Previous investigations have shown that the size of a regurgitant jet as assessed by color Doppler flow mapping is independently affected by the flow rate and velocity (or driving pressure) of the jet. Fluid dynamics theory predicts that jet momentum (given by the orifice flow rate multiplied by velocity) should best predict the appearance of the jet in the receiving chamber and also that this ...

Thermal nuclear reactor power is typically evaluated with secondary system calorimetric calculations based on feedwater flow rate measurements. The feedwater flow rate should therefore be measured accurately. Venturi meters are currently used to measure the feedwater flow rate in most pressurized water reactors (PWRs). The long-term operation of a nuclear power plant causes a buildup of corrosi...

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...

Numerical investigation of gravity flow of granular solids in a hopper through orifices of different shapes has been conducted using the discrete element method. The simulations are validated by comparing with the experimental results for rapeseed cases. It is observed that with orifices of the same area the flow rate decreases in the order of circle, square, rectangle and triangle, which is si...

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 The purpose of the study was to develop and validate an automated method for calculating regurgitant flow rate using color Doppler echocardiography. BACKGROUND The proximal flow convergence method is a promising approach to quantitate valvular regurgitation noninvasively because it allows one to calculate regurgitant flow rate and regurgitant orifice area; however, defining the loc...

Analysis of velocity acceleration proximal to a regurgitant valve has been proposed as a method to quantify the regurgitant flow rate (Q.). Previous work has assumed inviscid flow through an infinitesimal orifice, predicting hemispheric isovelocity shells, with calculated flow rate given by QC=2rrN2vN, where VN is user-selected velocity of interest and rN is the distance from that velocity to t...