Numerical simulations of thermal convection in rapidly rotating spherical fluid shells

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7271959

Sun, Z P

Numerical simulations of thermal convection in rapidly rotating spherical shells of Boussinesq fluid have been carried out with a nonlinear, three-dimensional, time-dependent spectral-transform code. The basic state is hydrostatic, spherically symmetric, and independent of time. The numerical methods, the numerical stability, and the adequacy of the spatial resolution were examined by a benchmarking study. A sequence of bifurcations from the onset of a steadily propagating convective state, to a periodic state, to a quasi-periodic state and thence a chaotic state has been found. Convective solutions at each stage along the route to chaos have been studied. The emphases are on the three-dimensional and time-dependent convective structures and associated mean zonal flow. The spherical shell is heated from both below and within. The boundaries are isothermal and stress-free. The author has also explored the consequences of imposing a spatially varying temperature anomaly on the upper surface of a spherical shell on thermal convection in the shell. The spherical shell is heated from below and cooled from above. The lower boundary is isothermal and both boundaries are rigid and impermeable. The results show that the patterns and amplitudes of the convective motions and associated mean zonal and meridional flows depend largely on the pattern and amplitude of the imposted thermal anomaly. The purpose of this study is to illustrate the influence of thermal conditions in the lower mantle on motions in the Earth's liquid outer core. The author has carried out numerical simulations at both high Taylor and Rayleigh numbers. The spherical shell is heated from below and cooled from above. The boundaries are isothermal and stress-free. Columnar rolls that are quasi-layered in cylindrical radius and associated banded mean zonal flow are obtained. The quasi-layered convective structure and the banded zonal wind are consequent upon both the high Taylor and Rayleigh numbers.

• Research Organization: California Univ., Los Angeles, CA (United States)
• OSTI ID: 7271959
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420400 -- Engineering-- Heat Transfer & Fluid Flow
54 ENVIRONMENTAL SCIENCES
540110
58 GEOSCIENCES
580000* -- Geosciences
ATMOSPHERIC CIRCULATION
CONVECTION
EARTH ATMOSPHERE
EARTH CORE
EARTH MANTLE
ENERGY TRANSFER
FLUID MECHANICS
HEAT TRANSFER
HYDRODYNAMICS
MASS TRANSFER
MATHEMATICAL MODELS
MECHANICS
MOTION
NONLINEAR PROBLEMS
ROTATION
SHELLS
SIMULATION
STATISTICAL MODELS
THREE-DIMENSIONAL CALCULATIONS