A data center rack assembly includes a rack, an electronic device, and an adjustable air duct. The rack includes a frame defining opposite first and second rack sides spaced apart in a longitudinal direction. The electronic device presents an intake side configured to receive air therethrough for passage into the electronic device. The electronic device is mounted to the frame such that the intake side is disposed intermediately between the rack sides and is spaced from the first rack side to define a longitudinal dimension therebetween. The duct includes relatively shiftable first and second duct sections that extend in the longitudinal direction to cooperatively present an adjustable longitudinal duct length, and a drive mechanism operably coupled to the first and second sections to control relative shifting of the sections in the longitudinal direction to thereby adjust the longitudinal duct length to correspond with the longitudinal dimension.