|
| Title: | Dynamics
of suspended particles in periodic vortex flows | | Principal
Investigator: | Hendrik C. KUHLMANN (ZARM - University of Bremen) | | Co-Investigator: | Hiroshi
KAWAMURA
Dietrich SCHWABE
Eckart MEIBURG |  | Science
University of Tokyo
University of Giessen
University of California at Santa
Barbara |
 | Salient
points | In fluid science field, recent interests move to high-speed
turbulence flow, which produces a lot of small vortex, instead of gentle flow.
It is a reason why the studies of a turbulence flow are require for the industries
such as a design of aerospace crafts. On the other hand, the surface driven flow
like a thermocapillary flow is not fully understood in spite of its importance
from scientific and industrial point of view.
Microgravity experiments
of thermocapillary flow carried out frequently. Microgravity conditions would
reveal the essence of the thermocapillary flow because buoyancy convection is
suppressed and the larger liquid bridge can be formed. The thermocapillary flow
has been investigating to contribute the improvement of materials processing.
Convection driven by both buoyancy and thermocapillary are induced during materials
processing. The convection cannot be controlled actively since the understanding
of thermocapillary flow is not enough. Therefore, fluid physics should be progressed
by piling up the result of thermocapillary flow.
In Japan, thermocapillary
flow is systematically investigated from two points of view which are to advance
a fluid physics by using a transparent model fluid and to improve the techniques
of materials processing by using a practical material. The visualization techniques
have been developed though a Japanese sounding rocket experiment and these become
most advanced experimental methods. Both internal and surface flow can be stereoscopically
visualized in the case of transparent model fluid. Therefore, its detail information
of the complicated three-dimensional flow provides us to understand the oscillatory
flow. Convection of opaque fluid such as molten metal is invisible usually. However,
even a convection of molten semiconductor can visualize since the observation
equipment with X-ray radiography has been developed. Hereby, the experiment utilized
sounding rocket played important roles to develop the observation system and to
start the systematically understanding of the oscillatory thermocapillary flow.
The
complex flow such as oscillatory motion will be understand progressively because
the sophisticated experimental techniques were developed. There are two problems
to solve concerning the thermocapillary flow. These are (1) To make clear the
condition to occur oscillatory flows and (2) To understand the reason why the
thermocapillary flow change from steady to oscillatory. The microgravity experiment
will perform to answer the first problem in the first KIBO utilization theme.
The onset of complex oscillatory flows in both model fluid and molten semiconductor
will be observed. The theme of this selection is positioned to solve the second
problem.
The themes utilizing the International Space Station in early
stage allow understanding the transition behaviors of complicated thermocapillary
flow. The results will not only promote better understanding of thermocapillary
flow but also contribute the progression of fluid physics in surface problems.
| Brief
summary |
It has recently been shown that, when thermocapillary
convection occurs in liquid suspended particles, the initially randomly distributed
particles accumulate and form a non-trivial pattern. This phenomenon depends leaving
on the flow pattern. This experiment seeks to develop a thorough physical understanding
of the conditions under which the accumulation structures form.
A Japanese
Co-investigator will collaborate to carry out the initial microgravity experiment.
The results will contribute general information concerning the inclusion of particles
during material processing
Last Updated : Jan.
28, 2002
|
