  The kinematics of a gliding flat-plate with spanwise oscillation has been
optimized to enhance the power efficiency by using Bayesian optimization
method, in which the portfolio allocation framework consists of a Gaussian
process probabilistic surrogate and a hybrid acquisition strategy. We tune
three types of acquisition function in the optimization framework and assign
three different balance parameters to each acquisition function. The design
variables are set as the dimensionless oscillating amplitude and reduced
frequency of the spanwise oscillation. The object function is to maximize the
power factor to support a unit weight. The optimization results in a maximal
power factor of 1.65 when the dimensionless oscillating amplitude and reduced
frequency vary from 0 to 1. The features of the probabilistic response surface
are also examined. There exists an optimal reduced frequency for the power
efficiency at the oscillating amplitudes above 0.40. In addition, the higher
power efficiency may be obtained by increasing the amplitude beyond 1.00.
