UNSTEADY FORCES ON A BODY IMMERSED IN VISCOUS FLUIDS : 1ST REPORT: FOR A UNIFORMLY ACCELERATED ELLIPTIC CYLINDER

概要

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A new numerical method for obtaining the forces on a body immersed in viscous fluids is derived for a uniformly accelerated elliptic cylinder from rest. In an analytical study, Fourier series expansion and boundary layer variable expansion are used because of good convergence and accuracy at high Reynolds numbers. An application of discrete Fourier transform to a block tridiagonal matrix leads to a high speed calculation over ten times as fast as the SOR method. From this analysis, the coefficients of drag, lift and moment exerted on a unit spanlength are obtained, and they consist of two components due to pressure and viscous force. Distribution of vorticities on the surface, which is important for the characteristics of heat conduction, is reveal ed in detail. Furthermore, the authors confirm that the separation time shown by Blasius at the trailing edge has a larger error when the eccentricity of the elliptic cylinder goes to unity.
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