Multiscale Simulation of Non-Metallic Inclusion Aggregation in a Fully Resolved Bubble Swarm in Liquid Steel

Abstract

Removing inclusions from the melt is an important task in metallurgy with critical impact on the quality of the final alloy. Processes employed with this purpose, such as flotation, crucially depend on the particle size. For small inclusions, the aggregation kinetics constitute the bottleneck and, hence, determine the efficiency of the entire process. If particles smaller than all flow scales are considered, the flow can locally be replaced by a plane shear flow. In this contribution, particle interactions in plane shear flow are investigated, computing the fully resolved hydrodynamics at finite Reynolds numbers, using a lattice Boltzmann method with an immersed boundary method. Investigations with various initial conditions, several shear values and several inclusion sizes are conducted to determine collision efficiencies. It is observed that although finite Reynolds hydrodynamics play a significant role in particle collision, statistical collision efficiency barely depends on the Reynolds number. Indeed, the particle size ratio is found to be the prevalent parameter. In a second step, modeled collision dynamics are applied to particles tracked in a fully resolved bubbly flow, and collision frequencies at larger flow scale are derived.

Shear-Induced Heteroaggregation of Oppositely Charged Colloidal Particles

“…Before discussing on the population aggregation dynamics, it is useful to investigate how primary particles aggregate depending on their surface potentials. In fact, the complex interplay between hydrodynamic and colloidal interactions determines the aggregation efficiency of colloidal particles, − which, especially when starting from monomeric conditions, strongly affects the early stage of the aggregation process.…”

Evolution of Inclusions in Incoloy825 during Electroslag Remelting

“…Many researchers [36,37] have found that MgO-Al 2 O 3 has a high potential for acting as a TiN nucleation site because of the low disregistry. The existing form of Al 2 O 3 inclusions was Al 2 O 3 with a TiN layer in this study, which means that the formation of an inclusion of MgO-Al 2 O 3 surrounded by a TiN layer was from an inclusion of the Al 2 O 3 surrounded by a TiN layer, as shown in Equations ( 9)- (11). With regard to the MgO-Al…”

“…The obtained oxide inclusion in the electrode was Al 10), and the (MgO) in the inclusions appeared. Combining Equations ( 9) and (10), we can find that the (MgO) in the slag transformed into (MgO) in the inclusions through (Al 2 O 3 ), as shown in Equation (11), and the Gibbs energy was 0 [35]. Therefore, the inclusions of Al 2 O 3 transformed to a spinel solid solution.…”

“…Li et al [8] studied heating austenitic alloy at 1273 K and investigated the evolution of TiS and TiN inclusions. Several researchers [9][10][11] investigated the inclusions through simulation. Many researchers [12][13][14] reported that the inclusions in Ti-containing alloy and steel are related to the chemical composition and deoxidation.…”

Numerical investigation of the respective roles of cohesive and hydrodynamic forces in aggregate restructuring under shear flow

“…Complex dynamics arise in particle interactions at finite Reynolds number, even at values down to Re ∼ 10 −2 [53,54], that may have a significant impact on aggregate behaviour. The LBM as used in this research is well suited for finite Reynolds simulations, unlike SD.…”