*3.3. Solving Method*

The turbulence, pressure, momentum, and other fluid control equations used the second-order upwind spatial discretization algorithm, and the gradient calculation used an algorithm based on a least squares unit [32]. The discretization was performed using the second-order upwind difference scheme, and the transient term was discretized using the second-order backward Euler scheme. The first-order algorithm was used for preliminary calculation and then the second-order algorithm was used to improve the calculation accuracy. All simulation conditions adopted the pressure-velocity (SIMPLEC) coupling method, and the convergence was determined by the size of the residual error of the governing equation [33]. The continuity equation, momentum equation, k equation, and ω of all scale residuals below 1 × <sup>10</sup>−<sup>5</sup> were used. The equation was used as the convergence criterion, and the corresponding calculation results were observed to be stable, which can be considered reliable results.
