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Modelling of the Glass Press-Blow Process
Press-Blow Process of Glass
Press-blowing is a process that is commonly used in the glass industry to produce container glass (i.e., glass bottles and jars). The press-blow process consists of a pressing stage (1) and a blowing stage (2).
Initially the mould is open from above. Once a gob of glass is inside the mould, the mould is closed and the plunger moves upgradually. In this mould we obtain an intermediate form, the parison. This parison is transferred into a second mould, the blow mould, in which it is then blown into its final shape.
Important Characteristics of the Model
Glass can be considered as an incompressible fluid. The resulting momentum and mass conservation equations are
with μ the viscosity, v the velocity, Re the Reynolds number, Fr the Froude number, g the gravitational forces and p the pressure.
Pseudo Concentration Method
The Pseudo Concentration Method is used to define where glass and air are located. The concentration c is a continuous function with values between 0 and 1. c≥ 0.5 corresponds with glass and c<0.5 with air. Every timestep is transported by:
The viscosity now depends on the concentration:
where μglass depends on the temperature.
2D example to test the Pseudo Concentration Method.
The same test is performed on a (quarter of a) circle. For this problem there exists an analytical solution of the position of the inner interface. We compared this with the numerical results.
Analytically and numerically calculated radius r as function of time t.
The Pseudo Concentration Method seems suited for this problem, but needs some improvement. For instance (local) mesh refinements, or local modifications of the basisfunctions (Discontinuous Galerkin or Immersed Interface Method).
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