Scientific and Technical Aerospace Reports Volume 39 April 6, 2001

to be done is the full coupled system in which the flow is altered by the morphology. This would involve a 3D, time-dependent
calculation of the full free-boundary problem--a daunting task. However, the cases discussed would guide the computationalist
in this effort.
Author (revised)
Convection; Morphology; Stability
20010024941 University of Southern California, Los Angeles, CA USA
The Dynamics of Miscible Interfaces: A Space Flight Experiment
Maxworthy, Tony, University of Southern California, USA; Meiburg, Eckart, California Univ., USA; Proceedings of the Fifth
Microgravity Fluid Physics and Transport Phenomena Conference; December 2000, pp. 1102-1123; In English; See also
20010024890; No Copyright; Avail: CASI; A03, Hardcopy; A10, Microfiche
Experiments as well as accompanying simulations are described that serve in preparation of a space flight experiment to study
the dynamics of miscible interfaces. The investigation specifically addresses the importance of both nonsolenoidal effects as well
as nonconventional Korteweg stresses in flows that give rise to steep but finite concentration gradients. The investigation focuses
on the flow in which a less viscous fluid displaces one of higher viscosity and different density within a narrow capillary tube.
The fluids are miscible in all proportions. An intruding finger forms that occupies a fraction of the total tube diameter. Depending
on the flow conditions, as expressed by the Peclet number, a dimensionless viscosity ratio, and a gravity parameter, this fraction
can vary between approximately 0.9 and 0.2. For large Pe values, a quasi-steady finger forms, which persists for a time of O(Pe)
before it starts to decay, and Poiseuille flow and Taylor dispersion are approached asymptotically. Depending on the specific flow
conditions, we observe a variety of topologically different streamline patterns, among them some that leak fluid from the finger
tip. For small Pe values, the flow decays from the start and asymptotically reaches Taylor dispersion after a time of O(Pe). Comparisons
between experiments and numerical simulations based on the ’conventional’ assumption of solenoidal velocity fields and
without Korteweg stresses yield poor agreement as far as the Pe value is concerned that distinguishes these two regimes. As one
possibility, we attribute this lack of agreement to the disregard of these terms. An attempt is made to use scaling arguments in order
to evaluate the importance of the Korteweg stresses and of the assumption of solenoidality. While these effects should be strongest
in absolute terms when steep concentration fronts exist, i.e., at large Pe, they may be relatively most important at lower values
of Pe. We subsequently compare these conventional simulations to more complete simulations that account for nonvanishing
divergence as well as Korteweg stresses. While the exact value of the relevant stress coefficients are not known, ballpark numbers
do exist, and their use in the simulations indicates that these stresses may indeed be important. We plan to evaluate these issues
in detail by means of comparing a space experiment with corresponding simulations, in order to extract more accurate Korteweg
stress coefficients, and to confirm or deny the importance of such stresses.
Author (revised)
Solubility; Numerical Analysis; Liquid-Liquid Interfaces; Fluid Dynamics
20010024942 Iowa Univ., Iowa City, IA USA
Longitudinal and Transverse Waves in Coulomb Crystals Formed in a Dusty Plasma
Bhattacharjee, A., Iowa Univ., USA; Wang, X., Iowa Univ., USA; Hu, S., Iowa Univ., USA; Proceedings of the Fifth Microgravity
Fluid Physics and Transport Phenomena Conference; December 2000, pp. 1124-1125; In English; See also 20010024890; No
Copyright; Abstract Only; Available from CASI only as part of the entire parent document
A unified theoretical treatment of longitudinal (or compressional) and transverse modes in Coulomb crystals formed in a
dusty plasma is given. Dispersion relations are obtained for two-dimensional and three-dimensional triangular lattices with hexagonal
symmetry. Although the acoustic limit is isotropic in all cases, the functional dependence of the dispersion relations on the
screening parameter K is shown to depend sensitively on the dimensionality of the crystal. Dispersion relations are obtained for
compressional and transverse lattice waves dominated by near-neighbor interactions. Theoretical predictions are compared quantitatively
with two recent experiments, and new dispersion relations that can be tested by future experiments are identified.
Author (revised)
Crystals; Longitudinal Waves; Transverse Waves; Dispersions
20010024943 Notre Dame Univ., Dept. of Physics, IN USA
Diffusive Coarsening of Liquid Foams in Microgravity
Veretennikov, I., Notre Dame Univ., USA; Glazier, J. A., Notre Dame Univ., USA; Proceedings of the Fifth Microgravity Fluid
Physics and Transport Phenomena Conference; December 2000, pp. 1126-1136; In English; See also 20010024890; No Copyright;
Avail: CASI; A03, Hardcopy; A10, Microfiche
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