Non‐Isothermal Simulations of Aluminum Depth Filtration

Abstract

The present article addresses the modeling issues, related to the numerical simulation of aluminum depth filtration inside a real filter section in presence of non-negligible temperature variation. The filter structure is obtained by digitizing the computed tomography (CT) scanned data of a characteristic ceramic foam filter. The modeling takes the process conditions of a filtration trial in a pilot casting line into account. The incompressible flow of liquid aluminum is solved by the lattice Boltzmann method (LBM) and the heat transfer is solved by the finite volume method (FVM). The temperature dependences of the viscosity and the density of liquid metal are specifically considered. Although the consideration of buoyancy force significantly affects the fluid flow, the temperature-dependent viscosity plays only a minor role. A Lagrangian tracking of particles is performed for modeling the filtration of inclusions. In accordance with the depth filtration theory, the computational results confirm an exponential decrease in the particle concentration with the filter depth. The overall filtration efficiency is found to remain almost unaffected by both buoyancy and temperature-dependent viscosity. Using the numerically determined filtration coefficient, the filtration efficiency is extrapolated for a real filter of larger length, although the experimental data are underpredicted.

Influence of Foam Morphology on Effective Properties Related to Metal Melt Filtration

“…For a detailed description of the numerical models, employed for this investigations, the reader may refer to Demuth et al [12,13] Therefore, only a short summary and additional details, specific to the present investigation, are provided here for the sake of brevity.…”

Numerical Modeling of Flow Conditions during Steel Filtration Experiments

“…All simulations are performed with periodic boundary conditions in all directions and assuming the no-slip condition at the filter walls, that is, on the strut surfaces, while the flow is considered to be driven by an imposed pressure gradient in the main flow direction (x-direction in Figure 3). Further information regarding the LBM, used for this investigation and www.advancedsciencenews.com www.aem-journal.com its implementation may be found in the article, presented by Demuth et al [28] …”

Experimental Investigations of the Depth Filtration inside Open‐Cell Foam Filters Supported by High‐Resolution Computed Tomography Scanning and Pore‐Scale Numerical Simulations

“…An Euler-Langrange framework has been adopted for modeling the fluid flow and particle trajectories, which was explained in detail by Demuth et al [6] and is therefore only briefly described here. In the model, the flow of water is assumed to be transient, incompressible, and isothermal and described by the corresponding conservation equations for mass and momentum.…”

“…In this context numerical methods are often used, although modeling of the filtration process is considerably challenging due to its complexity and hence several simplifying assumptions are invoked . The primary objective of all these approaches is to increase the filtration efficiency either by modifying the filter surface or by improving the filter geometry with respect to the flow characteristics and resistance to the melt flow.…”

“…[5] In this context numerical methods are often used, although modeling of the filtration process is considerably challenging due to its complexity and hence several simplifying assumptions are invoked. [6] The primary objective of all these approaches is to increase the filtration efficiency either by modifying the filter surface [7] or by improving the filter geometry with respect to the flow characteristics [8] and resistance to the melt flow. The present investigation on water-based model introduces the computed tomography as an important tool for characterization of particle separation inside CFF and provides detailed insight into the filtration efficiency for the first time.…”