AN ANALYSIS ON LARGE-SCALE AIR-SEA INTERACTIVE LINKAGES BETWEEN THE TROPICAL INDIAN OCEAN AND THE PACIFIC OCEAN DURING ENSO EVENTS

By utilizing a 3-D atmospheric circulation resolving method, the authors studied the air-sea interactive linkages between the tropical Indian Ocean and the Pacific Ocean in 1979-2008 E1 Nifio-Southern Oscillation （ENSO） events. Their findings showed that evident 3-D gear-coupling characteristics existed in the 1979-2008 ENSO events. Their resolving analyses also suggested that the general circulation showed stronger and wider sinking motions over the eastern Indian Ocean-western Pacific during the mature phase of 1979-2008 ENSO events, compared with the vertical velocities from the U.S. National Centers for Enviornmental Prediction （NCEP） reanalysis data. With their 3-D analysis method, the vertical velocity was resolved by two components, i.e. zonal and meridional components. It was found that the zonal component of the vertical velocities showed a strong sinking motion while the meridional components showed an upward motion during the prevailing phases of the ENSO events. In the tropics, the zonal component of the vertical velocities was found greater than the meridional component, reflecting the dominant characteristics of the vertical velocity, and the overall outcomes showed a strong sinking motion, although the two components also partially offset each other in the processes. Compared with the vertical velocities from NCEP reanalysis, the vertical motions calculated with the 3-D resolving analysis method demonstrate some advantages.

A generalized variational principle and theoretical model for magnetoelastic interaction of ferromagnetic bodies

The quantitative analysis shows that no theoretical model for 3-d magnetoelastic bodies, in literatures to date, can commonly simulate two kinds of distinct experimental phenomena on magnetoelastic interaction of ferromagnetic structures. This makes it difficult to effectively discribe the magnetoelastic mechanical behavior of structures with complex geometry, such as shells. Therefore, it is a key step for simulating magnetoelastic mechanical characteristics of structures with complex geometry to establish a 3-d model which also can commonly characterize the two distinct experimental phenomena. A theoretical model for three dimension magnetizable elastic bodies, which is commonly suitable for the two kinds of experimental phenomena on magnetoelastic interaction of ferromagnetic plates, is presented by the variational principle for the total energy functional of the coupling system of the 3-d ferromagnetic bodies. It is found that for the case of linear isotropic magnetic materials, the magnetic forces obtained by this model include not only the body magnetic force which is the same as that got from the magnetic dipole model, but also a distribution of the magnetic traction on the surface of the magnetizable body. And the value of the traction is equal to the jumping one of the Faraday electromagnetic stress on the two sides of the surface, which does not appear in any model, such as magnetic dipole model and axiomatic model.

FSI simulation of dynamics of fish passing through a tubular turbine based on the immersed boundary-lattice Boltzmann coupling scheme

The anadromous fish can pass through turbines of run-of-the-river hydropower stations to reach the downstream watershed, but their mortality is significant because of the complex turbine structure, the fast-rotating runner, and the special flow patterns. Numerical simulations of the dynamics of fish passing are a challenging task, because the fish motion in the turbines involves a strong fluid-structure interaction (FSI). In this paper, the 3-D immersed boundary-lattice Boltzmann (IB-LB) coupling scheme is proposed to treat the FSI between the water and the fish. The process of one fish and three fish passing through a tubular turbine is simulated on a graphics processing unit (GPU) platform. The fish motion postures (translation and rotation), the fish body pressure distributions and histories are analyzed, and the results are consistent with the previous studies. This paper presents the IB-LB models, the simulation procedures, the specific treatments, and related results, to demonstrate the effectiveness of the IB-LB coupling scheme in simulating FSI problems and its application prospects in developing fish-friendly turbines.