A sphere settling in a stratified fluid at small Reynolds number
Name
316797990-MIT.pdf
Description
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Checksum (MD5)
1dbb6472d69e1d1d7b62134413ff87d2
Author(s)
Yick, King-Yeung, 1978-
Advisor(s)
Roman Stocker.
Date Issued
2008
Publisher
Massachusetts Institute of Technology
Abstract
We present a combined theoretical, experimental and numerical investigation of a sphere settling in a linearly stratified fluid at low Reynolds number (0.01
(cont.) By analyzing the numerical velocity, pressure, density and vorticity fields around the sphere, we found that the pressure and viscous drags both increased with stratification. Combining these analyses with the investigations on isopycnal perturbations around the sphere and the buoyancy force in the wake, we conclude that the bulk of the wake does not contribute to the drag. Based on the experimental and numerical results, we derived a scaling argument which suggests that the added drag results from the buoyancy of the fluid in a small region of width (v/N)1/2 around the sphere. Here the physical mechanism responsible for the added drag in a stratified fluid at low Re is drastically different from mechanisms proposed at higher Re. The observed increase in drag could enhance retention time of particles at density interfaces as the parameter regime studied here applies to small particles in the ocean and affects the ecology of marine microorganisms by influencing particle-organism interactions.
Description
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 2008.
Includes bibliographical references (p. 87-91).
Subjects
Mathematics.
MIT Department
Massachusetts Institute of Technology. Department of Mathematics
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