radial and tangential flow is forced by a specified pressure field, which can also be interpreted as a specified gradient balanced tangential wind field vgr(r) or vorticity field ζgr(r). When the specified ...

This paper presents a voltage stability constrained optimal power flow that is expressed via a bilevel programming framework. The inner objective function is dedicated for maximizing voltage stability margin while the outer objective function is focused on minimization of total production cost of thermal units. The original two stage problem is converted to a single level optimization problem v...

A mathematical analysis has been carried out for the axial flow of a Bingham plastic fluid, in the Concentric Cylinder Viscometer which consists of a cylindrical sample holder (the cup) and a cylindrical spindle (the bob) coaxial with the cup. The fluid to be tested flows through the annular gap of the cup and the bob system, sheared by the rotation of the inner cylinder, while the outer cy...

In this report, the radiation of sound from an annular duct exit with buried inner nozzle system, with jet and bypass flow, is studied. This problem represents a simplified model of the radiation of fan and turbine noise from engine exhausts. The model consist of two semi-infinite ducts. The smaller duct (inner nozzle), whose exit plane coincides with the larger one or extends beyond it, is sit...