# Drag under Euler formulation

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 July 23, 2013, 10:42 Drag under Euler formulation #1 New Member   MENDES BORTOLAZZI Andre Join Date: Jun 2013 Posts: 7 Rep Power: 11 Hi developers, I would like to ask you how the drag of a profile is computed using Euler analysis. In another post, I've been told the total drag was computed by integrating over the surface, but how is the shear stress tension localy computed? Are the concepts of displacement thickness and momentum thickness employed? Thanks in advance, Andre

August 19, 2013, 13:32
#2
Super Moderator

Francisco Palacios
Join Date: Jan 2013
Location: Long Beach, CA
Posts: 404
Rep Power: 14
Hi Andre,
To compute the Drag (inviscid and viscous) we perform a direct integration of the forces on the surface. More details in http://su2.stanford.edu/documents/SU2_AIAA_ASM2013.pdf

And the subroutines in the code:
void CEulerSolver::Inviscid_Forces(CGeometry *geometry, CConfig *config)
void CNSSolver::Viscous_Forces(CGeometry *geometry, CConfig *config)

Best,
Francisco

Quote:
 Originally Posted by Bortolazzi Hi developers, I would like to ask you how the drag of a profile is computed using Euler analysis. In another post, I've been told the total drag was computed by integrating over the surface, but how is the shear stress tension localy computed? Are the concepts of displacement thickness and momentum thickness employed? Thanks in advance, Andre

 August 20, 2013, 09:14 #3 New Member   MENDES BORTOLAZZI Andre Join Date: Jun 2013 Posts: 7 Rep Power: 11 Hi Francisco, Thanks for your reply. In the end, I guess I was just strugling with spurious drag, because SU2 provided some small values for drag coefficient when running a bidimensional Euler analysis in low Mach flow (thus, no drag). I was confused, because the spurious drag was increasing with the angle of attack, but after some research, I found out this is the normal behaviour for numerical drag. Thanks again for your attention. Best regards, Andre