SAJE

Starting point / motivation

JEREMI is a Japanese-European space experiment (Japan European Research Experiment on Marangoni Instability), which is planned to be carried out in the Fluid Physics Experiment Facility (FPEF) of the Japanese module KIBO on the ISS.

The experiment, the launch date of which is planned for late 2019, is supported jointly by ESA and JAXA. Researchers from Belgium, Japan, Austria, Spain and Great Britain participate in the experiment.

Contents and goals

The influence on the flow of the heat transport through the interface between liquid and gas of an axisymmetric thermocapillary liquid bridge will be investigated in the JEREMI experiment. A further subject of investigation are particle accumulation structures.

Methods

The microgravity conditions and the accurately controlled gas flow minimize perturbing buoyancy effects and enable measurements with hitherto unmatched benchmark quality. Of decisive importance for all experiments foreseen in JEREMI is the critical point, at which the steady axisymmetric flow becomes unstable, and beyond which an azimuthally traveling wave forms in the flow.

The critical point corresponds to a critical Reynolds number of the thermocapillary flow, which depends on the geometry and, in particular, on the gas-phase conditions. In this project the critical Reynolds number and the structure of the three-dimensional supercritical flow will be computed by means of a numerical linear stability analysis, since conventional numerical simulations are either too imprecise or require excessively long computational times.

Expected results

The core of the numerical code for the linear stability analysis, MaranStable, has been developed in the framework of an ASAP 6 project. The objective of the current project is the utilization and extension of the code.

• Numerical data will be computed, which are required by the experimentalists in JEREMI. By prior knowledge of the critical point the time-consuming search for the critical point can be omitted, saving valuable time on the ISS.
• The numerical data represent an important basis for comparison with the JEREMI measurements. The data validated this way will yield new insights regarding the manipulation of thermocapillary flows, as the suppression of time-dependent flows is of great importance for technical applications.
• The extensions to be implemented in the code MaranStable will provide a better understanding of the influence of possible sources of error (impurities) and enable an optical correction of measured particle trajectories, which spontaneously de-mix to form curious particle patterns.
• The numerical code will be made operable via a graphical user interface (GUI) and it will be provided to scientists and students for free.

Overall, the project serves the design and operation of the JEREMI experiment, which should deliver new findings about the control of thermocapillary flows and which should clarify the phenomenon of spontaneous de-mixing of particles in these flows.

Coordinator

TU Vienna - Institute of Fluid Mechanics and Heat Transfer

TU Vienna
Institute of Fluid Mechanics and Heat Transfer
Prof. Dr. Hendrik Kuhlmann
Getreidemarkt 9
A-1090 Vienna