‪Impulse wave generation: a comparison of landslides of block and granular masses by coupled Lagrangian tracking using VOF over a set mesh

This paper presents the numerical results of impulsive waves generated by landslides of solid block, granular materials and heavy block sinking. An impulse product parameter P is developed and a wide range of effective parameters are studied. The volume-of-fluid (VOF) and overset mesh methods have been used to study landslide-generated tsunamis. Also, a Lagrangian tracking approach coupled with the VOF to simulate the granular movement. The effect of the water reservoir depth, the landslide height, the landslide density and the geometrical parameters on the wave height (elevation) has been investigated using the open-source OpenFOAM software. The results have been presented for dimensionless distances and the normalized geometry of the landslide in the range 5–7, 1–2, respectively. These numbers have been normalized the height of the landslide (a). According to the results of simulations, the tsunami formation process is divided into three stages, which were analyzed in detail by considering the interactions between the solid and the water reservoir. The Scott Russell wave has the highest impulse product parameter among the impulse wave mechanisms which is 58.6% of the total impulse production. In addition, the duration of the wave propagation has been computed based on the wave height.

Micro/Nano-Particle Deposition in the Airway of a 6-Year-Old Child From Nostril to the Third Generation

In the present study the transport and deposition of micro/nano-particles in the airway model of a 6 year-old girl was investigated. The realistic airway model includes the nasal cavity, larynx, pharynx, trachea and also bronchial airways up to third generations. This model was developed from a series of high resolution CT scan images. For low to moderate activities, the steady airflows through the entire model of the child’s upper airway passages were simulated. Micro particle trajectories and deposition in the range of 1–30 μm were evaluated using a Lagrangian tracking approach and Eulerian method was used to assess the deposition rate of the nano-particles in the range of 1–150 nm. The deposition of micro and nano-particles in the airway of a child was evaluated and the results were with those for the adults and the differences were discussed. As was expected, a higher breathing resistance was observed for the 6-year-old child compared to adults, which leads to a higher particle deposition rate. The results of this study for the flow field and micro/nano-particle deposition showed the important differences between children and adults. Therefore care should be given to reduce the risk of airborne toxicants on infants and children.

Simulation of Particle Trajectories and Erosion Through a Centrifugal Compressor

Under particulate environments, turbocompressors suffer from erosion which is of serious concern to both manufacturers and users of these equipments. In this paper, the results of a numerical study of particle laden air flows through a radial compressor ‘Schwitzer’ are presented. Particle trajectories used an updated version of our in-house code based on a stochastic Lagrangian tracking approach, where equations of particle motion are solved separately from the air-stream. This latter considers the effects of turbulence on particles, initial locations of particles and random particle size and rebound. The tracking of particles in different computational cells and theirs corresponding impacts used the finite element method. The number of particles, their sizes and initial positions were specified according to a concentration profile and an AC coarse (0–200 micron) size distribution. The simulations results are depicting that the impeller rotating speed and particle size strongly affect the trajectories, locations of impacts and erosion rates. For a high rotational speed, erosion is spreading over the pressure side of the main blade and splitter. Regions of high erosion rates are seen on the blades leading edges and towards the upper corner at blade exit. However, the main blade is highly eroded than the splitter. The suction side is almost without erosion except near the leading edge. Furthermore, the casing is mainly affected over the inducer and along the tips of blades.