the multiple reference frames (mrf) method is the most suitable method tosimulate impeller rotation in mixing systems. precise determination of stationaryand moving zones in mrf method leads to accurate results in mixing performance.in this research, the entire volume of mixing system was divided into two zones.the kinetic energy values were used to distinguish the zones with differentvelocitie...

The behaviour of passive tracer particles in capillary Poiseuille flow is investigated with regard to the residence time in short axial sections of length z , in which z /a < Va/D, where a is the capillary radius, V is the mean velocity and D the coefficient of molecular diffusion. While methods exist for calculating moments of the crosssectionally averaged axial concentration distribution as a...

A new velocity profile equation for the description of microcirculatory blood flow in vivo was proposed in 2009. However various recently published papers still use the assumption of parabolic velocity profile (Poiseuille flow). The purpose of this work was to evaluate the performance of 3 different fitting cases: 1) best parabolic fit, 2) axial fit with the proposed equation and 3) best fit wi...

The influence of the inlet swirl velocity profile shape on the decay of swirl in steady-state, incompressible, laminar pipe flows is investigated by means of computational fluid dynamics. The investigation is carried out for a Reynolds number of 2000, which marks the upper limit of the laminar flow behavior for unidirectional pipe flow. Computations are performed for two different mean swirl nu...

Hydrodynamics analyses as a part of the APEX (advanced power extraction) study demonstrates the potential application of applying swirling thick liquid walls to innovative confinement concepts such as field reversed configuration (FRC), spherical torus (ST) and heavy-ion fusion (HIF). This paper addresses the design and the hydrodynamic aspects of fusion relevant swirling flow including 3-D vel...

This paper presents an experimental and numerical study of a pulsed air plasma discharge at atmospheric pressure propagating in a capillary glass tube. In this work, we have compared the discharge structures and the axial propagation velocities of discharges. First, we have studied a needle-to-plane configuration without tube. For applied voltages in the range 7 − 18 kV, we have observed in exp...

We propose a laser induced fluorescence heterodyne approach to resolve the timedependent ion velocity distribution (IVDF) in a Hall thruster. This approach is motivated by studies of low frequency modes of oscillations in Hall thruster, including azimuthal or so-called spoke and axial or so-called breathing oscillations. In this paper, we present the first successful application of this method ...

We report on progress towards the development of a Hall thruster simulation in the axial-azimuthal (z θ) computational space. Unlike most computational studies of closeddrift Hall accelerators which have been in one dimension (1D) along the axial direction or in two dimensions (2D) in the axial and radial dimensions, and which require some specification of the axial transport mechanism, this z ...

Direct numerical simulation was used to study the effect of controlled forcing at the jet nozzle on downstream mixing in a Mach 0.8 jet. The jet was forced by small slot jet actuators near the nozzle lip which blew normal to the initial jet shear layer and excited a flapping mode in the jet. The actuator jets and the nozzle itself were not explicitly simulated to spare the expense of including ...

The mechanism for band formation of a granular mixture in long rotating tumblers is unresolved 70 years after the phenomenon was first observed. We explore the onset mechanism for axial segregation of a bidisperse mixture of particles of different sizes using the discrete element method. End walls initiate axial band formation via an axial flow due to friction at the end walls. The nonuniform d...