A transient model for nozzle clogging – Part II: Validation and verification

Abstract Part I of this two-part work discusses a transient two-way coupling model for clogging of nozzle (fluid passage) due to deposition of suspended particles on the nozzle wall. The purpose of Part II is to validate and verify the model. To this end, the current model simulates a laboratory experiment, designed to study the clogging of a submerged entry nozzle (SEN) during steel continuous casting. It demonstrates that the model can reproduce the experiment satisfactorily: the numerically-calculated clogged section of the nozzle is qualitatively comparable with typically “as-clogged” sections in laboratory experiments; the calculated mass flow rate through the nozzle during clogging process as function of time is also in agreement with the experimentally-monitored result. The simulation-experiment agreement depends on parameters, e.g. mesh size, Lagrangian time scale, correction factor in interpolation of clog permeability, and porosity in the clog materials, which act as inputs for the numerical model. Uncertainties for choosing such parameters, model capabilities/limitations due to model assumptions have been studied and discussed in this paper. In this regard, further model refinements are suggested. The modeling results provide new knowledge about clogging behavior. (1) Clogging is a transient process, and it includes the initial coverage of the nozzle wall with deposited particles, the evolution of a bulged clog front, and then the development of branched structure. This transient growth of clog interacts with the flow. (2) Clogging is a stochastic and self-accelerating process.