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H. Schoosleitner, D. Trauner: 
''Modellierung und Untersuchung der Str{\"o}mung durch die R{\"u}ckstromsperre eines Schraubenverdichters''; 
Supervisor: B. Scheichl; Institute of Fluid Mechanics and Heat Transfer, 2017; final examination: 2017-10-24.

@mastersthesis{schoosleitner17[TUW-262292],
    author = {Schoosleitner, Herbert and Trauner, Daniel},
    title = {Modellierung und Untersuchung der Str{\"o}mung durch die R{\"u}ckstromsperre eines Schraubenverdichters},
    school = {Institute of Fluid Mechanics and Heat Transfer},
    year = {2017},
    keywords = {back-flow barrier, extruder screw, glas fibres, lubrication theory, mixed friction, polymer melt, shear-thinning},
    abstract = {\par
 This thesis investigates the flow of a glass fibres carrying polymer melt through a back ow barrier of a screw extruder, which is vigorously coupled with the temperature field. The polymer melt behaves non-Newtonian, the interplay between the equations of motion and the thermal heat equations therefore originates from the viscosity's strong dependence on the rate of shear and temperature. In addition, the relative rotational velocity of the locking ring and the screw causes another interdependency, since shear forces of the flow and friction forces between ring and wings of the screw severely affect the ring's number of revolutions. This mixed friction is modelled as a combination of hydrodynamic and dry friction. The mean length and diameter of the glass fibres are used to characterize thefriction coeffcient's dependency on the gap width between the ring's face and the wings. \par
 By means of dimensional analysis and appropriate assumptions, the fundamental equations are developed until finally a specially designed iterative algorithm offers a numerical solution of the coupled system. The system of equations describes the behaviour of heat transfer and fluid motion until a steady state is reached and the locking ring features constant angular velocity. Time-dependent solutions are presented. \par
 The disparate time scales, which are characterized by the central equations of the problem, play an essential role in describing the transient phase. They provide information on the chronological sequence of heat transfer and relaxant fluid motion by virtue of altered thermal conditions. This strategy can be extended towards a complete multiple scaling. \par
}
}