Numerical analysis of submarine landslides using a smoothed particle hydrodynamics depth integral model

Submarine landslides can cause severe damage to marine engineering structures. Their sliding velocity and runout distance are two major parameters for quantifying and analyzing the risk of submarine landslides.Currently, commercial calculation programs such as BING have limitations in simulating underwater soil movements. All of these processes can be consistently simulated through a smoothed particle hydrodynamics（SPH） depth integrated model. The basis of the model is a control equation that was developed to take into account the effects of soil consolidation and erosion. In this work, the frictional rheological mode has been used to perform a simulation study of submarine landslides. Time-history curves of the sliding body＇s velocity, height,and length under various conditions of water depth, slope gradient, contact friction coefficient, and erosion rate are compared; the maximum sliding distance and velocity are calculated; and patterns of variation are discussed.The findings of this study can provide a reference for disaster warnings and pipeline route selection.

Experimental study on influence of blade angle and particle size on particle mechanics on a batch-operated single floor of a multiple hearth furnace

In industry,multiple hearth furnaces are used for the thermal treatment of particulate material.The current contribution concentrates on the experimental analysis of particle mechanics for a batch-operated single floor of a multiple hearth furnace.The particles are agitated on the circular floor by a single,rotating rabble arm equipped with three flat rabble blades of 10 mm thickness.The blade angle,defined as the angle,which the blade is inclined against the tangential direction,is varied from 0°to 90°.A single layer of spherical polyoxymethylene(POM)particles with three different diameters(5,10 and 20 mm)is placed on the floor.To analyze the results,two parameters have been extracted from image analysis when the bed of particles is agitated,first,the area not covered by particles and second,the frequency distribution of the mean distance among the particles.The particle free surface area increases with the inclination of the blades.The evolution of the particle free surface area differs for the different particle diameters.In general,the maximum particle free area for all blade angles is the largest for the 5 mm particles followed by the 20 mm particles.For the 10 mm particles,the particle free surface area starts for a blade angle of 0°at larger values than for the 20 mm particles but the values fall below the values for the 20 mm particles for larger blade angles.The reason for this behavior is discussed in detail.The mean distance among the particles is a parameter characterizing the length scales dominating the effects on the floor.The frequency distribution of the mean distance among particles provides infor-mation about the morphology of the particle bulk,for example,whether the free surface area is inter-spersed with particles.

Particle Scale Numerical Simulation on Momentum and Heat Transfer of Two Tandem Spheroids:an IB-LBM Study

The cold fluid flowing over two hot spheroids placed in a tandem arrangement was numerically studied via a GPU-based immersed boundary-lattice Boltzmann method(IB-LBM)model.The drag coefficient and average Nusselt number of both the two spheroids were obtained with the main influencing factors investigated.To validate the IB-LBM model,several numerical case studies containing one and two spheres were firstly conducted to reach the good agreement with the previously reported data.Then,a number of simulations were further carried out which were designed by changing the particle aspect ratio(1.0≤Ar≤4.0)and inter particle distance(1.5≤ι≤7.0,whereι=L/D,D stands for the volume-equivalent sphere diameter)as well as the Reynolds number(10≤Re≤200).Their influence on the momentum and heat transfer characteristics between the solid and fluid phases was fully discussed.Numerical results show that,for all the considered Reynolds numbers and aspect ratios,the individual and total drag coefficients and average Nusselt number increase with the inter particle distance.The inter particle distance has greater influence on the drag coefficient and average Nusselt number of the trailing particle than the leading one.The drag coefficient and average Nusselt number of the trailing particle are far less than the leading one under the same working conditions.The prediction correlations for the drag coefficient and average Nusselt number of both the two spheroids were established with low deviations.At last,the influence of the relative incidence angles between the two tandem spheroids on the momentum and heat transfer was studied.It is shown that the relative incidence angles play significant roles due to the change of the frontal area of the leading spheroid with these angles.

Capillary bridges and capillary forces between two axisymmetric power-law particles

Capillary interactions are fundamentally important in many scientific and industrial fields. However, most existing models of the capillary bridges and capillary forces between two solids with a mediated liquid, are based on extremely simple geometrical configurations, such as sphere-plate, sphere-sphere, and plate-plate. The capillary bridge and capillary force between two axisymmetric power-law profile particles with a mediated constant-volume liquid are investigated in this study. A dimensionless method is adopted to calculate the capillary bridge shape between two power-law profile particles based on the Young-Laplace equation. The critical rupture criterion of the liquid bridge is shown in four forms that produce consistent results. It was found that the dimensionless rupture distance changes little when the shape index is larger than 2. The results show that the power-law index has a significant influence on the capillary force between two power-law particles. This is directly attributed to the different shape profiles of power-law particles with different indices. Effects of various other parameters such as ratio of the particle equivalent radii, liquid contact angle, liquid volume, and interparticle distance on the capillary force between two power-law particles are also examined.