Magnetic method for stimulating transport in fluids
A method for producing mass and heat transport in fluids, wherein the method does not rely on conventional convection, that is, it does not require gravity, a thermal gradient, or a magnetic field gradient. This method gives rise to a unique class of vigorous, field-controllable flow patterns termed advection lattices. The advection lattices can be used to transport heat and/or mass in any desired direction using only magnetic fields.
1. A method for transporting mass or heat, the method comprising:
providing a suspension of a plurality of anisometric magnetic particles in a fluid;
applying a time-varying biaxial magnetic field to the suspension, wherein the time-varying biaxial magnetic field comprises two components, each having an axis, wherein at least one of the components is a time-dependent field having a frequency and wherein the axes of the two components are not co-linear, and
forming in response to the time-varying biaxial magnetic field an advection lattice comprising the anisometric magnetic particles for the transport of mass or heat by the fluid.
2. The method of claim 1 , wherein the axes of the two components of the time-varying biaxial magnetic field are substantially orthogonal.
3. The method of claim 1 , wherein one component is a dc component.
4. The method of claim 1 , wherein the frequency of at least one of the components is between approximately 10 Hz and approximately 1000 Hz.
5. The method of claim 1 , wherein an amplitude of the time-varying biaxial magnetic field exceeds approximately 50 Gauss rms for each component.
6. The method of claim 1 , wherein the two components are time-dependent fields, each having a frequency, and wherein the waveforms of the two components are sinusoidal with frequencies related as a ratio of integers.
7. The method of claim 6 , wherein the frequencies are related by just intervals.
8. The method of claim 1 , wherein the two components are time-dependent fields, each having a frequency, and wherein the method further comprises forming a time-varying advection lattice by using a non-just frequency interval relationship of the frequencies of the two components.
9. The method of claim 1 , wherein the two components are time-dependent fields, each having a frequency, and wherein waveforms of the two components are selected from the group consisting of sinusoidal waveforms, square waveforms, and sawtooth waveforms.
10. The method of claim 1 , wherein the two components are time-dependent fields, each having a frequency, and wherein the method further comprises applying a third magnetic field approximately normal to a plane of the time-varying biaxial magnetic field.
11. The method of claim 10 , wherein the third magnetic field is a dc field.
12. The method of claim 11 , further comprising inducing mixing in the fluid through chaotic advection.
13. The method of claim 10 , wherein the third magnetic field is a time-dependent field.
14. The method of claim 1 , wherein the two components are time-dependent fields, each having a frequency, and wherein the frequencies of the two components retain a fixed phase relationship.
15. The method of claim 1 , wherein the two components are time-dependent fields, each having a frequency, and wherein the frequencies of the two components are phase-modulated.
16. The method of claim 1 , wherein the advection lattice comprises an array of anti-parallel flow columns that are approximately normal to a plane of the time-varying biaxial magnetic field.
17. The method of claim 1 , wherein the advection lattice comprises an array of columns with helical flow.
18. The method of claim 1 , wherein the anisometric magnetic particles comprise a platelet-like structure.
19. The method of claim 1 , wherein the anisometric magnetic particles are selected from the group consisting of nonmetallic magnetic particles and metallic magnetic particles.
20. The method of claim 1 , wherein the anisometric magnetic particles are coated particles selected from the group consisting of particles with a magnetic interior and a nonmagnetic exterior coating, particles with a nonmagnetic interior and a magnetic exterior coating, and particles with a magnetic interior and a magnetic exterior coating.