To disclose the flow field features around a circular cylinder with rear diaphragm, this paper numerically simulates the effects of diaphragm length on the potential flow around such a circular cylinder, using the characteristic-based operator splitting (CBOP) method based on multi-step format (MSF). Through the simulation, the author obtained the flow field velocities, mean drag coefficient, lift coefficient and Strouhal number, and analysed the variation laws of the flow field features. The research shows that the addition of the rear transverse diaphragm can effectively suppress the vortex shedding in the wake region, reduce the pressure difference between the upper and lower surfaces of the circular cylinder, and greatly improve the flow around the circular cylinder. When the diagram length was sufficiently long, the vorticity of the upper and lower shear layers was completely dissipated during the backward movement along the transverse diaphragm, eliminating the occurrence of vortex shedding. The simulated laws of the flow velocities and flow field eigenvalues were consistent with the results of the previous studies. The research findings provide a valuable reference for similar studies in future.
finite-element analysis, rear diaphragm, potential flow around a circular cylinder, multi-step format (MSF), characteristic-based operator splitting (CBOP)
 Li QH, Liu GM, Xue K, Wang J, Wang P. (2015). Free vibration analysis of cylindrical orthotropic circular plates. Journal of Harbin Engineering University 36(7): 981-986. https://doi.org/10.3969/j.issn.1006-7043.201404082
 Ye CM, Wu WQ. (1997). Numerical simulation of vortex movement for the flow past a circular cylinder and the analysis of wake instability. Journal of Engineering Thermophysics 18(2): 169-172.
 Ling GC, Yin XY. (1982). Secondary vortex and the process of the formation of karman vortex. Chinese Journal of Theoretical and Applied Mechanics 18(1): 18-25, 111-112.
 Gerrard JH. (1966). The mechanics of the formation region of vortices behind bluff bodies. Journal of Fluid Mechanics 25(2): 401-413. https://doi.org/10.1017/S0022112066001721
 Yoon J, Kim J, Choi H. (1996). Control of laminar vortex shedding behind a circular cylinder using tabs. Physics of Fluids, 8(2): 479-486. https://doi.org/10.1007/s12206-014-0317-x
 He C, Duan ZQ. (2012). Numerical simulation of two-dimensional laminar flow around circular cylinder with splitter plate. Journal of Southwest Jiaotong University 47(5): 826-830. https://doi.org/10.3969/j.issn.0258-2724.2012.05.015
 Hughes TJR, Franca P, Hulbert GM. (1989). A new finite element formulation for computational fluid dynamics: VIII. The galerkin/least-squares method for advective diffusive equations. Computer Methods in Applied Mechanics and Engineering 73(2): 173-189. https://doi.org/10.1016/0045-7825(89)90111-4
 Tan L, Zhu BS, Wang YC, et al. (2014). Turbulent flow simulation using large eddy simulation combined with characteristic-based split scheme. Computers& Fluids 94(1): 161-172. https://doi.org/10.1016/j.compfluid.2014.01.037
 Wang DG, Wang HJ, Xiong JH, Tham LG. (2011). Characteristic-based operator-splitting finite element method for navier-stokes equations. Science China Technological Sciences 54(8): 2157-2166. https://doi.org/10.1007/s11431-011-4444-7
 Glowinski R, Pironneau O. (1992). Finite element method for the Navier-Stokes equations. Annual Review of Fluid Mechanics 24(1): 167-204.
 Shui QX, Wang DG, Wang W. (2016). Numerical Simulation of the characteristics of flow past circular cylinder with splitter plate. Advances in Water Science 27(4): 586-592. https://doi.org/10.14042/j.cnki.32.1309.2016.04.013
 Ding H, Shu C, Yeo K S, Xu D. (2007). Numerical simulation of flows around two circular cylinders by mesh-free least square-based finite difference methods. International Journal for Numerical Methods in Fluids 53(2): 305-332. https://doi.org/10.1002/fld.1281
 Harichandan AB, Roy A. (2010). Numerical investigation of low Reynolds number flow past two and three circular cylinders using unstructured grid CFR scheme. International Journal of Heat and Fluid Flow 31(2): 154-171. https://doi.org/10.1016/j.ijheatfluidflow.2010.01.007
 He C, Duan ZQ. (2012). Numerical simulation of two-dimensional laminar flow around circular cylinder with splitter plate. Journal of Southwest Jiaotong University 47(5): 826-831. https://doi.org/10.3969/j.issn.0258-2724.2012.05.015