“…The high fidelity solver is only used to generate the snapshots and the training dataset, guaranteeing a complete decoupling between the online evaluation and the offline training. There is a lot of work on the non-intrusive method in the past, such as the regression-based non-intrusive RB methods including the tensor decomposition based regression (see, e.g., for parametrized time-dependent problem [2]), the artificial neural networks (ANNs) based regression (see, e.g., for steady-state problem [34], for combustion problem [18], and for transient flow [35]), and the Gaussian processes regression (GPR) based regression (see, e.g., for nonlinear structural analysis [36], and for compressible flow [31]), and the interpolation-based non-intrusive RB methods comprising the radial basis function (RBF) interpolations (see, e.g., for parametrized time-dependent PDE [37], for multiphase flows in porous media [38], and for shallow water equations [39]), the polynomial interpolations (see, e.g., for parametrized timedependent problems [40], for stochastic representations in UQ analysis [41]), and the cubic spline interpolations (CSI) (see, e.g., for parametric applications in transonic aerodynamics [42], and for non-linear parametrized physical problems [43]).…”