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Three-dimensional Flow Analysis of the Oldroyd-B Fluid through an Abrupt Contraction
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Wen, Hongzhao / Nakamura, Kiyoji
The flow of the Oldroyd-B fluid in a 3-D abrupt contraction was computed using the HSMAC method. Numerical results show that two stable flow regions exist upstream from the 3-D abrupt contraction. One is a vortex growth region, which is present at low Reynolds number Re and high Weissenberg number We. The vortex region is three-dimensional, and grows with increasing We. In the upstream corner of the abrupt contraction, along the edge of the salient corner the flow direction is in reverse at small We, and a secondary flow appears near the edge, which develops to form a larger vortex region with increasing We. It is concluded that the secondary flow along the edge of salient corner is responsible for vortex enhancement in the 3-D abrupt contraction flow. The second stable flow region is a spiralling flow region as shown in Fig. 6 and 7, which can occur at high Reynolds number and low Weissenberg number. The secondary flow region shrinks at Re < 30, and grows at Re > 30 with increasing Re.
Key words: 3-D contraction flow / HSMAC method / Oldroyd-B fluid