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 ...

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...

Making use of φ-mapping topological current method, we discuss the self-dual vortices in the Abelian Chern-Simons model with two complex scalar fields. For each scalar field, an exact nontrivial equation with a topological term which is missing in many references is derived analytically. The general angular momentum is obtained. The magnetic flux which relates the two scalar fields is calculate...

Vortex methods for slightly viscous three-dimensional flow are presented. Vortex methods have been used extensively for two-dimensional problems, though their most efficient extension to threedimensional problems is still under investigation. A method that evaluates the vorticity by exactly differentiating an approximate velocity field is applied. Numerical results are presented for a flow past...

The vortex system in a high-Tc superconductor has been studied numerically using the mapping to 2D bosons and the Path Integral Monte Carlo method. We find a single first-order transition from an Abrikosov lattice to an entangled vortex liquid. The transition is characterized by an entropy jump of ∆S ≈ 0.27kB per degree of freedom and a Lindemann number cL ≈ 0.29. At low fields, λ ≈ a0, the den...