The Density of Compressible Flow
 

I have done some runs of known geometries (naca, circle..) using a solver of euler equation (compressible flow). I saw in all these that while pressure near wall is ok (brush in wall, (the contour lines input the wall)), the density appear other behavior (near wall create as a layer with larger density). The contour lines of density do not input the wall. Also it appeared that density appear some instabilities.

What can be occured here? It is normal behaviour this?

Here, i must refer that use linear elements (straight sides) and reflected boundary conditions as walls. Also, the values of ghost elements took by the edge of wall (finite element) and not by extrapolation (finite volume).