[carp]

Good evening,

I've seen several topics regarding a mesh for a tandem airfoil flow problem, but nevertheless I couldn't find a proper solution for my own problem.

What I'm trying to do is to place a airfoil very close to another one (1 to 3 chord lengths). Where I find the trouble is with the meshing part of the trailing airfoil. I've tried placing a c-shaped mesh around it (see the picture), but then the transition from the leading airfoil mesh to the trailing will become very nasty.

Does someone have a better idea? Many thanks in advance!

Kind regards,
Casper

[carp]

Hello all,

I've given it a shot and came up with something like this (see att.). It still does not look very nice, but I hope it'll do. Do you guys think it's ok too?

The new problem that came up now is while solving the flow, fluent gives me the reversed flow on .. faces error.

My outlet boundary condition is a pressure outlet, but the issue is here that my drag and lift convergences explode. Could this be solved by extending the outlet? Now it's about 20 chord lengths from the tail of the last airfoil to my outlet boundary.

Thanks for any answer!

[-mAx-]

-Regarding your mesh, I would do another split between both airfoils.
With this new region, you will be able to get a smoother mesh gradient from first trailing's edge
-reversed flow is just a warning, you may let iterate.
Are your pressure and velocity distribution realistic?
Sans titre.jpg

[carp]

Thanks! By decreasing the relaxation factors a little bit my solution got much better. But I've made an new grid using your suggested split in between and also smoother transitions between other regions.With this grid there was no need to adjust the relaxation factors.

I've included a picture of the new grid, just in case somebody wants to make a tandem NACA airfoil! Thanks max!

[-mAx-]

Thanks for your feedback