本文研究半线性分数阶扩散问题的Galerkin时空有限元方法,该方法在空间连续,而在时间上间断.将有限元与有限差分方法相结合,充分利用拉格朗日插值多项式在Radau点处的特性,给出弱解的存在唯一性证明,且不需对时空网格施加任何限制.通过引入椭圆投影算子,详细导出了最优阶L∞(L^2)模误差估计.
A Galerkin space-time finite element method, continuous in space but discontinuous in time, for the semilinear fractional diffusion problem is discussed. Based on a combination of finite element and finite difference techniques,taking full advantage of useful properties of Lagrange interpolation polynomials at the Radau points of each I,, the existence and uniqueness of the weak solution are proved without any assumption on the choice of space-time meshes. After introduce an appropriate elliptic projection operator,the optimal order error estimate in L^∞ (L^2) is derived in detail.