Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 6 of 6
Full-Text Articles in Physical Sciences and Mathematics
Magnetic Control Of Convection In Nonconducting Diamagnetic Fluids, J. Huang, D. D. Gray, Boyd F. Edwards
Magnetic Control Of Convection In Nonconducting Diamagnetic Fluids, J. Huang, D. D. Gray, Boyd F. Edwards
All Physics Faculty Publications
Inhomogeneous magnetic fields exert a body force on electrically nonconducting, diamagnetic fluids. This force can be used to compensate for gravity and to control convection. The field effect on convection is represented by a dimensionless vector parameter Rm=(μ0αχ0d3ΔT/ρ0νDT)(H⋅∇H)r=0ext, which measures the relative strength of the induced magnetic buoyancy force due to the applied field gradient. The vertical component of this parameter competes with the gravitational buoyancy effect and a critical relationship between this component and the Rayleigh number is identified for the onset of convection. …
Magnetic Control Of Convection In Nonconducting Paramagnetic Fluids, J. Huang, Boyd F. Edwards, D. D. Gray
Magnetic Control Of Convection In Nonconducting Paramagnetic Fluids, J. Huang, Boyd F. Edwards, D. D. Gray
All Physics Faculty Publications
An inhomogeneous magnetic field exerts a magnetic body force on magnetically permeable fluids. A recent experiment [D. Braithwaite, E. Beaugnon, and R. Tournier, Nature (London) 354, 134 (1991)] demonstrates that this force can be used to compensate for gravity and to control convection in a paramagnetic solution of gadolinium nitrate. We provide the theory of magnetically controlled convection in a horizontal paramagnetic fluid layer heated from either above or below. Our theoretical predictions agree with the experiments.
Thermoconvective Instability Of Paramagnetic Fluids In A Uniform Magnetic Field, J. Huang, Boyd F. Edwards, D. D. Gray
Thermoconvective Instability Of Paramagnetic Fluids In A Uniform Magnetic Field, J. Huang, Boyd F. Edwards, D. D. Gray
All Physics Faculty Publications
The effect of a uniform oblique magnetic field on a laterally unbounded insulating paramagnetic fluid layer heated from below is studied using a linear stability analysis of the Navier–Stokes equations supplemented by Maxwell’s equations and the appropriate magnetic body force. Two-dimensional rolls in an arbitrary vertical plane are considered. Longitudinal rolls with axes parallel to the horizontal component of the field are the rolls most unstable to convection. The corresponding critical Rayleigh number and critical wavelength for the onset of such rolls are less than the well-known Rayleigh–Bénard values in the absence of magnetic fields. Vertical fields maximize these deviations, …
Onset Of Convection For Autocatalytic Reaction Fronts In A Vertical Slab, J. Huang, D. A. Vasquez, Boyd F. Edwards, P. Kolodner
Onset Of Convection For Autocatalytic Reaction Fronts In A Vertical Slab, J. Huang, D. A. Vasquez, Boyd F. Edwards, P. Kolodner
All Physics Faculty Publications
A fully three-dimensional linear stability analysis shows that ascending autocatalytic reaction fronts in vertical slabs are unstable to convection for large-wavelength perturbations at all finite values of the dimensionless driving parameter S=δga3/νDC. This parameter involves a fractional density difference δ between the unreacted and reacted fluids, the acceleration of gravity g, the slab width a, the kinematic viscosity ν, and the catalyst molecular diffusivity DC. Buoyancy dominates over the competing curvature dependence of the front velocity in a band 0c of unstable dimensionless wave numbers, with qc→S/24 as S→0 and qc …
Onset Of Convection For Autocatalytic Reaction Fronts: Laterally Bounded Systems, D. A. Vasquez, Boyd F. Edwards, J. W. Wilder
Onset Of Convection For Autocatalytic Reaction Fronts: Laterally Bounded Systems, D. A. Vasquez, Boyd F. Edwards, J. W. Wilder
All Physics Faculty Publications
Linear hydrodynamics yields the onset of convection for ascending autocatalytic reaction fronts in laterally bounded geometries. The system is studied in the limit of infinite and zero thermal diffusivity. For convection in a vertical slab of thickness a or a long vertical cylinder of radius a, the appropriate dimensionless driving parameter scrS=δga3/νDc involves the fractional density difference δ between the unreacted and reacted fluids, the acceleration of gravity g, the kinematic viscosity ν, and the catalyst molecular diffusivity Dc. Calculated critical values scrSc for onset of convection agree with recent experiments on iodate–arsenous acid …
Onset Of Convection For Autocatalytic Reaction Fronts: Laterally Unbounded System, Boyd F. Edwards, J. W. Wilder, K. Showalter
Onset Of Convection For Autocatalytic Reaction Fronts: Laterally Unbounded System, Boyd F. Edwards, J. W. Wilder, K. Showalter
All Physics Faculty Publications
The linear stability of exothermic autocatalytic reaction fronts that convert unreacted fluid into a lighter reacted fluid is considered using the viscous thermohydrodynamic equations. For upward front propagation and a thin front, the discontinuous jump in density at the front is reminiscent of the Rayleigh-Taylor problem of an interface between two immiscible fluids, whereas the vertical thermal gradient near the front is reminiscent of the Rayleigh-Bénard problem of a fluid layer heated from below. The problem is also similar to flame propagation, except that here the front propagation speed is limited by catalyst diffusion rather than by activation kinetics. For …