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Dynamic behaviour
Published in Malcolm Millais, Building Structures, 2017
There are basically two types of collisions between objects, elastic collisions and inelastic collisions. In elastic collisions, the total momentum is conserved as is the total kinetic energy. In inelastic collisions, however, whilst the total momentum is still conserved, the kinetic energy – see page 407 – is not. Elastic collisions can be characterised by two idealised rigid spheres each having mass, velocity and direction that collide head on. After the collision, depending on the numerical values, the two spheres will have changed velocity and possibly direction – see Fig. 15.51.
Computer Visualization of Dynamic System Motion
Published in Naim A. Kheir, Systems Modeling and Computer Simulation, 2018
Collision is another important aspect of motion dynamics consideration. Elastic collision (kinetic energy is conserved) and inelastic collision (momentum is conserved, instead of the kinetic energy), coefficients of restitution, and insertion of stiff spring and damper constraints between colliding points are different forms of collision dynamics needed to be addressed in the models.
Kinetics in Linear Motion
Published in Emeric Arus, Biomechanics of Human Motion, 2017
A collision in which the total kinetic energy after the collision is less than that before the collision is called an inelastic collision. To be more explicit, the body or bodies will change their physical shape. Example includes a car crash or when two bodies stick together after the collision, for example, a sticky material thrown against the wall.
Characterization of soybeans and calibration of their DEM input parameters
Published in Particulate Science and Technology, 2021
Thiet Xuan Nguyen, Lu Minh Le, Thong Chung Nguyen, Nguyen Thi Hanh Nguyen, Tien-Thinh Le, Binh Thai Pham, Vuong Minh Le, Hai-Bang Ly
In order to relate the kinetic energy of two objects after collision, the coefficient of restitution was introduced as the ratio of the relative velocity after collision to the relative velocity before collision (Louge and Adams 2002; Weir and McGavin 2008). The coefficient of restitution is normally in the range of [0, 1] due to initial kinetic energy being lost to rotational energy, deformation and heat (Louge and Adams 2002; Hastie 2013). A coefficient of restitution of 1 exhibits a perfect elastic collision, whereas a perfect inelastic collision is characterized by a coefficient of 0 (Cross 1999). For agricultural granular materials, the restitution coefficients can be measured using grain-dropping tests (Gong, Zeng, and Qi 2019; LoCurto et al. 1997) or the double pendulum method (Hlosta et al. 2018). In this study, the coefficients of restitution between the soybeans themselves and between the soybeans and material surface were obtained by calibration using DEM simulation.
Simulation study of the effect of the restitution coefficient on interphase heat transfer processes and flow characteristics in a fluidized bed
Published in Numerical Heat Transfer, Part A: Applications, 2019
Hamada Mohamed Abdelmotalib, Ik–Tae Im
The collision of solid particles has a great effect on the operation of a fluidized bed reactor. This effect can be characterized using the particle–particle restitution coefficient. The value of the coefficient of restitution can range from zero for a fully inelastic collision to 1 for a fully elastic collision. The present study investigated the effect of the collision elasticity represented by the restitution coefficient on particle–particle and gas–particle heat transfer processes, as well as the relevant bed hydrodynamics. A 2D and a two-phase model of a fluidized bed reactor were used in our simulations study. Two different materials, sand particles and steel beads, were used as bed materials fluidized by air. We investigated the heat transfer between the bed materials and the fluidized gas, as well as the heat transfer between the solid particles. Increasing the collision elasticity resulted in increasing the bed pressure drop and decreasing the granular temperature, solid velocity, and collision frequency. The interphase heat transfer process, including interparticle and gas–particle heat transfer processes, decreased with increasing collision elasticity (i.e., with increasing the particle–particle coefficient of restitution). Sand particles showed better fluidization and heat transfer rates than the steel beads. The simulations results indicated that both the particle–particle and the gas–solid heat transfer processes strongly depended on the bed flow hydrodynamics, especially the void fraction and solid particles velocity.