Masayuki Kaiho

Decreasing Airflow Velocity in Hard Disk Drives With a Spoiler and Bypass

High-speed disk rotation of hard disk drives (HDDs) produces high-speed airflow, which causes disk vibration called disk flutter, and vibration of the head carriage arm. These vibrations have a significant effect on the positioning precision of the head and should be reduced by considering aerodynamic factors. The airflow changes in HDD with a bypass and a spoiler were clarified by LES and PIV . These analyses show that a spoiler reduces the arm vibration by decreasing the flow velocity near the arm, in particular, decreasing the average flow velocity between the disks, diversing the flow into the bypass channel, and moving the high-speed-flow area toward the inner radius area of the disks.

PARALLEL OVERLAPPING SCHEME FOR VISCOUS INCOMPRESSIBLE FLOWS

SUMMARY A 3D parallel overlapping scheme for viscous incompressible flow problems is presented that combines the finite element method, which is best suited for analysing flow in any arbitrarily shaped flow geometry, with the finite difference method, which is advantageous in terms of both computing time and computer storage. A modified ABMAC method is used as the solution algorithm, to which a sophisticated time integration scheme proposed by the present authors has been applied. Parallelization is based on the domain decomposition method. The RGB (recursive graph bisection) algorithm is used for the decomposition of the FEM mesh and simple slice decomposition is used for the FDM mesh. Some estimates of the parallel performance of FEM, FDM and overlapping computations are presented. 1997 by John Wiley & Sons, Ltd.

FEM/FDM composite scheme for viscous incompressible flow analysis

Abstract A new FEM/FDM composite scheme for incompressible flow problems is presented combining the finite element method, which is best suited to analyze flow in any arbitrarily shaped flow geometry, with the finite difference method, which is advantageous in both computing time and computer storage. The combination of both methods enables large-scale viscous flow to be analyzed, which is crucial for both the detailed analysis of three-dimensional flows and the solving of flow problems around moving bodies. A modified ABMAC method is used as the basic algorithm, to which a sophisticated time integration scheme has been applied. Numerical results including moving boundary problems and three-dimensional problems indicate good agreement with experimental results.

Investigation of Airflow Velocity Distribution in Hard Disk Drives Using LES and PIV

This paper deals with the specific tools necessary to investigate airflow in HDD with the aerodynamic parts. The simulation modeling of HDD is made by using large eddy simulation (LES), which covers most of the configuration between the two co-rotating disks, including the arm assembly and effective methods for investigating the airflow inside an actual HDD, namely, particle image velocimetry (PIV) with tetrahedral elements.

5728 Decreasing Airflow Velocity in Hard Disk Drives with a Spoiler and Bypass

Airflow changes in a hard disk drive (HDD) with a bypass and a spoiler were clarified by large eddy simulation (LES) and particle image velocimetry (PIV). These analyses show that the spoiler decreases the flow velocity near the arm by decreasing average flow velocity between the disks such as diverging the flow into the bypass channel, and by moving the high-speed-flow area toward the inner-radius area of the disks. The arm vibration is reduced with 30% by these effects

Application of a 3-D FEM/FDM Overlapping Scheme to Heat and Mass Transfer and Moving-Boundary Problems

A 3-D FEM/FDM overlapping scheme for viscous, incompressible flow problems is presented that combines the finite element method, which is best suited to analyze flow in any arbitrarily shaped flow geometry, with the finite difference method, which is advantageous in both computing time and computer storage. The combination of both methods enables large-scale viscous flow to be analyzed, which is crucial both for detailed analysis of 3-D flows and for solving flow problems around moving bodies, A modified ABM AC method is used as the basic algorithm, to which a sophisticated time integration scheme, proposed by the present authors, has been applied. In this paper, some numerical results including 3-D heat and mass transfer problem and moving-boundary problems are presented.

Airflow Simulation around Railroad Cars of Shin-Kan-Sen

A new FEM/FDM composite scheme for two-dimensional incompressible flow problems combining the finite element method which is best suited to analyse flow in any arbitrarily shaped flow geometry and the finite difference method which is advantageous in both computing time and computer storage is presented. The combination of both methods enables large-scale viscous flows to be analysed and it is crucial for both the detailed analysis of three-dimensional flows and the solving of flow problems around moving bodies. Numerical results for cars of a railroad car entering a tunnel and cars passing each other correlate well with results obtained by measurements on actual cars and model analysis.