In this study, based on complex network science, we propose a new method to determine the location of the distributed generators such that the efficiency and the fault tolerance of the power grid can be improved. In the case of using only network-topology data, the numerical experiments show that the arrangement of the distributed generators which increases the fault tolerance produces some location deviation. It is found that this result can be explained by the lowest capacity allocated to a link, and increasing the lowest value of the capacity enables more efficient arrangement of the distributed generators without reducing the fault tolerance. In the case of using the network data which have some properties of a real power grid, we find a new explanation variable to analyze the power loss of the power grid evaluated by an exact formula used in the field of electrical engineering.
In this paper, a finite-volume method on a moving unstructured computational grid for simulation of incompressible flows is presented and developed. In order to strictly assure both physical and geometric conservation laws, the unstructured moving-grid finite-volume method is constructed based on four-dimensional control volume in which space and time are unified. In the method, the velocity and the pressure are connected through a fractional step approach in four-dimensional control volume. We show the detailed formulation of the method and that the method works effectively for numerical simulations of flows including moving boundary. Furthermore, the method is applied for coupled simulation of fluid and motion dynamics. The motion equation with six degrees of freedom is solved in a coupled manner together with the fluid Navier-Stokes equations. Hukidama, which is a japanese toy that has been around since long ago, is lifted up in a jet stream while swinging. The motion of Hukidama is demonstrated and it is shown that the method works effectively for coupled simulation of fluid and motion dynamics.
A wall boundary condition represented by polygons was presented by Harada et al.(31) based on the moving particle semi-implicit (MPS)(1) method to reduce the memory cost and calculation time for the wall particles. However, the inaccuracy of the wall weight function near a non-planar wall boundary causes the unphysical motion of the fluid. Therefore, this paper proposes an improved wall weight function for non-planar wall boundaries. Hydrostatic and dam break simulations with and without a wedge in a water tank are conducted to demonstrate the improvement.
A thrown boomerang flies along an arch path and returns to the thrower. The flying motion is a complex motion caused by the gyroscopic precession which is the coupled phenomenon of air-flow and boomerang-motion. In this study, the flying motion of the boomerang was demonstrated using the numerical simulation and we showed influences of the figure of the boomerang on the flying motion of the boomerang. In the numerical simulation, we combined Moving-Grid Finite-Volume Method for fluid-flow solver, the Forward-Euler Finite-Difference Method for body-motion solver and the Quaternion for representation of body-rotation to solve the coupled phenomenon of air-flow and boomerang-motion. The moving-grid finite-volume method is constructed based on four-dimensional control volume in which space and time are unified and assures strictly both physical conservation laws and geometric conservation laws. The motion equation with six degrees of freedom was solved in a coupled manner together with the Navier-Stokes equations. Furthermore, the experiment was performed to validate the computational results and the computational results showed good agreement with the experimental results. In addition, it was shown that the angle of wing’s flap and the angle of incidence have great effect on the path of the boomerang.