Fully discrete finite element approximation for the projection method to solve the chemotaxis-fluid system

In this paper, we investigate a chemotaxis-fluid interaction model governed by the incompressible Navier-Stokes equations coupled with the classical Keller-Segel chemotaxis system. To numerically solve this coupled system, we develop a pressure-correction finite element method based on a projection method. The proposed scheme employs a backward Euler method for temporal discretization and a mixed finite element method for spatial discretization. Nonlinear terms are treated semi-implicitly to enhance computational stability and efficiency. We further establish a rigorous error estimates for the fully discrete scheme under the time step condition τ ≤ Ch , demonstrating the convergence of the numerical method. A series of numerical experiments are conducted to validate the stability, accuracy, and effectiveness of the proposed method. The results confirm the scheme’s capability to capture the essential dynamical behaviors and characteristic features of the chemotaxis-fluid system.