The aim of the CaRu experiment is to investigate the influence of milligravity on the so called Runge-Instability that leads to development of Runge Pictures. Runge-Instability is deeply connected to the field of capillarity as it describes the unsteady spreading of the color appearances that come to existence when a fluid A spreads through a porous structure and this fluid A chemically reacts with a fluid B which the porous structure has been impregnated with before. Capillarity under low gravity is of interest because it can be used to transport fluid fuel in spacecrafts. Therefore there have been studies on this topic for years - recently ZARM from Germany started an experiment on the space station. Despite of the interest in capillarity as such there has not yet been an experiment centered on the Runge-Instability and the influence of milligravity or a throughout exploration of the effect. Scientific research in that direction is relevant, too, because there is an interesting connection between science and art. CaRu would result in production of art in space next to the scientific achievements.
© Dr. Lothar Kuhnert, Berlin
CaRu is going to find out how gravity influences the climb of the Runge-Instability in the direction of the gravitational force. A connection between flow velocity and existence/development of the instability is being expected, as
diffusion is acting against it and grows more important as the fluid moves slower. This leads Dr. Kuhnert to anticipate a critical flow velocity or rather a dimensionless characteristic number. CaRu is going to trace the flow velocity
and the fractal dimension at the spreading rim of the picture to characterize the Runge-instability, which has not been done before.
The main aim of the experiment is to investigate the development of Runge pictures under milligravity. As basic research our project is helping scientist understand the Runge instability better and to get more specific material on this topic. Here for a camera is recording the formation of the Runge pictures under milligravity which will be compared afterwards to a video of the same experiment run on Earth. The data collected from the experiment will be the following:
As an additional objective we want to qualify our experiment for use in space. With this goal we want to increase our knowledge about sounding rockets experiments which will be of use for the students rockets program running at our university. For more details about the experiment.