Numerical Simulation of Viscoelastic Fluid around Oscillating Cylinder

Vortex shedding is a common phenomena when a fluid flow passes  around a body. Here, the vortex shedding of viscoelastic fluid around oscillating cylinder is simulated.  For simulation, dynamic mesh library is added to OpenFOAM solver viscoelasticFluidFlow. The solver is available only in foam-extended versions.

vortex shedding in oscillating cylinder using extending viscoelasticFluidFoam
vortex shedding in oscillating cylinder via extending viscoelasticFluidFlow

DynamicMesh settings in OpenFOAM

In dynamicMesh library, there are different methods to handle grid after cylinder displacement. I used displacementLaplacian in this simulation which solve a Laplace equation to relocate  cell’s vertices  in grid.


where diffusivity and C are the diffusivity coefficient and the position of vertices, respectively. There are several ways to assign diffusivity, here inversePointDistance is chosen where diffusivity value has inverse relation with distance to the patch

diffusivity  inversePointDistance 1(cylinder);

The cylinder displacement is considered via the oscillatingDisplacement boundary condition. This BC needs two entries: oscillating velocity (omega) and amplitude.

grid motion in oscillating cylinder problem
grid motion in oscillating cylinder problem

Drag and lift force calculation

Also, the forces library is modified to compute  lift and drag on viscoelastic fluid flow. The implemented code for forces is available here. The lift and drag coefficient is shown in below.

Drag and lift on oscillating cylinder
Drag and lift on oscillating cylinder