We investigate the evolution of magnetohydrodynamic (or hydromagnetic as coined by Chandrasekhar) perturbations in the presence of stochastic noise in rotating shear flows. The particular emphasis is the flows whose angular velocity decreases but specific angular momentum increases with increasing radial coordinate. Such flows, however, are Rayleigh stable but must be turbulent in order to expl...

Laminar and turbulent pipe flow of a ferrofluid with an imposed linearly polarized, oscillating, magnetic field is examined here. Experimental results show a fractional pressure drop dependence on flow rate, magnetic field strength, and oscillation frequency. Calculations are presented, which show that ferrofluid theory can explain the flow phenomena in laminar and turbulent pipe flow. The mode...

We present a review of the different models that have been proposed to explain reversals of the magnetic field generated by a turbulent flow of an electrically conducting fluid (fluid dynamos). We then describe a simple mechanism that explains several features observed in palaeomagnetic records of the Earth's magnetic field, in numerical simulations and in a recent dynamo experiment. A similar ...

The nature of dynamo action in shear flows prone to magnetohydrodynamc instabilities is investigated using the magnetorotational dynamo in Keplerian shear flow as a prototype problem. Using direct numerical simulations and Newton's method, we compute an exact time-periodic magnetorotational dynamo solution to three-dimensional dissipative incompressible magnetohydrodynamic equations with rotati...

Numerical simulations of 3D collisional drift-wave turbulence in a sheared magnetic field are presented which demonstrate that fluctuations are self-sustaining even though the linear eigenmodes of the system are all damped. An analytic calculation reveals that the source of the turbulence is a nonlinear streaming instability in which radial flows extract energy from the ambient density gradient...

Probability density functions (PDFs) of scale-dependent energy fluctuations, P[deltaE(l)] , are studied in high-resolution direct numerical simulations of Navier-Stokes and incompressible magnetohydrodynamic (MHD) turbulence. MHD flows with and without a strong mean magnetic field are considered. For all three systems it is found that the PDFs of inertial range energy fluctuations exhibit self-...

influence of a vent hood at the exit of exhaust flue gas and flue baffles in the firetube on the temperature and flow fields of a gas tank water heater, as well as thestructure and amount of heat transferred to the water tank has been studiednumerically using two-dimensional steady state finite element simulation.observations show that without a vent hood, there is a downward gas flow in theflu...

The feasibility of a mean-field dynamo in nonhelical turbulence with a superimposed linear shear is studied numerically in elongated shearing boxes. Exponential growth of the magnetic field at scales much larger than the outer scale of the turbulence is found. The characteristic scale of the field is lB proportional S(-1/2) and the growth rate is gamma proportional S, where S is the shearing ra...

Sunspots are concentrations of magnetic field on the visible solar surface that strongly affect the convective energy transport in their interior and surroundings. The filamentary outer regions (penumbrae) of sunspots show systematic radial outward flows along channels of nearly horizontal magnetic field. These flows were discovered 100 years ago and are present in all fully developed sunspots....

Fluid flow around bluff bodies occurs in numerous fields of science and engineering, such as flows pass vehicles, cables, towers and bridges. These flows have been studied experimentally and numerically for the last several decades. The investigation of flow around high-speed trains is an important application of bluff bodies. Fluid flow, aerodynamic forces and moments, separation and wake regi...