Direct Computation of a Hole-Tone Feedback System at Very Low Mach Numbers

Computation of Airfoils at Very Low Reynolds Numbers

We discuss a new numerical scheme involving adaptive boundary conditions which allows to compute, at very low Reynolds numbers, drag and lift of airfoils with rough surfaces efficiently with great precision. As an example we present the numerical implementation for an airfoil consisting of a line segment. The solution of the NavierStokes equations is singular at the leading and the trailing edg...

A preconditioned solver for sharp resolution of multiphase flows at all Mach numbers

A preconditioned five-equation two-phase model coupled with an interface sharpening technique is introduced for simulation of a wide range of multiphase flows with both high and low Mach regimes. Harten-Lax-van Leer-Contact (HLLC) Riemann solver is implemented for solving the discretized equations while tangent of hyperbola for interface capturing (THINC) interface sharpening method is applied ...

Suboptimal feedback control of vortex shedding at low Reynolds numbers

The objective of this study is to develop a method of controlling vortex shedding behind a bluff body using control theory. A suboptimal feedback control procedure for local sensing and local actuation is developed and applied to the flow behind a circular cylinder. The location of sensors for feedback is limited to the cylinder surface and the control input from actuators is the blowing and su...

Direct Numerical Aeroacoustics for Low Mach Numbers Using One Unstructured Grid

Using an unstructured grid, for which the mesh size is adapted to the local flow and acoustic solution, one can reduce the number of unknowns needed for a direct aeroacoustic simulation. The compressible Navier-Stokes equations for Mach numbers 0 < M < 1 are considered. However, the unstructured grid together with the increasing stiffness of the problem for M → 0 reveals new numerical challenge...

Entropy Splitting for High Order Numerical Simulation of Vortex Sound at Low Mach Numbers