Universal High Order Subroutine with New Shock Detector for Shock   Boundary Layer Interaction
  The goal of this work is to develop a new universal high order subroutine for shock boundary layer interaction. First, an effective shock/discontinuity detector has been developed.The detector has two steps.The first step is to check the ratio of the truncation errors on the coarse and fine grids and the second step is to check the local ratio of the left and right slopes. The currently popular shock/discontinuity detectors can detect shock, but mistake high frequency waves and critical points as shock and then damp the physically important high frequency waves.Preliminary results show the new shock/discontinuity detector is very delicate and can detect all shocks including strong, weak and oblique shocks or discontinuity in function and the first, second, and third order derivatives without artificial constants, but never mistake high frequency waves and critical points, expansion waves as shock. This will overcome the bottle neck problem with numerical simulation for the shock-boundary layer interaction, shock-acoustic interaction, image process, porous media flow, multiple phase flow and anywhere the high frequency waves are important, but discontinuity exists and is mixed with high frequency waves. After detecting the shock we can then use one side high order scheme for shocks and high order central compact scheme for the rest if the shock is appropriately located. Then a high order universal subroutine for finite difference method is developed which can be used for any finite difference code for accurate numerical derivatives. 
M. Oliveria, P. Lu, X. Liu and C. Liu
physics.comp-ph