Flow past the opening of a deep cavity can excite and sustain longitudinal acoustic modes resulting in large pressure fluctuations and loud tone generation. An analytic model of the interaction of the free stream with the acoustic flow field using concentrated vortices in the shear layer is proposed. The model includes a computation of the power transferred by the traveling vortices to the acou...

We present an improved effective action for the D-brane-anti-D-brane system obtained from boundary superstring field theory. Although the action looks highly nontrivial, it has simple explicit multi-vortex (i.e. codimension-2 multi-BPS D-brane) multianti-vortex solutions. The solutions have a curious degeneracy corresponding to different “magnetic” fluxes at the core of each vortex. We also gen...

Large-eddy simulations of pairs of artificially generated longitudinal vortices embedded in a two-dimensional turbulent boundary layer are performed to study the dynamics of the vortical structures and to provide the unsteady inflow data for use in a future turbomachinery simulation. An immersed boundarymethod is employed to represent the wall-mounted half-delta wings that generate the counter-...

We investigate the effects of topological defects (dislocations) to the ground state of the solid-on-solid (SOS) model on a simple cubic disordered substrate utilizing the min-cost-flow algorithm from combinatorial optimization. The dislocations are found to destabilize and destroy the elastic phase, particularly when the defects are placed only in partially optimized positions. For multi-defec...

A multi-year dataset of lidar measurements of polar stratospheric clouds (PSCs) from two sites in the Arctic (Sodankylä, 67°N, 27°E, and Ny-Ålesund, 79°N, 12°E) has been analyzed with respect to the existence temperature of different PSC types. Due to the location of the measurement sites relative to the polar vortex, their observations are most of the time representative of vortex edge and vor...

Vortex finder is a key part of cyclone separator. In the present study, multi-objective optimization of vortex finder is performed at three steps. At the first step, collection efficiency (η) and the pressure drop (∆p) in a set of cyclones with different vortex finder shape are numerically investigated using CFD techniques. Two meta-models based on the evolved group method of data handling (GMD...

Nontrivial topology of interfaces separating phases with opposite chirality in helical magnetic metals result in new effects as they interact with spin polarized current. These interfaces or vortex walls consist of a one dimensional array of vortex lines. We predict that adiabatic transfer of angular momentum between vortex array and spin polarized current will result in topological Hall effect...

The vortex of low speed flows is difficult to measure resulted in that the output signal of vortex flowmeter appears the spectral line splitting and frequency offset in the low SNR and causes the frequency resolution to be decreased. In the paper, it first conducted the multi-scale wavelet decomposition to the vortex signal with noise, then removed the noise spectrum and carried on power spectr...

We examine the transverse and longitudinal components of the drag force upon a vortex filament due to the scattering of liquid 4He excitations. For this purpose, we consider a recently proposed Hamiltonian that describes the dissipative motion of a vortex, giving an explicit expression for the vortexquasiparticle interaction. The involved dissipative coefficients are obtained in terms of the re...

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...