the first step in studying dust events is the estimation of dust emission from sources. in this study, the simulations of the vertical dust flux (vdf) over iran by the mba (marticorena, bergametti, and alfaro) and shao schemes are compared. the mba scheme is energy-based and derived on the basis of energy balance between the kinetic energy of saltating particles and binding energy of the surfac...

this research includes both experimental and cfd investigation in the hydrodynamic behavior of a new type of column tray introduced as “concap” tray. the proposed column tray is used in contactor columns especially in stripping columns. the hydrodynamics of this concap tray is investigated in a 1.2m in diameter column. using air-water system, the experiments were performed for different liquid ...

We used a pulsed Doppler technique to examine the flow velocity pattern in the right ventricular outflow tract in 33 adults. In the patients with normal pulmonary artery pressure (mean pressure less than 20 mm Hg, 16 patients), ejection flow reached a peak level at midsystole (137 +/- 24 msec, mean +/- SD), producing a domelike contour of the flow velocity pattern during systole. In contrast, t...

We present and study a stabilized mixed finite element method for single-phase compressible flow through porous media. This method is based on a pressure projection stabilization method for multiple-dimensional incompressible flow problems by using the lowest equal-order pair for velocity and pressure i.e., the P1 − P1 pair . An optimal error estimate in divergence norm for the velocity and sub...

The peak pressure drop across the aortic valve in aortic stenosis has been measured by Doppler ultrasound. Maximum velocity in the Doppler signal from the aortic jet was recorded using a maximum frequency estimator. With an angle close to zero between ultrasound beam and maximal velocity in the jet, peak pressure drop can be calculated from the maximal velocity measured; a larger angle will und...

Instantaneous contractile element velocity was calculated from left ventricular pressure and its first derivative during isovolumic left ventricular contractions produced by sudden balloon occlusion of the ascending aorta during diastole in closed-chest, sedated dogs. Wall tension was derived from ventricular pressure and volume, the latter being obtained from the pressure-volume relation of th...

In this paper, we introduce a new and efficient way to compute exactly divergence free velocity approximations for the Stokes equations in two space dimensions. We begin by considering a mixed method that provides an exactly divergence-free approximation of the velocity and a continuous approximation of the vorticity. We then rewrite this method solely in terms of the tangential fluid velocity ...

Background. While flow convergence methods have been promising for calculating volume flows from color Doppler images, it appears that the velocity threshold used and the transorifice pressure gradient dramatically influence the accuracy of application of the simple hemispheric flow convergence equation for calculation of flow rate. The present in vitro study was performed to determine whether ...

We present Helmholtz or Helmholtz like equations for the approximation of the timeharmonic wave propagation in gases with small viscosity, which are completed with local boundary conditions on rigid walls. We derived approximative models based on the method of multiple scales for the pressure and the velocity separately, both up to order 2. Approximations to the pressure are described by the He...

In this paper, the methodology of aircraft air distribution system has been analyzed theoretically and experimentally. To achieve that, ducting pressure loss and air flow throw gaspers calculations has been done for cabin ducts in according to exact location of individual air distribution system in the cabin. The length of gasper air flow was compared with the distance between gasper outlet and...