In CFD simulations, determining the appropriate inlet and outlet boundary conditions is crucial for accurately modeling recirculation phenomena in both two-dimensional (2D) and three-dimensional (3D) scenarios.

For recirculation simulations, the inlet boundary condition typically involves prescribing the flow properties entering the domain. This may include specifying the velocity profile, temperature, turbulence characteristics, and any other relevant parameters. In 2D simulations, the inlet boundary condition can be defined as a 2D plane through which fluid enters the computational domain. In 3D simulations, this boundary condition extends to a full 3D volume or surface. In both 2D and 3D simulations, accurately representing the inlet and outlet boundary conditions is critical for capturing the complex flow dynamics associated with recirculation zones. Properly defined boundary conditions ensure that the simulated flow field closely matches the real-world behavior, thus enhancing the reliability and accuracy of the CFD predictions.