The hard drive industry widely views heat assisted magnetic recording (HAMR) as the technology to achieve 4 Tb/in 2 and greater storage densities and recapture the aggressive storage density growth rates of years past so that hard disk drives are able to meet the world's exploding data storage demand. While traditional magnetic media is thermally unstable at room temperature for the small bit sizes needed for high density recording, the high coercivity HAMR magnetic media can safely store digital data at very small bit sizes of (25 nm) 2. In order to write data, a near-field optical system confines electromagnetic energy below the dffraction limit to locally heat the HAMR recording bit to 400-500 C within a few nanoseconds. This adds new thermal complications to the already difficult mechanical and tribological design challenges for the head-disk interface (HDI) region. The reliability of hard drive read-write performance depends on the ability of the recording head slider, which contains the read and write elements, to stably fly in close proximity (< 5 nm) to the spinning recording disk. HAMR technology introduces heat-dissipating components and rapid thermal uctuations to the HDI system not seen in traditional hard drives. Numerical simulations provide insightful information into the performance of HDI components that are difficult or impossible to attain experimentally.