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Research > Stratified Flows

Stratified flows abound in our surrounding environment; from temperature gradient driven phenomena in the atmosphere to salinity gradient influenced flow in the ocean. We therefore investigate both fundamental and applied aspects of stratified flows to better understand the world around us. Examples that we heave recently studied include: diffusion-driven flow due to sloping boundaries, which we have shown can propel objects; the settling of particles in a stratified ambient; the so-called stratified Boycott effect; and the onset of instability due to a moving sidewall in a stratified fluid.

Funding for our research on stratified flows comes from the NSF.

Spotlight

Sailing on Diffusion

When a density-stratified fluid encounters a sloping boundary, diffusion alters the fluid density adjacent to the boundary, producing spontaneous flow. We have found that diffusion-driven flow can be harnessed as a remarkable means of propulsion, acting as a diffusion-engine that extracts energy from microscale diffusive processes to propel macroscale objects. This mechanism has implications for a environmental systems. [read the paper]

Relevant Publications

  1. Blanchette, F., Peacock, T. and Bush J.W.M., "The Boycott effect in magma chambers," Geophysical Research Letters, 31, L05611 (2004). [link]
  2. Peacock, T., Stocker, R. and Aristoff, J., "An experimental investigation of the angular dependence of diffusion-driven flow," Physics of Fluids, 16, 3503-3505, (2004). [link]
  3. Peacock, T., Blanchette, F. and Bush J.W.M., "The stratified Boycott effect," Journal of Fluid Mechanics, 529, 33-49 (2005). [link]
  4. Heitz, R., Peacock, T. and Stocker, R., "Optimizing diffusion-driven flow in a fissure," Physics of Fluids, 17, Art. No. 128104 (2005). [link]
  5. Yick, K.Y., Stocker, R. and Peacock, T., "Microscale Synthetic Schlieren," Experiments in Fluids, 42 (1), 41-48 (2007). [link]
  6. Blanchette, F., Peacock, T. and Cousin, R., "Stability of a stratified fluid with a vertically moving sidewall," Journal of Fluid Mechanics, 609, 305-317 (2008). [link]
  7. Yick, K.Y., Torres, C.R., Peacock, T. and Stocker, R., "Enhanced drag of a sphere settling in a stratified fluid at small Reynolds number," Journal of Fluid Mechanics, 632, 49-68 (2009). [link]
  8. Allshouse, M.R., Barad, M.F. and Peacock, T., "Sailing on diffusion," submitted to Nature. [link]
  9. Allshouse, M.R. and Peacock, T., "A new way to measure molecular diffusivity," in preparation.

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