Abstract-An interpolated velocity correction scheme for the simulation of the interaction between fluid and flexible boundary using an immersed boundary-lattice Boltzmann method (IB-LBM) is proposed. In the conventional IB-LBM, the velocity field on the immersed boundary is determined by interpolating from an Eluerian grid to a Lagrangian grid using a discrete Dirac delta function, which is not divergence-free. As a result, this method can generally suffer from poor volume conservation for the closed immersed boundary. The key idea of the proposed interpolated velocity correction scheme is correcting the interpolated velocity field to satisfy a discrete divergence-free constraint defined on the Lagrangian boundary in the fluid. The proposed scheme makes no modifications to solve Navier-Stokes (N-S) equations using the lattice Boltzmann method (LBM) on the Eulerian grid and also improves volume conservation for the closed immersed boundary. Two examples are presented to verify the efficiency and accuracy of the proposed scheme. proposed by Peskin [16] in 1970s for simulating cardiac mechanics and associated blood flow, which employs a fixed Eulerian grid for the flow field and a Lagrangian grid for an immersed boundary in the fluid, which is modeled by a singular force which is incorporated into the forcing term in the N-S equations. The interaction between the fluid and the immersed boundary is tackled using the IBM. A discrete Dirac delta function is used to spread the singular force from the Lagrangian grid to the Eluerian grid, and to interpolate the velocity from the Eluerian grid to the Lagrangian grid.It is well known that the IBM can suffer from poor volume conservation for the closed immersed boundary in the fluid [17]- [21]. One cause of this lack of volume conservation is that the interpolated velocity field that determines the motion of the Lagrangian structure is not generally divergence-free, even if the Eulerian velocity is divergence-free with respect to the discrete divergence operator used in the numerical solution of the incompressible N-S equations. This problem was solved by modifying their divergence operator relative to their chosen interpolation operator, which would remain discretely divergence free on the Lagrangian grid when interpolated with their specific interpolation operator [18]. The immersed interface method [19] modifies the finite difference stencils of the fluid solver near the immersed boundary instead of utilizing discrete delta functions to spread the force form the Lagrangian to Eulerian grid. The Blob projection method [20] finds an analytic expression that represents the projection of a regularized form of the forces along the boundary onto the space of divergence-free vector fields. However, all these methods are difficult to implement and are not readily extendable to three dimensions for general problems, they also need more computationally expensive interpolation and spreading. In our work, when the LBM is used for solving the N-S equations, the velocity field on th...