The Creare one-fifth-scale Phase II experiments, which model fluid and thermal mixing of relatively cold high-pressure injection water into a cold leg of a full-scale pressurized water reactor having loop flow, are analyzed. It is found that they cannot achieve complete similarity with respect to characteristic Reynolds and Froude numbers and developing hydrodynamic entry length. Several analyses show that these experiments fall into two distinct regimes of mixing: momentum and gravity controlled (stratification).