Comparison of four methods to evaluate fluid velocities in a continuous slab casting mold

Four different methods are compared for evaluating fluid flow velocities in the liquid pool in the mold region of a continuous caster of steel slabs. First, the instantaneous and time-averaged flow pattern in a 0.4-scale wate r model with single-phase flow is quantified using particle image velocimet ry (PIV). Next, three-dimensional computations are performed to calculate t he time-average flow pattern in the same system using a conventional finite -difference program, CFX, with the conventional K-epsilon model for handlin g turbulence. Transient computations are then performed using a 1.5-million node grid to resolve the turbulent eddies, both without a turbulence model (direct numerical simulation: DNS) and with a subgrid scale model (large e ddy simulation: LES). Finally, measurements are obtained using electromagne tic sensors embedded in the mold walls of an operating steel slab casting m achine. The comparisons reveal remarkable quantitative agreement between al l four methods for the overall time-averaged flow pattern and surface veloc ities for these conditions. The time-averaged K-epsilon model is capable of accurate quantitative calculations of the steady flow field with the least effort, but has difficulty with transient behavior. The LES model predicts both steady and transient phenomena, but has severe computational cost, Wa ter models with PIV are useful and practical tools, but are difficult to ex tend beyond the flow pattern to practical phenomena, such as heat transfer, solidification, surface slag entrainment, two-phase flow, and particle mot ion. The electromagnetic sensor has the advantage of measuring the real pro cess, but is computed to be accurate only where the flow is roughly uniform and directly horizontally between the two probes, so is limited to measuri ng average speed at just a few points. Thus, each method has its own merits and disadvantages relative to the others, and can be a useful tool for inv estigating flow phenomena in processes with molten metal. Together, these m ethods reveal new insights into steady and transient flow in the continuous slab-casting mold, which are discussed in this work.