# Structured 2D Euler - wall boundary condition problem

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 March 17, 2018, 21:24 Structured 2D Euler - wall boundary condition problem #1 New Member   John Peralta Join Date: Mar 2018 Location: Paris Posts: 2 Rep Power: 0 Hi! I am currently writing a 2D structured cell-centered Euler code using the central spatial discretization scheme with scalar artificial dissipation (JST) and a simple explicit 5-stage R-K solver. Lately, I am stuck debugging the code (it blows up) and I am a bit frustrated so I wanted to ask you for any idea regarding how to fix my problem. I have implemented the supersonic inlet/outlet farfield boundary conditions (for start) and I am using an O-mesh. I observe that even though I have implemented the wall boundary conditions using ghost cells, the condition for zero-normal velocity on wall is not satisfied. I am getting a "blowing" velocity starting from leading edge and this produces a "cushion" that surrounds the airfoil (see attached screenshots). I am updating the boundary conditions as in the following pseudocode Code: ```// Desired values on BC wall face rBC = r[wallcell]; uBC = u[wallcell] - V[haloface]*nx[haloface]; vBC = v[wallcell] - V[haloface]*ny[haloface]; pBC = p[wallcell]; (V is the contravariant velocity and haloface is the same as the wallface with reversed (negative) face vectors) //Then the first layer of halo cells is r[halo1] = rBC; u[halo1] = 2*uBC - _u[wallcell]; v[halo1] = 2*vBC - _v[wallcell]; p[halo1] = pBC; //and the second r[halo2] = rBC; u[halo2] = u[halo1]; v[halo2] = v[halo1]; p[halo2] = pBC;``` Any idea on what I am missing will be appreciated! Thanks! Screenshots -> https://drive.google.com/open?id=16V...PaQUqi7BtAGR1Q Last edited by Peralta; March 18, 2018 at 06:00. Reason: Included functioning link to screenshots.