model Geometry = ClaRa.Basics.ControlVolumes.Fundamentals.Geometry.HollowCylinder(diameter = 4, length = 10, z_in = {0}, z_out = {10}, orientation = ClaRa.Basics.Choices.GeometryOrientation.vertical, flowOrientation = ClaRa.Basics.Choices.GeometryOrientation.vertical);