17:15 〜 19:15
[O08-P07] Star-shaped pattern formed in experiments with the colloidal aggregated film
★Invited Papers
キーワード：パターン形成、コロイド凝集、ソフトマター
There are many phenomena associated with colloidal aggregation, such as mud precipitation and mud cracking in our life.
We focus on two types of experimental results on pattern formation caused by colloidal aggregation.
One is the star-shaped pattern formed by magnetic fluid on the surface of milk. When a droplet of the magnetic fluid is placed on the milk, the magnetic fluid with low surface tension spreads on the milk surface and the star-shaped pattern is formed spontaneously. As the magnetic fluid is an acid solution, the colloids contained in the milk aggregate when the magnetic fluid is mixed with the milk. Thus, the thin colloidal film is formed on the milk surface during the spreading process of the magnetic fluid. We considered that the pattern is formed by the colloidal aggregates and the sweeping of the colloidal aggregates caused by the flow under the film. Our consideration is supported by our phenomenological model to show the pattern formation. We show the detailed experimental results and discuss the dynamics.
The second is on the pattern formation observed in the fracture phenomena of the thin film by colloidal aggregates. When we make a small hole in the film on the liquid surface, the crack develops. The crack pattern is similar to the star shaped pattern. The film has an elastic property. In addition, when cracks develop, the viscous dissipation occurs as viscous fluid flows under the film. We consider that the fracture phenomena depending on Young's modulus of the film and the viscous dissipation occurring during the crack development are important factors for the pattern formation. We will show the phenomenological model and discuss the dynamics.
We focus on two types of experimental results on pattern formation caused by colloidal aggregation.
One is the star-shaped pattern formed by magnetic fluid on the surface of milk. When a droplet of the magnetic fluid is placed on the milk, the magnetic fluid with low surface tension spreads on the milk surface and the star-shaped pattern is formed spontaneously. As the magnetic fluid is an acid solution, the colloids contained in the milk aggregate when the magnetic fluid is mixed with the milk. Thus, the thin colloidal film is formed on the milk surface during the spreading process of the magnetic fluid. We considered that the pattern is formed by the colloidal aggregates and the sweeping of the colloidal aggregates caused by the flow under the film. Our consideration is supported by our phenomenological model to show the pattern formation. We show the detailed experimental results and discuss the dynamics.
The second is on the pattern formation observed in the fracture phenomena of the thin film by colloidal aggregates. When we make a small hole in the film on the liquid surface, the crack develops. The crack pattern is similar to the star shaped pattern. The film has an elastic property. In addition, when cracks develop, the viscous dissipation occurs as viscous fluid flows under the film. We consider that the fracture phenomena depending on Young's modulus of the film and the viscous dissipation occurring during the crack development are important factors for the pattern formation. We will show the phenomenological model and discuss the dynamics.