Finding Boundary Conditions: A Coupling Strategy for the Modeling of Metal Casting Processes: Part II. Numerical Study and Analysis

In Part II of this article, the experimental findings of Part I are incorporated into a numerical model to complete the coupling technique. Presenting the data in a generalized nondimensional form, the effect of surface roughness was observed to be pronounced at small relative gap sizes, reducing the heat transfer coefficient at least one order of magnitude below that predicted for perfectly flat surfaces. The effect was observed to progressively diminish with increasing gap sizes and approached an analytical "perfectly flat" solution for larger gap sizes. A simplified viscoelastic plastic numerical model was developed for a cylindrical coordinate system to predict the growth of the air gap. The modelʹs predictions of the gap growth compared well with the experimental measurements for each system examined. Application of the correlation via coupling with the energy equation was seen to improve the accuracy of an uncoupled casting model, bettering the predicted air gap formation and eliminating the previously existing time lag for initial formation of the gap.