Analysis of outflow boundary condition implementations for 1D blood flow models

We performed a thorough evaluation of three main implementation types for outflow boundary conditions of one-dimensional blood flow models: the implicit Lax-Wendroff implementation, the explicit Lax-Wendroff implementation and the implicit method of characteristics implementation. The three implementation types have been applied for resistance and Windkessel outflow boundary conditions. The results show that the implicit Lax-Wendroff method leads to the greatest execution times and can not be used for medium and small vessels due to its divergent behavior. The explicit Lax-Wendroff method offers the best compromise between accuracy and execution speed. The implicit method of characteristics should only be used when the explicit Lax-Wendroff method diverges.