Cardiac MR group Lund, Dept. of Clinical Physiology, Lund University, Lund, Sweden Full list of author information is available at the end of the article Figure 1 Design and construction of the vortex ring flow phantom. a) 2D view of the flow rectifier and vortex ring tank. All measures are in millimeters (mm). b) 3D view of the flow rectifier and vortex ring tank. c) Pump design. A servo motor...

The deposition stability and homogeneity of microparticles improved with mask, lengthened nozzle and flow rate adjustment. The microparticles can be used to encapsulate monomers, before the monomers in the microparticles can be deposited onto a substrate for nanoscale self-assembly. For the uniformity of the synthesized nanofilm, the homogeneity of the deposited microparticles becomes an import...

This paper describes features in the structure of a laminar vortex ring ejected vertically from an elevated pipe into a uniform horizontal cross flow. Measurements are obtained by particleimage velocimetry (PIV) and flow-visualisation images are obtained by planar-laser-induced fluorescence (PLIF). Cross flow produces a shear layer over the open end of the elevated pipe. As a vortex ring is eje...

Compact zero-mass pulsatile jet actuators are proposed for low speed maneuvering, ducking, and station keeping of small underwater vehicles. To this end, optimization of synthetic jets for maximal thrust generation is investigated. Flow field of such jets are initially dominated by vortex ring formation. Pinched-off vortices characterize the extremum impulse accumulated by the leading vortex ri...

An axi-symmetric and swirling vortex sheet is investigated as the simplest ow in which there is non-trivial vortex stretching and as a possible setting for studying vortex cancellation and singularity formation. Rayleigh's criterion indicates linear stability of a single sheet but instability for other conngurations of sheets. Due to the simplicity of vortex sheet problems, the linear modes and...

An axisymmetric vortex-sheet model is applied to simulate an experiment of Didden (1979) in which a moving piston forces fluid from a circular tube, leading to the formation of a vortex ring. Comparison between simulation and experiment indicates that the model captures the basic features of the ring formation process. The computed results support the experimental finding that the ring trajecto...

Background Efficient right ventricular (RV) pumping function requires optimal blood flow dynamics. In the left ventricle (LV), diastolic vortex ring formation distal to the mitral valve (MV) has been reported to be an important mechanism for such blood flow optimization. Earlier work based on computational fluid dynamics (CFD) simulations using simplified RV geometry modeling have reported vort...

Cephalopods, among other marine animals, use jet propulsion for swimming. A simple actuator is designed to loosely mimic pulsatile jet formation in squid and jellyfish. The actuator is comprised of a cavity with an oscillating diaphragm and an exit orifice. Periodic oscillation of the diaphragm results in the formation of an array of vortex rings and eventually could generate a periodic pulsati...

Laboratory experiments indicate that an advancing ejecta curtain displaces the atmosphere and creates strong winds that entrain large amounts of fine-grained ejecta. A theoretical model describing the interaction between an atmosphere and the outward moving ejecta curtain allows one to estimate the magnitude and velocity of the winds in the induced ring vortex in order to establish the importan...

Vortex rings are one of the fundamental flow structures in nature. In this paper, the generation of circulation and vortex rings by a vortex generator with a static converging conic nozzle exit is studied numerically. Conic nozzles can manipulate circulation and other flow invariants by accelerating the flow, increasing the Reynolds number, and by establishing a two-dimensional flow at the exit...