Dissipative, forced turbulence in two-dimensional magnetohydrodynamics

Technical Report · Thu Jan 01 04:00:00 EST 1976

DOI:https://doi.org/10.2172/7130489· OSTI ID:7130489

Fyfe, D.; Montgomery, D.; Joyce, G.

The equations of motion for turbulent two-dimensional magnetohydrodynamic flows are solved in the presence of finite viscosity and resistivity, for the case in which external forces (mechanical and/or magnetic) act on the fluid. The goal is to verify the existence of a magnetohydrodynamic dynamo effect which is represented mathematically by a substantial back-transfer of mean square vector potential to the longest allowed Fourier wavelengths. External forces consisting of a random part plus a fraction of the value at the previous time step are employed, after the manner of Lilly for the Navier-Stokes case. The regime explored is that for which the mechanical and magnetic Reynolds numbers are in the region of 100 to 1000. The conclusions are that mechanical forcing terms alone cannot lead to dynamo action, but that dynamo action can result from either magnetic forcing terms or from both mechanical and magnetic forcing terms simultaneously. Most real physical cases seem most accurately modelled by the third situation. The spatial resolution of the 32 x 32 calculation is not adequate to test accurately the predictions of the spectral power laws previously arrived at on the basis of the assumption of simultaneous cascades of energy and vector potential. Some speculations are offered concerning possible relations between turbulent cascades and the ''disruptive instability.''

• Research Organization: National Center for Atmospheric Research, Boulder, CO (USA); Iowa Univ., Iowa City (USA). Dept. of Physics and Astronomy
• Sponsoring Organization: US Energy Research and Development Administration (ERDA)
• OSTI ID: 7130489
• Report Number(s): COO-2059-55
• Country of Publication: United States
• Language: English

Related Subjects

640430* -- Fluid Physics-- Magnetohydrodynamics
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DIFFERENTIAL EQUATIONS
DIRECT ENERGY CONVERTERS
EQUATIONS
EQUATIONS OF MOTION
FLUID FLOW
FLUID MECHANICS
HYDRODYNAMICS
MAGNETOHYDRODYNAMICS
MATHEMATICAL MODELS
MECHANICS
MHD GENERATORS
NAVIER-STOKES EQUATION
TURBULENT FLOW
TWO-DIMENSIONAL CALCULATIONS