Thermal convection and nonlinear effects of a superfluid /sup 3/He-/sup 4/He mixture in a porous medium

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:5227236

Chien, L C.L.

The convective instability of one-component classical fluids in a porous medium confined between two unbounded slabs was studied. This system behaves like a high Prandtl number bulk fluid. It has boundary conditions similar to the stress-free boundary conditions of bulk one-component classical fluids. Both the amplitude expansion method and the Galerkin method were used to investigate the nonlinear steady convection. Two dimensional rolls are the only stable motion at the onset of convection. Beyond threshold, the steady convection rolls become unstable to formation of cross-roll and zigzag instabilities. Applying the phase-dynamics approach for the zigzag instability, the author obtained the diffusion coefficient D, which can signal the onset of instability. Also investigated was the convective instability of superfluid /sup 3/He-/sup 4/He mixtures in porous media. Assuming no interaction between the average superflow and the porous medium and treating the normal flow in the equation of motion like a classical fluid in a porous medium, it was found that the superfluid mixtures in a porous medium. To investigate the effects of a lateral boundary, the convective instability of classical one-component fluids in porous media inside a box was studied. The zigzag instability does not exist because of the boundary conditions at the side of the box.

• Research Organization: Stanford Univ., CA (USA)
• OSTI ID: 5227236
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CLASSICAL MECHANICS
CONVECTION
DISPERSIONS
ENERGY TRANSFER
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FLUID FLOW
HEAT TRANSFER
HELIUM 3
HELIUM 4
HELIUM ISOTOPES
INSTABILITY
ISOTOPES
LIGHT NUCLEI
MASS TRANSFER
MATERIALS
MECHANICS
MIXTURES
NONLINEAR PROBLEMS
NUCLEI
POROUS MATERIALS
STABLE ISOTOPES
SUPERFLUIDITY