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

• Published in: Journal of fluids and structures 2020-02, Vol.93, p.102835, Article 102835
• Main Authors: Fernando, J.N., Weymouth, G.D., Rival, D.E.
• Format: Article
• Language: English
• Subjects: Separated flows; Swimming/flying; Vortex dynamics
• ISSN: 0889-9746; 1095-8622
• DOI: 10.1016/j.jfluidstructs.2019.102835

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.