Airfoils in Deal.ii

[The Pilgrim]

Hi all I am writing or trying to write something exiciting using deal.ii and as a test of what I have done I wish to solve an airfoil case for a NACA 2408 chord length 1m in 2D. I want to know in general how the solution should flow for example import geometry > mesh geometry > create Dofs etc etc.....

To give a bit of context I have written substantial bindings to the deal.ii repo in python over and above what deal.ii has covered itself in python. I want to test my bindings. However the solutions I am implementing right now are akin to blow ups. compressible flow, rho blows up and incompresible flow I dont get sensible p, u solvers. I think I am missing a solution step which is why the problem might be ill conditioned. Some help might go a long way here.

Best

Gaurang

[blais...@gmail.com]

Dear Gaurang,

It would help if you could provide us with more information as to what kind of solver you are trying to implement.

Compressible:

- Is it an ideal fluid solver (Euler) or a full Navier-Stokes? How do you manage the non-linear terms? What are the boundary conditions you are imposing for the pressure, velocity and density? Is it isothermal or not?

Incompressible:

- How are you solving the saddle-point problem (stabilization, direct solver, schur complement, etc.)? What type of elements are you using? 

Overall, it will also depend on the Reynolds number you are simulating. Is your simulation transient or steady-state?

With this, it might be easier to help you. Otherwise, it is not really possible to provide guidance. Understand that deal.II is not a CFD solver but a framework to enable you to build your own solvers. In lethe we have an example that is a simulation of the flow around an airfoil (see https://chaos-polymtl.github.io/lethe/documentation/examples/incompressible-flow/2d-naca0012-low-reynolds/2d-naca0012-low-reynolds.html ) this may help you in the right direction.

Cheers

Bruno

[Wolfgang Bangerth]

On 9/28/25 05:42, The Pilgrim wrote:
>
> To give a bit of context I have written substantial bindings to the
> deal.ii repo in python over and above what deal.ii has covered itself in
> python.

Separate from the other questions Bruno has already addressed, we would
of course be very happy if you contributed whatever bindings you have
written! If you're unsure how to do that, take a look here:
https://dealii.org/community/

Best
W.