Numerical modeling of magnetic head positioning error due to flow-suspension interactions in disk drives

Flow-induced vibrations arise in many engineering applications. This class of problems is commonly tackled by investigating the flow field around the obstruction as well as the influence of the aerodynamic excitations on the oscillations of the obstruction. The problem of flow-suspension interactions in computer hard disk drives (HDDs) is studied numerically in the present investigation. It is assumed that the calculations of the flow are not affected by the suspension oscillations whereas the suspension is fully exposed to the aerodynamic excitations.; The flow field around a pair of suspension-slider units (SSUs) is investigated for different cases. The vibration of the SSU is also analyzed using the aerodynamic excitations evaluated in the flow field analysis. The problem is tackled using both two- and three-dimensional models for the flow field and vibration analyses. The 2D models are developed by employing some physically motivated assumptions that (a) significantly reduce the complexity of the problem; and, (b) appear to be promising in capturing the essential physics of the problem.; The 2D flow field analysis is employed to determine the flow structures and the aerodynamic excitations at different sections along the suspension length. In addition, the 2D vibration analysis is conducted to evaluate the response of the SSU to the aerodynamic excitations. Flow field and vibration analyses are also conducted by means of 3D models. The velocity data measured through the current experiment is used as the velocity boundary condition for performing the 3D flow field calculations. Comparison of the 2D results with the 3D results reveals that: (a) the 2D flow model fails to capture all the important phenomena of the 3D flow past a pair of suspensions; and, (b) the 2D vibration analysis successfully mimics the dynamic characteristics of simple suspensions with sufficient accuracy. The effect of having a hole at the suspension base is also investigated using the 3D flow field and vibration analyses. In addition, the 3D calculations show that the slider significantly alters the flow pattern around a SSU, resulting in larger amplitudes of oscillations of the unit.