Convection-diffusion Problems P <sub> 1 </ Sub> Non-conforming Element Streamline Diffusion Method

In this paper, P₁ - noncomforming finite element approxin-ation to the convection-diffusion problems are studied with streamline-diffusion method. By introducing some novel techniques and using typical characteristics of the element itself, the corresponding optimal error estimates are obtained under weaker conditions (the choice of the parameterδ_K has nothing to do with the perturbation parameterεand the inverse estimate coefficient parameterμin finite element spaces), whichimproves the results of in previous literature. Thus applicable scope of noncomforing element methods is enlarged.