A seal assembly between a disc cavity and a hot gas path that extends through a turbine section of a gas turbine engine comprising: a stationary vane assembly including a plurality of vanes and an inner shroud; a rotating blade assembly downstream from the vane assembly and including a plurality of blades that are supported on a platform and rotate with a turbine rotor and the platform during operation of the engine, the platform comprising: a radially outwardly facing first surface; a radially inwardly facing second surface; a third surface facing an axial direction defined by a longitudinal axis of the turbine section; and a plurality of grooves extending into the third surface, the grooves being arranged such that a space having a component in a circumferential direction is defined between adjacent grooves, the circumferential direction corresponding to a direction of rotation of the blade assembly; wherein, during operation of the engine, the grooves guide purge air out of the disc cavity toward the hot gas path such that the purge air flows in a desired direction with reference to a direction of hot gas flow through the hot gas path, characterised in that the grooves are tapered from entrances thereof located distal from the first surface of the platform to exits thereof located proximate to the first surface of the platform such that the entrances are wider than the exits. a stationary vane assembly including a plurality of vanes and an inner shroud; a rotating blade assembly downstream from the vane assembly and including a plurality of blades that are supported on a platform and rotate with a turbine rotor and the platform during operation of the engine, the platform comprising: a radially outwardly facing first surface; a radially inwardly facing second surface; a third surface facing an axial direction defined by a longitudinal axis of the turbine section; and a plurality of grooves extending into the third surface, the grooves being arranged such that a space having a component in a circumferential direction is defined between adjacent grooves, the circumferential direction corresponding to a direction of rotation of the blade assembly; wherein, during operation of the engine, the grooves guide purge air out of the disc cavity toward the hot gas path such that the purge air flows in a desired direction with reference to a direction of hot gas flow through the hot gas path, characterised in that the grooves are tapered from entrances thereof located distal from the first surface of the platform to exits thereof located proximate to the first surface of the platform such that the entrances are wider than the exits. a radially outwardly facing first surface; a radially inwardly facing second surface; a third surface facing an axial direction defined by a longitudinal axis of the turbine section; and a plurality of grooves extending into the third surface, the grooves being arranged such that a space having a component in a circumferential direction is defined between adjacent grooves, the circumferential direction corresponding to a direction of rotation of the blade assembly; wherein, during operation of the engine, the grooves guide purge air out of the disc cavity toward the hot gas path such that the purge air flows in a desired direction with reference to a direction of hot gas flow through the hot gas path, characterised in that the grooves are tapered from entrances thereof located distal from the first surface of the platform to exits thereof located proximate to the first surface of the platform such that the entrances are wider than the exits.