The feeding-resistance porosity criteria functions proposed by Niyama et al., Lee et al., and Suri et al. are considered. All are rederived from first principles, and the derivations show that they all derive from the same physical reasoning and differ only in the treatment of the permeability of the mushy zone. These criteria are examined in detail in the present paper and in their most simplified form are used to predict porosity in aluminum A356 castings by correlating porosity data from independent sets of experiments. The role of hydrogen level in determining the degree of correlation is briefly discussed and recommendations or further experimental validation is presented.
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