Accession Number:

ADA551578

Title:

Resistance in Unsteady Flow - Search for a Model

Descriptive Note:

Annual rept.

Corporate Author:

NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF MECHANICAL ENGINEERING

Personal Author(s):

Report Date:

1998-01-01

Pagination or Media Count:

6.0

Abstract:

To devise a physics-based model through the use of analytical, numerical, physical, and thought experiments for the prediction of flow-induced unsteady forces on bluff bodies immersed in time dependent flows. The new model is expected to replace the Morison equation hereafter called the MOJS equation and offer greater universality, particularly in the inertiadrag regime, in calculating forces and dynamic response of cylinders in sinusoidal and non-sinusoidal flows. The initial objectives of this research were 1 To examine the merits and shortcoming of the existing unsteady-flow force-prediction models, and 2 To assess the assertion that the viscous drag force and the inviscid inertia force operate independently and therefore it is possible to divide the measured time dependent force into two distinct components an inviscid inertial force and a viscous drag force Lighthill, 1986. Extensive calculations have proved Lighthills proposal to be incorrect. Instead, the objective of the investigation became the development of a three-term MOJS equation A velocity-square- dependent drag, an acceleration-dependent inertial force, and a second-order correction to the inertial force, without introducing any new empirical coefficients. This objective has been achieved.

Subject Categories:

  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE