This nozzle impinges the fluid upon a protruding spiral. Prolonged immobilization facilitates tissue proliferation which impinges on the joint space. An incident, spatially extended beam (mostly of X-rays, or neutrons) impinges on a sample. An edge tone occurs when a jet impinges on a fixed surface. The jet impinges on a sharp ended ring with two toroidal cavities on either side. When the arsenic vapor impinges on a cold surface, a mirror-like deposit of arsenic forms. A plane wave impinges on a site, and a spherical wave exits it. The protrusio may progress until the femoral neck impinges against the pelvis. The previous analyses assumes the flow impinges in normal direction. A ramp on the slide impinges on the lower pin.