Validation plunging airfoil - Forces are wrong!!!
 

Dear all,

I have been trying to validate a plunging airfoil case with no success. Here are the specifications of my case:

1- I use a naca12 profile, trying to validate the plunging motion described by y(t) = amplitude * sin (omega * t). The simulations I am trying to validate against are from the paper by Liang et al. Computers & Fluids, Vol. 40. Issue 1, January 2011, Pages 236–248

2- I use pimpleDyMFoam (without turbulence model, i.e. laminar) with oscillatingLinearMotion ( attached is my constant/dynamicMeshDict file).
I used faceZone mWing; instead of cellZone mWing; because I have been having problems with this configuration. I created the faceZone using a topoSet dict using the patch of the airfoil as input.

my first question is: Is this wrong? to use faceZone instead of cellZone as the rotating zone? could this explain the huge differences I get when I compare the forces I obtain with OF and the paper I cited earlier?

As an example:

forces delivered by OF:
Cd_mean = 0.1788
Cl_mean = -0.0128

forces delivered (validated against experiments) by Liang et al:
Cd_mean = -0.0436
cl_mean = -0.0042

(attached is also the temporal variations of Lift, drag and momentum coefficients obtained using OF)

Any comment of help will be appreciated, especially from someone who is also trying to validate OF for moving airfoils.

best regards,

W

Hi all,

actually I solved that problem with the forces and I will post the solution soon.

Regards,
W

Hi W,

I am doing something very similar to yours, but instead I am modeling an oscillating hydrofoil using pimpleDyMFoam. I am facing issues with inaccuracy with the forces as well. Do you have any insight as you mentioned you have solve the problem.

Thanks,
Zoe

Solving the same problem
 

W,

Can you tell us how you solved the issue of high forces?

Thanks,
Pruthvi.