Surface growth effects on reactive capillary-driven flow: Lattice Boltzmann investigation

TL;DR

This study uses the Lattice Boltzmann method to investigate how surface reactions and deformation affect capillary-driven flow in narrow pores, revealing pore closure independence from infiltration velocity and optimal pore geometries for faster infiltration.

Contribution

It introduces a detailed LB simulation framework for reactive infiltration in capillaries, highlighting the impact of surface growth and geometry on flow behavior, which was not previously well understood.

Findings

Pore closure is independent of infiltration velocity.

Short, wide, round pores facilitate faster infiltration.

Surface reaction and geometry critically influence flow dynamics.

Abstract

The Washburn law has always played a critical role for ceramics. In the microscale, surface forces take over volume forces and the phenomenon of spontaneous infiltration in narrow interstices becomes of particular relevance. The Lattice Boltzmann method is applied in order to ascertain the role of surface reaction and subsequent deformation of a single capillary in 2D for the linear Washburn behavior. The proposed investigation is motivated by the problem of reactive infiltration of molten silicon into carbon preforms. This is a complex phenomenon arising from the interplay between fluid flow, the transition to wetting, surface growth and heat transfer. Furthermore, it is characterized by slow infiltration velocities in narrow interstices resulting in small Reynolds numbers that are difficult to reproduce with a single capillary. In our simulations, several geometric characteristics for the capillaries are considered, as well as different infiltration and reaction conditions. The main result of our work is that the phenomenon of pore closure can be regarded as independent of the infiltration velocity, and in turn a number of other parameters. The instrumental conclusion drawn from our simulations is that short pores with wide openings and a round-shaped morphology near the throats represent the optimal configuration for the underlying structure of the porous preform in order to achieve faster infiltration. The role of the approximations is discussed in detail and the robustness of our findings is assessed.