Parametric Study on the Velocity Sampling Techniques for the Actuator Line Method in 2D

摘要

The Actuator Line Method relies on tabulated 2D airfoil data in order to apply an equivalent force on the flowfleld. To find the appropriate force, the method samples the velocity in the flowfield to relate it to the freestream value needed by the 2D airfoil tables. Several velocity sampling techniques exist, but there is still no consensus on which one to choose for optimal performances. In order to eliminate possible 3D effects, this study compares the performances of the main sampling techniques in a 2D framework thus comparing them directly against the real freestream. The effects of parameters which might have an impact on the velocity sampling methods such as the type and resolution of the grid, type of solver, effects of the isometric Gaussian kernel and effects related to the airfoil profile are studied. The Integral Velocity Sampling outperforms the other methods due to its stability, flexibility, consistency and overall lower errors. Challenging flow conditions such as poor mesh resolution for a given Gaussian kernel width, high Drag and formation of a shock at high Mach still present a challenge.