Numerical study on near wake flows of a flat plate in three lands of oncoming flow is made using discrete vortex model and some improved techniques. For steady oncoming flow, the gross and detailed features are calculated and discussed. For harmonic oscillatory oncoming flow the different wake flow patterns are obtained for KC=2, 4 and 10. Our results for low KC numbers present a new wake flow pattern describing a new mode of vortex shedding, pairing and moving. The calculated drag and inertia force coefficients are closer to experimental data from U- tube than the previous results of vortex simulation. For in- line combined oncoming flow the vortex lock- In and dynamic characteristics are Simulated and compare well with experiments.
The discrete vortex simulation of flow over a plate in Uniform oncoming flow has been well studied and reviewed by many Investigators. In the simulation the vorticity creation technique has been a major concern which has been provided by MVP (Sarpkaya, 1975), MFP (Klya et ai, 1977), and other approach (Chein et ai, 1988). The gross features of the flow field such as the vortex shedding frequency, the drag coefficients and the vorticity shedding rate predicted in their studies are In fair agreement with experimental measurements. The discrete vortex calculations of the detailed features of the near wake, such as the velocity profiles, the turbulent intensities and Reynolds stress were also performed by Klya et al (1982) and Chein et al (1988), and some predictions are compared With experimental data. Concerning the near wake flows of a flat plate In unsteady oncoming flows, Graham (1979,1985) and other investigators have applied different vortex models to study the near wake flow of the plate in harmonic oscillatory flows.