Mahantesh external flow analysis is air at sea level

Katagi (2015), the paper objective was to study the aerodynamics characteristic
of a flying wing using CFD techniques by identifying various parameters such as
the coefficient of lift, drag, pressure and moment.  These parameters were calculated under
different Mach number and different angle of attack so it can be properly
observe and analyzed.  In this work two
solvers have been used which are pressure based and density based solvers with
suitable turbulence models, which solves
RANS equations 9. As for its methodology, the
aircraft model was created using CATIA V5 and the grid generation process has
been carried using meshing tools like ICEM CFD 14, Pointwise and Workbench. Two
independent grids one with 2.5 million cells and 7.5 million cells are
conducted at Mach number = 0.13 and different angle of attack from -4° to
24°.  The results from both grids are
almost the similar. In ANSYS Fluent 14.0 simulation, the viscosity of the fluid
is considered in the flow domain and the working fluid used in this external
flow analysis is air at sea level condition. 
In the journal, there are three boundary location identify; inlet, wing
wall and symmetry. In the initial stage running the oscillations in the
solution will be more, after some iteration the solution will become stable
then time courant number is increased for faster convergence. For this work Spalart-Allmars
model is applied. For the coefficient of lift, as the angle of attack increases
pressure at the lower surface of the wing increases and on the upper side it
decreases. That’s why due to this pressure difference lift increases. For the
coefficient of drag, as the angle of attack increases the area opposed to the
flow of air increases. Finally, for the coefficient of moment as the angle of
attack increases pithing moment coefficient increases due to instability during
flight take-off and landing.