  This paper proposes a scalable lattice-Boltzmann computational framework
(SBoTFlow) for simulations of flexible moving objects in an incompressible
fluid flow. Behavior of fluid flow formed from moving boundaries of
flexible-object motions is obtained through the multidirect forcing immersed
boundary scheme associated with the lattice Boltzmann equation with a parallel
topology-confined block refinement framework. We first demonstrate that the
hydrodynamic quantities computed in this manner for standard benchmarks,
including the Tayler-Green vortex flow and flow over an obstacle-embedded
lid-driven cavity and an isolated circular cylinder, agree well with those
previously published in the literature. We then exploit the framework to probe
the underlying dynamic properties contributing to fluid flow under flexible
motions at different Reynolds numbers by simulating large-scale flapping wing
motions of both amplitude and frequency. The analysis shows that the proposed
numerical framework for pitching and flapping motions has a strong ability to
accurately capture high amplitudes, specifically up to $64^\circ$, and a
frequency of $f=1/2.5\pi$. This suggests that the present parallel numerical
framework has the potential to be used in studying flexible motions, such as
insect flight or wing aerodynamics.
