Dilute liquid sprays can be modeled at the mesoscale using a kinetic equation, namely the Williams-Boltzmann equation, containing terms for spatial transport, evaporation and fluid drag. The most common method for simulating the Williams-Boltzmann equation uses Lagrangian particle tracking wherein a finite ensemble of numerical “parcels” provides a statistical estimate of the joint surface area...

We analyze the 1D velocity-jump process, where a particle moves at a constant velocity determined by the particle’s internal velocity state that randomly fluctuates with exponentiallydistributed waiting times. The transition rates between the internal velocity states depend on the location of the particle, leading to a spatially-inhomogeneous random process. An asymptotic analysis is applied to...

Deposition of sediment inside the conduit structures reduces the flow cross section area and increases the flow roughness which causes reduction of flow discharge passing through the conduit. Among the methods which can prevent sediment deposition is non sedimentation condition in the structure, Since the critical section of the inverted siphon in sedimentation is the outlet. In the begining of...

In the present study, we separated the marker particles from the suspending particle mixture solution using isotacho-electrophoresis technique, a novel quantitative ionic particle separation method, in the microchannel. A multiple stacking zone of the suspending particle was visualized with variations in electric field strength, pH value and concentration of the ionic solution. In particular, t...

Gas-phase velocity fluctuations in fixed particle beds and freely evolving suspensions are quantified using particle-resolved direct numerical simulation (PR-DNS). The flow regime corresponds to homogeneous gas-solid systems typically encountered in fluidized bed risers, with high solid to gas density ratio and particle diameter being greater than the dissipative length scales. The contribution...

Experiments were performed in a three-phase bubble column to study variations of bubble rise velocities. The dynamic gas disengagement (DGD) technique and the fast response pressure transducers were utilized to investigate the bubble rise in the column. The superficial gas velocity of large bubbles and small bubbles, the rise velocities of larger and small bubble fractions were studied consider...

During the past five years, significant progress has been made in the development and application of micron-resolution Particle Image Velocimetry (μPIV). Developments of the technique have extended typical spatial resolutions of PIV from order 1-mm to order 1-μm. These advancements have been obtained as a result of novel improvements in instrument hardware and post processing software. Theory d...

A cloud particle size retrieval algorithm that uses radar reflectivity factor and Doppler velocity obtained by a 35-GHz Doppler radar and liquid water path estimated from microwave radiometer radiance measurements is developed to infer the size distribution of stratus cloud particles. Assuming a constant, but unknown, number concentration with height, the algorithm retrieves the number concentr...

Computational fluid dynamics (CFD) and numerical investigations of particle inhalability and contaminant exposure have used simple geometrical surrogates for a breathing human form, but the effect of eliminating facial features has not been investigated. In this work, the velocity field and particle aspiration associated with two differently shaped mannequins were investigated to determine if a...

The first three moments of the millimeter-wavelength radar Doppler spectrum provide valuable information regarding both cloud properties and air motion. An algorithm using these Doppler radar moments is developed to retrieve cirrus microphysical properties and the mean air vertical motion and their errors. The observed Doppler spectrum results from the convolution of a quiet-air radar reflectiv...