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	Simulation of saltation motion using LBE based methods Dolanský, Jindřich The numerical model of the motion of the circular particle close to the bed in an open channel with a rugged bed based on the lattice Boltzmann method (LBM) is presented. The LBM is used as a DNS approach in which hydrodynamic forces are expressed as sum of contributions from fluid elements interacting with the moving particle. The corresponding numerical simulation for the saltation motion which represents a dominant mode of the bed load transport is developed. Flow is driven by the logarithmic velocity profile at the inlet of a two dimensional channel with a bed formed by semi-circles of variable radii in a bed of particles. Translational and rotational movements of the particle are induced by gravitational force on one hand, and by hydrodynamic forces on the other hand. The LBE (lattice Boltzmann equation) based simulation provides the opportunity to study the behavior of saltation motion in the moderate and high Reynolds number regimes. Most of the input parameters, including boundary conditions or flow conditions, are adjustable within a range of values. Stability issues of the simulation are considered and a resolution using a combination of different LBE models and the extension of computational resources is proposed. Finally, an enhancement of the simulation for more complex processes is suggested. Detailed record
	Zahájení pohybu dnových sedimentů v režimu saltace Kharlamov, Alexander ; Chára, Zdeněk ; Vlasák, Pavel The paper deals with dependence of threshold shear stress on Reynolds number for saltation mode of bed load transport. The incipient of particle saltation in turbulent flow was determined and presented in variables introduced by Shields. For the condition of the threshold there was chosen the equality of the submerged gravitational force and the lift force on a bed particle. An additional dimensionless parameter ξ characterizing the bed surface formation was introduced. The critical shear stress as function of bed particle Reynolds number was determined analytically and reported in graphical form for different values of the bed parameter. The calculated values of an introduced parameter ξ characterising bed formation differ from results of Ling (ξ=3) and approximately agree with experimental results of Ancey et al. (ξ=2/3).The obtained results agree with available experiments on saltation start. Detailed record
	Numerický model saltace kulovité částice v kanále s příčně skloněným drsným dnem Lukerchenko, Nikolay ; Piatsevich, Siarhei ; Chára, Zdeněk ; Vlasák, Pavel The paper deals with 3D numerical model of the spherical particle saltation in the rectangular channel with rough bed and the effect of lateral slope of the bed. The stochastic method based on the concept of contact zone is used for the calculation of particle-bed collision. Some examples of calculation are presented, in particular, the effect of transverse tilted bed on the particles sorting. The beams of the trajectories of particles starting saltation from one point are calculated. The centrelines of the beams can be approximated by straight lines for low and moderate values of the bed transverse slope and the angles between centrelines and the stream direction depend on the lateral slope of the bed. Detailed record

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