Finding boundary conditions: A coupling strategy for the modeling of metalcasting processes: Part II. Numerical study and analysis

In Part II of this article, the experimental findings of Part I are incorpo rated into a numerical model to complete the coupling technique. Presenting the data in a generalized nondimensional form, the effect of surface rough ness was observed to be pronounced at small relative gap sizes, reducing th e heat transfer coefficient at least one order of magnitude below that pred icted 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 num erical model was developed for a cylindrical coordinate system to predict t he growth of the air gap. The model's predictions of the gap growth compare d well with the experimental measurements for each system examined. Applica tion of the correlation I in 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 ini tial formation of the gap.