We study the Casimir force in piston-like geometries semiclassically. The force on the piston is finite and physical, but to leading semiclassical approximation depends strongly on the shape of the surrounding cavity. Whereas this force is attractive for pistons in a parallelepiped with flat cylinder head, for which the semiclassical approximation by periodic orbits is exact, this approximation...

We extend the differential theory to anisotropic cylindrical structures with arbitrary cross-section. Two cases have to be distinguished. When the anisotropic cylinders do not contain the origin, the scattering matrix of the device is calculated from the extended differential theory with the help of the scattering matrix propagation algorithm. The fields outside the cylinders are described by F...

The direct numerical simulation (DNS) of unsteady flow past a square-cylinder has a very high computational cost, even at moderately low Reynolds-numbers (Re), where the transition to a complex 3D wake occurs. In fact, the cylinder wake is unstable to two main spanwise disturbances that are referred to as “Mode A” and “Mode B” in the literature, similarly to what happens for circular cylinders....