A seal assembly between a disc cavity and a turbine section hot gas path includes a stationary vane assembly and 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 includes a radially outwardly facing first surface, a radially inwardly facing second surface, a third surface, and a plurality of grooves extending into the third surface. The grooves are arranged such that a space is defined between adjacent grooves. 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.