Axisymmetric and nonisothermal inflation of fluid annular menisci under an imposed pressure gradient is analyzed by solving the unsteady momentum and energy conservation equations coupled with an appropriate constitutive expression, and subject to kinematic, dynamic and heat transfer boundary conditions. Numerical calculations combine Galerkin/finite element discretization with a fully-implicit time integration algorithm. This procedure simultaneously determines the flow field and temperature distribution within the meniscus together with the moving surfaces at every time step. Dynamic simulations of the inflation process verify and extend the conclusions reached from an equilibrium stability analysis, and they indicate that the presence of a confining wall has a stabilizing effect on the inflation process. Nonisothermal calculations show that the inflation rate is increased as a result of higher temperature within the meniscus; but, the instantaneous shape and final thickness distribution upon wall contact remain virtually identical to the isothermal results. The critical factor during inflation is the temperature distribution within the meniscus that could arise as a result of its uneven cooling prior to inflation. Due to the temperature dependence of the physical properties, hotter regions of the material deform at a faster rate than cooler regions and the thickness of the inflated part is affected. Inflation of the meniscus that results in full attachment to a confining mold wall takes only a small fraction of the time required to cool the material down to the ambient gas temperature. The results of the present study illustrate how computer simulations may be used as a design tool for the blow molding process, and they show good agreement with available experiments.
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