Ocean plays an important role in global environment in terms of heat transport and carbon cycle. Carbon is distributed in the ratio of 1:50 between atmosphere and ocean, respectively, and therefore even small fluctuation of carbon budget in the ocean will strongly affect the carbon budget in the atmosphere. Biogeochemical cycle in ocean is driven by marine ecosystem, in particular by marine phytoplankton, and complex multi-phase flow exists in the ocean. Controlled experimental ecosystem is useful in order to understand biochemical flux in multi-phase flow of marine ecosystem. Experimental results using marine phytoplankton. Emiliania huxleyi showed the importance of phytoplankton on carbon flux in the ocean.
We applied the constant-electric-current method to the measurement of concentration of CO2 in a liquid film flow. This method was useful for the instantaneous measurement of void fraction and film thickness in a liquid film flow. The concentration of CO2 in the liquid can be related to the conductivity of the liquid, i. e., the output voltage from the constant-electric-current method by using the dissociation theory. Although the output of the electrodes of this method strictly indicates the conductance-averaged concentration, that value is nearly equal to the cross-section-averaged concentration. Therefore, we can measure the crosssection-averaged concentration using the constant-electric-current method. Besides, this method does not disturb an original flow in a liquid film because we need not to sample the flowing liquid. Furthermore, in the case that the initial conductivity of the liquid can not be neglected, the dissociation theory can be applied provided that the initial conductivity is caused by the dissolution of CO2.
A sequential production device of solid spherical shells is developed using liquid-liquid-gas systems. This system comprises of a cylindrical vessel containing two immiscible liquids and a gas injection orifice at the center of bottom. By controlling the gas flow rate through the orifice and the temperature field of the two-layer liquids, encapsulated liquid drops, i. e., liquid shells with mm-order diameter, are stably and sequentially produced at the interface between the two-layer immiscible liquids in the cylindrical vessel. The encapsulated liquid drops are solidified as they move upward in the upper liquid. In the present paper, the natural convection heat transfer of the two-layer liquids in the cylindrical vessel is examined theoretically. By solving the incompressible Navier-Stokes equations and the energy equations for the two-layer liquids, the suitable design conditions for the sequential production of solid spherical shells are presented. The production device of solid spherical shells in the HTS-turbine oil-air system is improved based on the analysis. Consequently, the production frequency of spherical shells is considerably improved.
A capsule for inspecting conduit interiors has been blown with high stability using spiral air flow. Maintaining stability increases both the accuracy and workability of inspection process in the telecommunication industry. To elucidate this stabilization, the model of the capsule motion in both turbulent and spiral flows has been investigated from a fluid dynamics viewpoint. In a turbulent pipe flow, the air flow is disturbed by the irregularly-rotating wake in the rear of the capsule. This leads to an increase in capsule and air flow instability which in turn makes completion of the inspection process impossible. However, the steep velocity distribution of the ordered spiral airflow positions the wake to the side of the pipe axis. Thus the downstream flow increases its radial pressure gradient resulting in effective capsule stabilization. This capsule stabilization was achieved by synergism between the spiral air flow and capsule.