On the limits of added-mass theory in separated flows and with varying initial conditions

Journal article (2020)

Authors

J. N. Fernando Queen's University Belfast
Gabriel D. Weymouth Queen's University Belfast
David E. Rival Queen's University Belfast
Affiliation
External organisation
Vortex dynamics Swimming/flying Separated flows
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Published Date

2020

Language

English

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Abstract

It remains unclear to what extent inviscid added-mass theory accounts for the forces exerted on an accelerating body subjected to separated flow. In this study, reactant forces and velocity-field data are systematically acquired using experimental measurements and simulations of an accelerating circular flat plate. Cases accelerated from rest are compared to cases accelerated from a steady flow state. When the added-mass forces predicted by potential theory and the resistance forces associated with the instantaneous plate velocity are accounted for, the remaining (residual) forces comprise approximately 20% of the peak force, even at high accelerations. In addition, the computed residual forces during accelerations both from rest and steady-state cases yield good collapse with respect to one another, indicating that the total forces are not a strong function of the initial state of the wake. These results suggests that inviscid added-mass theory is inadequate to predict the full reactant force even in the ‘ideal’ condition of impulsive motion from rest.