In this part,
we are going to talk about the behaviour of airflow wing NACA_12
with an incoming transonic flow(Mach=0.85).We used an unstructured
grid for this simulation.This study show the differents caracteristics
for the flow with differents attack angles.In the second time we
present the effect of this evolution in the pressure-coefficient
(Kp) and the coefficient lift .
1) THE UNSTRUCTUCTURED GRIDS:
In AVBP, we can use for meshing,stuctured and unstructured grids.For this
simulation we used the second one
who can take different polygons.The unstructured grids give a lot of flexibilities for complex configurations but require
to add storage for the list of element to vertex pointers and an overhead for first looking up the number of the forming nodes in the table before loading the corresponding solution values(indirect addressing).The mesh generation algorithms for triangular and tetrahedral meshes for Euler are robust and mostly automated.
2)THE NACA_12 SIMULATIONS:Grid for NACA_12 simulation
We present and analyse the isopressure simulations because the distribution of pressure create the lift force.
Criterion convergence for all simulation is around 10-7
analysis we can say and see we have a shock wave for each incidence angle
and this wave move on the extrados wall.For the Angle_0 we have two shock
waves and they are antisymmetric,it is the fact we are an attack and a
wing symmetric.For the other angle until the take down we have the shock
in antisymmetric with attack angle.
After the "take down "(Attack Angle_25)we have a distribution of the pressure very differente,in the attack edge a great pressure density and near the leak edge a great loss pressure.This importance difference occurs "the take down".
We can say in the first time we obtained goods results for the incoming transonic NACA_12 simulation .We have a shock for a transonic flow like the theory and the differents experiences.But we obtain a take down point at 25 degrees whereas we should have around 17degrees.This fact is that we do not worry about the layout boundary.
In did our simulation resolve the Euler equation.In perfect fluide,there is a solution for Euler equation
drawing the flow around an obstacle.This solution is an approximation of the Navier-Stokes equations available
almost everywhere in stead of near the wall.And too AVBP code treate the Euler equation with a good precision,that why we can represent the behaviour of the wing in differente flow.