An assembly includes a housing having a housing cavity, an inlet, and an outlet, a rotatable shaft positioned proximate the outlet, and a seal positioned at an interface of the rotatable shaft and the housing. The seal includes porous material adjacent the shaft and the housing and a shell substantially separating the porous material from the housing cavity. The shell includes an inlet that allows fluid flow from the housing cavity to the porous material and an outlet that allows fluid flow from the porous material to the housing interior. The inlet is positioned radially inward of the outlet.