The dynamic mesh technique and User-Defined Function (UDF) are used to simulate the cylinder motion. A transversely oscillating circular cylinder in combination of uniform flow and oscillating flow at low Reynolds number is simulated. The uniform flow and oscillating flow both are x direction. SIMPLE algorithm is used to solve the Navier- Stokes equations. In this paper, we compute the lift and drag coefficient changing with time and draw the map of vorticity isolines at phase angleφ = 3π / 2. Force time histories are shown for uniform flow at Reynolds number (Re) of 200 and for the combination of uniform and oscillating flow.
In recent years, increasingly more and more exploration and production have shifted to deeper waters. Marine risers remain to be technically challenging in deep sea. More and more pivotal components of the circular cylinder shape represented by marine risers are widely used in the offshore platform and subsea pipeline systems. Many works focus on the research of circular cylinder in uniform flow and oscillating flow. Gu et al. (1994) found that vortex from one side of the cylinder to the other reach to a high degree of concentration of vorticity next to cylinder when the s f / f increased (f is the oscillating frequency of cylinder, s f is he shedding frequency for the fixed cylinder). Lu and Dalton (1996) studied the vortex shedding from a transversely oscillating circular cylinder in a uniform flow by numerical solutions. The impact of increasing the amplitude of oscillating cylinder and Reynolds number are shown to lower the value of s f / f at which vortex switching. Wang and Zhou (2005) studied a circular cylinder oscillating transversely in a uniform flow and verified the conclusion of Lu & Dalton.