A flow device for an additive manufacturing device for the production of a three-dimensional object by layer-wise selective solidification of a building material in a build area , the flow device comprising: a process chamber , a gas supply device for generating a gas stream in the additive manufacturing device , at least one gas inlet for introducing the gas stream into the process chamber and at least one gas outlet for directing the gas stream out of the process chamber , and a gas supply line , which is provided outside the process chamber , in order to conduct gas to the at least one gas inlet , the gas supply line comprising at least a first line section which adjoins the gas inlet and which extends a length (L) along a first extension direction of the gas supply line , the first extension direction being substantially straight, and wherein the first line section extends a maximum value of a width (B) that extends transverse to the first extension direction and parallel to the build area , and wherein the length (L) of the first line section is at least as large as one half of the maximum value of the width (B) and wherein the first line section further comprises a first subsection that is arranged at a distance from the gas inlet and which comprises at least a first flow conditioning unit in addition to a wall of the first line section , the first flow conditioning unit being designed to substantially align the gas stream in the first extension direction, characterized in that the gas supply line comprises at least a second line section which adjoins the first subsection of the first line section and which extends along a second extension direction of the gas supply line that differs from the first extension direction, and wherein the first flow conditioning unit of the first line section extends into the second line section . a process chamber , a gas supply device for generating a gas stream in the additive manufacturing device , at least one gas inlet for introducing the gas stream into the process chamber and at least one gas outlet for directing the gas stream out of the process chamber , and a gas supply line , which is provided outside the process chamber , in order to conduct gas to the at least one gas inlet , the gas supply line comprising at least a first line section which adjoins the gas inlet and which extends a length (L) along a first extension direction of the gas supply line , the first extension direction being substantially straight, and wherein the first line section extends a maximum value of a width (B) that extends transverse to the first extension direction and parallel to the build area , and wherein the length (L) of the first line section is at least as large as one half of the maximum value of the width (B) and wherein the first line section further comprises a first subsection that is arranged at a distance from the gas inlet and which comprises at least a first flow conditioning unit in addition to a wall of the first line section , the first flow conditioning unit being designed to substantially align the gas stream in the first extension direction, characterized in that the gas supply line comprises at least a second line section which adjoins the first subsection of the first line section and which extends along a second extension direction of the gas supply line that differs from the first extension direction, and wherein the first flow conditioning unit of the first line section extends into the second line section . <EOS>