17:15 〜 18:30
[SVC31-P09] 気泡と結晶の相互作用を支配するパラメーター
キーワード：アナログ実験、気泡と結晶の相互作用
In the magma, the interaction between suspended crystals and the rising bubble due to buoyancy is important because their stratification through the rheological properties and bulk densities. Belien et al. (2010) showed that there are three interactionstyleswithchangingbubblediameter bylaboratoryexperimentsusingan analog material: a single plastic cube and a controlled single bubble in viscous liquid. However, the crystal - bubble interaction is still poorly understood because factors determining the interaction styles have not been revealed in terms of dimensionless parameters. In order to solve this problem, we try to find the dimensionless parameters by the analogue experiments with varying viscosity and size ratio of solid cube to bubble.
The experiments are performed in the tank filled with viscous liquid (analog material of silicate melt) and prepared six different viscosity(0.041 Pa・s – 47.2 Pa・s). The plastic cube (analog material of crystal) with 10 mm is suspended in liquid by a rod. The bubble is injected into the liquid from 11cm below the plastic cube from a syringe connected to a motor controlled by the PC program by which we can change the initial bubble size. We examine the probability of occurrence of three styles of interaction: "stuck", "pass", and "split"; "stuck" in which a bubble stays below the solid cube, "pass" in which a bubble passes around the cube and "split" in which a bubble splits into two bubbles. To determine the probabilities, we did the repetition of 10 times for the same condition of initial bubble radii and viscosity.
In our experiments, we observed two styles of the interaction of "stuck" and "pass" and not "split". It is found that the smaller bubble tends to “stuck”, on the other hand, the probability of “pass” became higher as the bubble radii are larger. To reveal the boundary of “stuck” and “pass”, we estimated three parameters in my previous research (Ikeda and Toramaru, 2020 JpGU meeting) ; the size ratio of the crystal and the bubble, the Bond number(Bo), which represents the deformation scale of the bubble caused by buoyancy, and the Reynolds number(Re), which is the ratio of inertial to viscous forces. In high Re regime, the bubble bounces back after impacting the crystal because of inertia force. In this region, the bubble is easily deformed because the Bo is large. Because of the both effect of inertial force and the bubble deformation, “pass” occurs even if the size ratio of crystal and bubble is smaller than in other regions. On the other hand, in low Re regime, rebounding does not occur because the viscous force is larger than inertia force. In this region, Bo is also small, therefore, bubble deformation is difficlut to occur. This indicates that "pass" does not occur unless the size ratio of bubble and crystal is larger than in other regions.
In this presentation, we measured the rheology of analog liquid used in this experiments. Using the measured viscosity for Re, it was found that the boundary value of the size ratio of crystal and bubble is constant as the Re increased. This indicates that the viscosity does not affect the interaction-style boundary. To be more precise in measuring the size of bubble, we used the bubble radius calculated from the area measured from the images. From these results, we propose the new criterion dividing “stuck” and “pass” as the critical value of product of Bo and the size ratio: in one regime, “stuck “ occurs when both of Bo and the size ratio of crystal and bubble were small. in the other regime, “pass” occurs when the Bo and the size ratio of crystal and bubble were large.
The experiments are performed in the tank filled with viscous liquid (analog material of silicate melt) and prepared six different viscosity(0.041 Pa・s – 47.2 Pa・s). The plastic cube (analog material of crystal) with 10 mm is suspended in liquid by a rod. The bubble is injected into the liquid from 11cm below the plastic cube from a syringe connected to a motor controlled by the PC program by which we can change the initial bubble size. We examine the probability of occurrence of three styles of interaction: "stuck", "pass", and "split"; "stuck" in which a bubble stays below the solid cube, "pass" in which a bubble passes around the cube and "split" in which a bubble splits into two bubbles. To determine the probabilities, we did the repetition of 10 times for the same condition of initial bubble radii and viscosity.
In our experiments, we observed two styles of the interaction of "stuck" and "pass" and not "split". It is found that the smaller bubble tends to “stuck”, on the other hand, the probability of “pass” became higher as the bubble radii are larger. To reveal the boundary of “stuck” and “pass”, we estimated three parameters in my previous research (Ikeda and Toramaru, 2020 JpGU meeting) ; the size ratio of the crystal and the bubble, the Bond number(Bo), which represents the deformation scale of the bubble caused by buoyancy, and the Reynolds number(Re), which is the ratio of inertial to viscous forces. In high Re regime, the bubble bounces back after impacting the crystal because of inertia force. In this region, the bubble is easily deformed because the Bo is large. Because of the both effect of inertial force and the bubble deformation, “pass” occurs even if the size ratio of crystal and bubble is smaller than in other regions. On the other hand, in low Re regime, rebounding does not occur because the viscous force is larger than inertia force. In this region, Bo is also small, therefore, bubble deformation is difficlut to occur. This indicates that "pass" does not occur unless the size ratio of bubble and crystal is larger than in other regions.
In this presentation, we measured the rheology of analog liquid used in this experiments. Using the measured viscosity for Re, it was found that the boundary value of the size ratio of crystal and bubble is constant as the Re increased. This indicates that the viscosity does not affect the interaction-style boundary. To be more precise in measuring the size of bubble, we used the bubble radius calculated from the area measured from the images. From these results, we propose the new criterion dividing “stuck” and “pass” as the critical value of product of Bo and the size ratio: in one regime, “stuck “ occurs when both of Bo and the size ratio of crystal and bubble were small. in the other regime, “pass” occurs when the Bo and the size ratio of crystal and bubble were large.