A higher-order grid is a technique that uses high-precision differencing or interpolation techniques to extend the values on the original low-resolution grid to a high-resolution grid. Generally speaking, the grid resolution directly affects the results of numerical simulation, and the higher the resolution, the higher the accuracy of the numerical solution. The higher-order grid technique in CF D extrapolates the values of the original low-resolution grid and fills in new nodes by some mathematical difference or interpolation techniques on top of the existing grid. The numerical solution with higher accuracy is transferred to the high-resolution grid, which makes the accuracy of the numerical solution effectively improved.