Patch bubbles for advection-dominated problems

A novel variant of the \emph{residual-free bubble} method (RFB) for advection dominated problems is presented. Since the usual RFB still suffers from oscillations and strong under/overshoots, the bubble space is enriched by \emph{patch bubbles}, giving more freedom to the bubble space. We use a recursive and efficient approach to accurately compute the bubbles. Numerical experiments clearly demonstrate the superiority of our method compared to the standard RFB. The method is similar to the \emph{enhanced residual-free bubble} method (eRFB) proposed by Cangiani and S\"uli in 2005, but differs in the definition of the additional bubbles.