GPU-Accelerated High-Fidelity Implicit Large Eddy Simulations of Coandă Cylinder Flow Instabilities

The Coandă effect has various practical applications in aerodynamic design, such as active flow control around airfoils and rotor blades, lift generation (e.g., no-tail-rotor helicopters) and wind-energy harvesters. This work entails the numerical study of steady and unsteady flow control of a Coandă cylinder in a freestream, with the objective of understanding the mechanisms affecting the lift generation around it. Numerical studies were performed using the open source solver PyFR (www.pyfr.org), which is a high-order Implicit Large Eddy Simulation (ILES) solver based on Flux Reconstruction (FR) discretization of the compressible Navier-Stokes equations. Simulations were performed for momentum coefficients ranging from 0.04 to 0.08 with an inflow Reynolds number of 20,000 for the cases of steady and alternating slot blowing. A comparison of two different cylinder slot configurations (single slot and double slot) was also made. CFD results were compared to experimental data and were qualitatively similar. A noticeable increase in lift was observed at higher momentum coefficients and the double slot configuration generated greater lift compared to its single slot counterpart for the same momentum coefficient. The differences between computation and experiments were attributed to the relatively large spanwise grid spacing.