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The paper presents a novel extension of the two-dimensional Vortex Particle Method which allows complex transient flow features computed by an original simulation to be recreated for use as inflow conditions in other simulations. This is facilitated by recording velocity time signals of the original simulation and computing time traces of vortex particles to be seeded into the secondary simulation near its upstream domain boundary. The proposed Flow Reproduction Method (FRM) thus allows us to re-create the flow field, without the need to simulate the underlying physics responsible for the flow features. A natural field of application is the re-creation of wakes from flows past bluff bodies of arbitrarily complex geometry, the resolution of which is computationally expensive. The recording is performed on a sampling system of the velocity field. Reproduction of the sampled simulation is then performed by inserting vortex particles in defined positions and time intervals into the secondary simulation. This proceeds in a smaller domain with the advantage of significantly reduced computational cost. In the simulations presented here, wake flows of upstream cylinders are reproduced. Convergence studies are performed to validate the FRM. The quality of flow reproduction is assessed and quantified. The computational efficiency of the reproduction simulation is enhanced additionally by using different adaptive numerical techniques. The method is then applied to fluid-structure interaction simulations of a wake buffeting problem. Good agreement is found between the dynamic response quantities when comparing original simulations and those with reproduced flows, whereby the latter are performed up to five times faster. [ABSTRACT FROM AUTHOR]

This paper aims to provide a comprehensive review of the literature and to impart a perspective on the current status and future directions for fundamentals of flow around and heat transfer from a square cylinder with modified corners. The focus is on how rounded, chamfered, recessed, and cut corners of a square cylinder impact the wake structure, flow instability, fluid forces, vortex dynamics, wake width, vortex formation length, boundary layer thickness, displacement thickness, transition to turbulence, drag crisis, and heat transfer. A circular cylinder undergoes drag crisis flow while a square cylinder does not. Sufficiently rounded corners can rejuvenate the drag crisis flow. The corner modifications encompassing heat transfer performance from low to high can be sorted out as sharp, cut, rounded, and chamfered, given the same scale of modifications. Based on the review and analysis of data in the literature, the optimal corner modifications are suggested for reduced forces and enhanced heat transfer. The research gap in the literature is identified and put forward for future investigations. [Display omitted] • Flow around and heat transfer from a square cylinder with modified corners are reviewed. • Focus is on how rounded, chamfered, recessed, and cut corners impact the wake structure. • Flow instability, fluid forces, transition, drag crisis, and heat transfer are summarized. • No drag crisis flow for square cylinder, but sufficiently rounded corners can rejuvenate it. • Optimal corner modifications are suggested for reduced forces and enhanced heat transfer. [ABSTRACT FROM AUTHOR]

Detached Eddy Simulation (DES) has been used to investigate the effect of the Reynolds number on the wake of a high-speed train in the range from 5.2 ​× ​105 to 2.2 ​× ​107. Then, the characteristics of vortex structure, streamlines distribution, velocity characteristics, and pressure characteristics in the wake region of the high-speed train at five Reynolds numbers are studied. The results show that with the increase of the Reynolds number, some small-scale vortices emerge in the wake region of the high-speed train, which increases the complexity of the wake vortex structure, but the large-scale vortex structure has not changed significantly. The separation lines and vortices distributed on the train surface, and the characteristics of the pressure distribution in the wake region do not change considerably at different Reynolds numbers. The frequency of the vortex shedding from the train based on Strouhal number is approximately a constant at five Reynolds numbers, and the phenomenon and mechanism of the flow in the wake region are almost the same within the range of Reynolds number selected in this study. With the increase of the Reynolds number, the fluctuation degree of the velocity and pressure, and the vorticity in the wake region increase substantially. • DES has been used to investigate the wake characteristics of a high-speed train at five Reynolds numbers. • With the increase of Re , small-scale vortices emerge, but the large-scale vortex structure has not changed significantly. • The separation lines and vortices distributed on the train surface do not change considerably at different Re. • The phenomenon and mechanism of the flow in wake region is almost same within the range of Re from 5.2 × 105 to 2.2 × 107. • With the increase of Re , the fluctuation degree of velocity and pressure, and the vorticity in the wake region increase. [ABSTRACT FROM AUTHOR]