An airfoil of a turbine assembly, the airfoil having a pressure side and a suction side opposite the pressure side and extending between a leading edge of the airfoil and a trailing edge of the airfoil along an axial length of the airfoil, the airfoil including a cooling assembly comprising: a coolant chamber disposed inside the airfoil, the coolant chamber configured to direct coolant inside the airfoil; cooling channels (302, 304, 306) fluidly coupled with the coolant chamber, at least one (304, 306) of the cooling channels (302, 304, 306) configured to direct the coolant downstream in a direction (324, 326) from the leading edge toward the trailing edge of the airfoil, and at least one another of the cooling channels (302, 304, 306) configured to direct at least a portion of the coolant upstream in a direction away from the trailing edge toward the leading edge of the airfoil; and a trailing edge chamber connected with at least one of the cooling channels (302, 304, 306), the trailing edge chamber disposed at the trailing edge of the airfoil and including an inner surface, wherein the at least one of the cooling channels (302, 304, 306) is configured to direct at least a portion of the coolant in a direction toward the inner surface of the trailing edge chamber; a first cooling channel of the one or more cooling channels (304, 306) extending in a cross-sectional plane of the airfoil downstream in the direction (324, 326) from the leading edge toward the trailing edge and connected at one end to the coolant chamber and at the other end to the trailing edge chamber, the first cooling channel flanked in the cross-sectional plane toward the pressure side by a second cooling channel and toward the suction side by a third cooling channel, characterized in that: one of the second cooling channel and the third cooling channel extends from the coolant chamber in a downstream direction along one of the pressure side or the suction side, not reaching the trailing edge chamber, and the other of the second cooling channel and the third cooling channel having an inlet connected to the downstream end of the one of the second cooling channel and the third cooling channel and extending in an upstream direction along the other of the pressure side or the suction side. a coolant chamber disposed inside the airfoil, the coolant chamber configured to direct coolant inside the airfoil; cooling channels (302, 304, 306) fluidly coupled with the coolant chamber, at least one (304, 306) of the cooling channels (302, 304, 306) configured to direct the coolant downstream in a direction (324, 326) from the leading edge toward the trailing edge of the airfoil, and at least one another of the cooling channels (302, 304, 306) configured to direct at least a portion of the coolant upstream in a direction away from the trailing edge toward the leading edge of the airfoil; and a trailing edge chamber connected with at least one of the cooling channels (302, 304, 306), the trailing edge chamber disposed at the trailing edge of the airfoil and including an inner surface, wherein the at least one of the cooling channels (302, 304, 306) is configured to direct at least a portion of the coolant in a direction toward the inner surface of the trailing edge chamber; a first cooling channel of the one or more cooling channels (304, 306) extending in a cross-sectional plane of the airfoil downstream in the direction (324, 326) from the leading edge toward the trailing edge and connected at one end to the coolant chamber and at the other end to the trailing edge chamber, the first cooling channel flanked in the cross-sectional plane toward the pressure side by a second cooling channel and toward the suction side by a third cooling channel, characterized in that: one of the second cooling channel and the third cooling channel extends from the coolant chamber in a downstream direction along one of the pressure side or the suction side, not reaching the trailing edge chamber, and the other of the second cooling channel and the third cooling channel having an inlet connected to the downstream end of the one of the second cooling channel and the third cooling channel and extending in an upstream direction along the other of the pressure side or the suction side.