Cylinder/Channel inject from the left and use no-slip top/bottom walls. Cavity has a moving lid at the top with no-slip walls on the other three sides.

Inlet u in lattice units / 100; viscosity nu in lattice units / 1000. Lower viscosity (smaller nu) gives higher Reynolds number and more turbulent shedding.

Drag the obstacle to move it. Scroll over the canvas to rotate. The yellow arrow shows instantaneous force on the obstacle.