Running a case with simpleFoam

matteo_gautero

Hi to all,
sorry for my english. I have some problems with my case. I have to study the aerodynamic of an airplane at cruise speed and altitude; the cruise speed is 60 m/s at an altitude of 1500 m, so the Mach number is equal to 0.2, then I assume that it is an incompressible case. I create a domain where is located the airplane; in particular, the mesh is composed by 16 millions of tetrahedra and it's finer near the airplane, coarser near the surface of the domain. I'm running this case with simpleFoam solver because I'm interested to the steady state solution. I impose the following boundary conditions:

- wall: on the airplane surface (velocity=zero, grad(p)=0)
- slip: on the lateral surface of the domain
- inlet: I impose the velocity that is equal to the cruise speed (grad(p)=0).
-outlet: classic outlet where the pressure is defined; in this case I put the pressure equal to zero.

I don't set the pref and the initial value for the pressure in the internal field is zero. For the velocity, the internal field is set to 50 m/s.

For now I use a laminar flow, so I'm not interesting to calculate the turbolence yet. I set the value of the viscosity to 1.646e-05 (viscosity at the altitude) and I set the schemes for the simulation. I used the default schemes for the different variables, imposing gauss upwind for the div schemes that are not set.

The problem is that the residuals are not acceptable, they are too high, 10^-2 after 2000 iterations for the pressure. I think that is a problem due to the choises about the boundary conditions.

Can anyone help me?

Thanks in advance,
Matteo.