Context. As a universally accepted definition of vortex has not yet been established, the community lacks an unambiguous and rigorous method for identifying vortices in fluid flows. Such would be useful conducting robust statistical studies on highly dynamical turbulent systems such as solar atmosphere. Aims. We aim to develop innovative automated methodology identification based local global c...

Optical vortices are always created or annihilated as vortex dipoles-pairs with opposite topological charge. Here a quantity, consisting of the transverse first and second derivatives of the optical field, is derived with which one can distinguish between vortex dipole annihilation and creation events. Analytical and numerical examples are provided as a demonstration of the method.

A general method based on adjoint formulation is discussed for the optimal control of distributed parameter systems (including boundary parameter) which is especially suitable for large dimensional control problems. Strategies for efficient and robust implementation of the method are described. The method is applied to the problem of controlling vortex shedding behind a cylinder (through suctio...

Submitted for the DFD16 Meeting of The American Physical Society The boundary-constraint method for constructing vortex-surface fields1 SHIYING XIONG, YUE YANG, Peking Univ — We develop a boundaryconstraint method for constructing the vortex-surface field (VSF) in a threedimensional fluid velocity field. The isosurface of VSF is a vortex surface consisting of vortex lines, which can be used to ...

An approximate method is proposed for determining the aerodynamic effect of coherent vortex structures (CVS) atmospheric turbulence on an aircraft. As a source CVS wind wakes arising when flows around mountain massif Son Tra peninsula, located near Da Nang airport, and wake behind Su-27 type aircraft in landing configuration are considered. Modeling formation structure carried out by grid withi...

The flow control on the separation bubble and the large scale vortex is important in the turbo machine. Recently, a new approach using the plasma actuators is proposed to control the separation bubble and the large scale vortex. The aim of this study is to control the large scale vortex behind a flat plate using the plasma actuators. The effect of the three dimensional jet induced by the plasma...

We investigate the focusing properties of a femtosecond vortex light pulse focused by a high numerical aperture objective. By using the Richards-Wolf vectorial diffraction method, the intensity distribution, the velocity variation and the orbital angular momentum near the focus are studied in great detail. We have discovered that the femtosecond vortex light pulse can travel at various speeds, ...

We propose an experimental way to determine the pairing states for the unconventional superconductor CuxBi2Se3. Using the spectral polynomial expansion method, we numerically calculate the local density of states (LDOS) in the multi-orbital tight-binding model and analytically obtain the zero-energy solution around a vortex. Both calculations reveal that a quantized vortex is spin-polarized for...

analysis of the flow passing cylindrical obstacles is one of the basic issues in fluid dynamics and is of great importance. many surveys have been conducted to investigate the velocity field in potential and viscous flows, as a basis for finding pressure field, and investigation of forces exerted by fluid on obstacles such as uplift and drag forces in different flow regimes. since the nature of...