This article investigates through experiments the flow characteristics of plane jets from sharp-edged orifice-plate, beveled-edge and radially contoured nozzle. The first two configurations exhibit saddle-backed velocity profiles while the third shows a top-hat. A vena contracta is found for the jet emanating from orifice at x/h ≈ 3 while the contoured case displays a potential core extending t...

Analysis of velocity acceleration proximal to a regurgitant valve has been proposed as a method to quantify the regurgitant flow rate (Qo). Previous work has assumed inviscid flow through an infinitesimal orifice, predicting hemispheric isovelocity shells, with calculated flow rate given by Qc = 2 pi rN2vN, where vN is user-selected velocity of interest and rN is the distance from that velocity...

The use of direct write micro-printing for opto-electronic packaging is being accepted as a key enabling technology, specifically printing microlenses for optical interconnects and solders for electrical interconnects. This paper presents these two areas where micro-printing technology benefits opto-electronic packaging . For increasing light coupling efficiency, a microlens array is actively a...

As part of an effort to develop efficient hollow cathodes for the International Space Station and low power electric propulsion systems, the effects of orifice length-to-diameter aspect-ratio on the performance of 0.5 to 2 A hollow cathodes were examined to compare with previous experiments and a recently developed model. Cathodes were constructed with nominally identical orifice diameters and ...

Background Due to the nature of the percutaneous prosthesis deployment process, a variation in its final position is expected. Prosthetic valve placement will define the spatial location of its effective orifice in relation to the aortic annulus. The blood flow pattern in the ascending aorta is related to the aortic remodeling process, and depends on the spatial location of the effective orific...

Objectives. In this study we Investigated the centerline velocity profile method for low computation applied to noncircular, as well as circular, orifices using digital color Row data . Ractlgroaud. Recently it been fed that low volume thrmo an orifice can be estimated more accurately by computing the axial "centerline" low velocityldistance profile proximal to the orifice. etha'. A total of se...

Background. Although Doppler echocardiography has been shown to be accurate in assessing stenotic orifice areas in native valves, its accuracy in evaluating the prosthetic valve orifice area remains undetermined. Methods and Results. Doppler-estimated valve areas were studied for their agreement with catheterderived Gorlin effective orifice areas and their flow dependence in five sizes (19/20-2...

OBJECTIVES We used the Doppler proximal flow convergence technique as a physiologic tool to explore the effects of the time courses of mitral annular area and transmitral pressure on dynamic changes in regurgitant orifice area. BACKGROUND In functional mitral regurgitation (MR), regurgitant flow rate and orifice area display a unique pattern, with peaks in early and late systole and a midsyst...