The abstract $L^2$-norm error estimate of nonconforming finite element method is established. The uniformly $L^2$-norm error estimate is obtained for the nonconforming finite element method for the second order elliptic problem with the lowest regularity, i.e., in the case that the solution $u∈H^1(Ω)$ only. It is also shown that the $L^2$-norm error bound we obtained is one order higher than the energe-norm error bound.
}, issn = {1991-7139}, doi = {https://doi.org/2000-JCM-9041}, url = {https://global-sci.com/article/85550/the-lsup2sup-norm-error-estimate-of-nonconforming-finite-element-method-for-the-2nd-order-elliptic-problem-with-the-lowest-regularity} }