Numerical Simulation of Steady Two-dimensional Laminar Flow through a Duct with 90° Bend

摘要

Flow through a duct is an important field of study in fluid mechanics. Ducts having bends deserve special mention in this context. The literature appears to be rich in the experimental and theoretical studies of three-dimensional flow through square and rectangular channels with 90° bends. In some cases, ducts having circular or elliptical cross-sections were also studied. But the simpler case of the analysis of two-dimensional bend does not appear to have attracted much attention. In so far as industrial interest is concerned, it can be found that the two - dimensional duct analysis can supplant a three dimensional simulation in many situations. In the first phase of the present work, the limit of the applicability of two-dimensional flow through a 90° bend has been studied numerically. This limit has been established in terms of Dean Number. Finite element technique has been used for establishing the said limit. The pumping work has also been investigated in relation to Dean number. Subject to establishing the limit of the applicability of two-dimensional flow analysis, in the next phase of the work, streamline patterns and pressure distributions along the walls, under varied bend radii have been analyzed through numerical experiments. The effect of inlet length on the wall pressure distribution, and the influence of Dean number and bend radius on the length of influence zone have also been addressed in this paper.