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SUMMARYThis paper presents a finite element analysis based on the Lagrangian description for unsteady incompressible viscous fluid flow with a free surface. The behaviour of the fluid is expressed by the unsteady Navier-Stokes equation. For numerical integration in time the fractional step method is used. This method is useful because one can use the same linear interpolation functions for both velocity and pressure. In this paper, four variations of the fractional step method are presented and the numerical results are compared. To confirm the effectiveness of these methods, solitary wave propagation is analysed.

In this paper the vortex shedding around a heatedkooled circular cylinder is numerically simulated by solving the time-dependent Navier-Stokes and energy equations. A finite element method that is referred to as the three-step Taylor-Galerkin method is used to compute these equations. The attention of this study is directed to the investigation of the effect of buoyancy on the vortex street behind the cylinder at constant Reynolds number. The present paper shows the suppression or generation of the von K5umh vortex street behind the cylinder when the cylinder surface is heated or cooled respectively. The relationship between the temperature-induced buoyancy force and the vortex shedding is also discussed through several numerical examples.KEY WORDS: Taylor-Galerkin method; vortex shedding; buoyancy force; von K a m h vortex street

A challenge exists in horticultural greenhouse farming as a result of the current decline in the agriculture labor force in Japan. Although there is a need for cutting-edge technological Information and Communications Technology (ICT) application in agriculture, few smallscale farmers are willing to risk significant capital on sensing technologies. In this study, a simplified smart agriculture system using limited resource expense was developed and applied in a tomato greenhouse. The system's real-time information capability is composed of commercial inexpensive wireless sensor network (WSN) devices, and a developed web database (web DB) for daily activity data collection was used for crop environment monitoring and management. The crop microclimate environment was monitored on the basis of an agroclimatic index, namely, growing degree day (GDD). Microclimate spatiotemporal distributions using GDD were also determined, which showed well-defined microclimate variations within the greenhouse. Crop calendars were embedded into the developed web DB for tomato farms. We drew conclusions for better crop management and crop yields using our smart agriculture system. The applicability of the system based on initial cost, running costs, and the reliability of WSN data makes it cost-effective. Consequently, it could be used for the accurate crop production planning and decision making of cultivation activities.