The model examines the unsteady, incompressible flow past a long cylinder placed in a fluid flow channel at right angle. Vortex is triggered in the system by an offset cylindrical geometry placed in the channel. In this case, an unstructured mesh with asymmetry was used to trigger vortex at the lowest computation time. The flow is a fully developed, steady and non-turbulent in nature (Re = 100). The repeating von Kármán vortex street behind a bluff body caused by Vortex shedding - responsible for unsteady separation of fluid flow is studied in this work using COMSOL Multiphysics Non-Linear solver for Single-Phase Laminar Flow.
Baseline CAD Model
The rectangle depicts the fluid flow domain and the hole depicts the CS of the cylindrical obstruction.
In the Pressure profile plot, the vortex pattern can be observed behind the cylindrical body as a result of strong separation and pressure gradient due to asymmetry in the positioning of the obstruction.
An Unstructured Triangular Element Free Mesh with Very Fine Grain Size is created. Unstructured mesh reduces computation time and moreover, the critical region in the domain is very small which is captured by a structured boundary Washer Layers around it.
The dimensionless Lift vs. time shows the unsteady nature of the flow and Vortecity behind the bluff body.
The dimensionless drag vs. time shows the drag force behind the object with time.
Simulation of the Velocity Profile of the Fluid.
The pattern resulting from the geometry traces the von Kármán path. The path is traced by drag driven particle motion and line pathways.