非结构网格上新型的NND有限元格式

张涵信发展的ＮＮＤ差分格式是由中心差分格式，二阶迎风格式和一阶迎风格式混合组成的杂交型格式。众所周知，和中心差分格式相对应的是Ｇａｌｅｒｋｉｎ有限元格式。通过对中心型有限元格式加修正项的方法本文成功地构造出二阶迎风型有限元格式和一阶迎风型有限元格式。

A New NND Finite Element Scheme on Unstructed Grid

The NND finite element scheme developed by Zhang Hanxin is a mixed scheme containing central difference scheme,second order upwind scheme and first order upwind scheme.Adding a corrected term to the central finite element scheme,the second order and first order finite element schemes are constructed.The one side finite element calculation of the derivative on the unstructed scheme makes the judgement of the upstream regions and downstream regions possible.Combining these schemes,a new non oscillatory,containing no free parameter and dissipative scheme,i.e.NND finite element scheme is constructed at first time on unstructed grid.Several numerical results of typical examples for two dimensional inviscid compressible transonic and supersonic steady flow demonstrate that this is a new finite element scheme with high accuracy and high resolution for shock wave.Especially,intergrating with the adaptive remeshing technique,the satisfactory results can be obtained by this scheme.