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In this work, the authors utilize a lattice-Boltzmann lattice-spring method to simulate the deformation of blockages and fluid properties in an elastic blood vessel for the first time. Precisely, in this method, the lattice Boltzmann method is used to capture fluid behavior, and the lattice spring model is employed to mimic the deformation of the blood vessel and blockages while the immersed boundary method is applied to deal with the fluid-solid interaction. A validation of the present method is carried out by comparing the simulation results with a theoretical prediction of deformation of a pulmonary blood vessel in a steady flow. Subsequently, the method is applied to study the relationship between the fluid properties and the deformation of blockages. It is found that the blockages are rotated and expanded to the vessel central area so that a narrow gap or opening is formed in the blood vessel. The opening and flow rates decrease and the pressure drop increases as the thickness and deformation of the blockages increase. [ABSTRACT FROM AUTHOR]

Dynamic motion of two flexible fibers settling in an infinitely long fluid column at moderate Reynolds numbers is numerically simulated in a three-dimensional space by using a lattice-Boltzmann lattice-spring method. In the simulations, rectangular and cylindrical flexible fibers are used. The fiber rigidity, density, shape, initial distance, and aspect ratio are varied at different levels and their effects on drafting, kissing, and tumbling (DKT) behavior are studied. It is demonstrated that the fiber rigidity has a profound impact on settling velocity, fluid structures, and DKT phenomenon. [ABSTRACT FROM AUTHOR]