Flow Past a Hybrid Cylinder Composed of Half Diamond and Semicircular Cylinders

Abstract

Numerical investigation of a two-dimensional, laminar, incompressible flow past a hybrid cylinder is performed for Reynolds number in the span of 5 ≤ Re≤ 150. The hybrid cylinder is generated by combining half of the cross-sections of a diamond cylinder and a circular cylinder. A stabilized finite-element technique is utilised to discretize the Navier-Stokes equations in two-dimensions. Several flow parameters such as, aerodynamic coefficients, surface pressure distribution, wake length, separation angle, Strouhal number, etc and flow pattern via streamlines are analyzed with Reynolds number in the steady and unsteady regimes of flow. The steady flow is investigated for 5 ≤ Re≤ 40. It is observed that with increase in Re, eddy length and separation angle both increase. It is found that the initial separation occurs at Re=5.6. For the unsteady flow over 60 ≤ Re≤ 150, it is noticed that the eddy length decreases non-linearly while the separation angle increases with Re. Time-averaged streamlines are also shown at certain various Reynolds numbers. Comparison of various characteristics flow quantities for the circular, diamond, square and circular cylinders is done and it is observed that the trends are similar for all three cases.