|
[Sponsors] |
March 4, 2019, 15:46 |
NACA 0012 low speed validation problem
|
#1 |
New Member
Join Date: Mar 2019
Posts: 7
Rep Power: 7 |
Hi everyone,
I am modelling a NACA 0012 airfoil using CFX at velocity 1.15 m/s, 1.55 deg AoA in air at 20 deg C (Re = 76104), but I am having issues validating the drag coefficient at this velocity as there seems to be about a 35% error when compared to NASA validation. The lift coefficient validates quite well. I have been using this for validation: https://turbmodels.larc.nasa.gov/naca0012_val.html Re for NASA validation = 6 million Am I using the wrong validation due to these differences in Re? Thank you! Last edited by 35matt215; March 4, 2019 at 18:24. |
|
March 4, 2019, 18:09 |
|
#2 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,850
Rep Power: 144 |
Re = 76000 is likely to be a transitional flow, with turbulence transitional the rear half of the foil or maybe fully laminar flow. That depends on the exact airfoil, upstream conditions, surface roughness and so on.
Re = 6M is definitely fully turbulent over the whole airfoil. They do not look like a good match to me.
__________________
Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum. |
|
March 4, 2019, 18:19 |
|
#3 |
New Member
Join Date: Mar 2019
Posts: 7
Rep Power: 7 |
Thanks for your reply!
So do you think it would be best if I look for papers with a smaller Re in order to validate my model with? |
|
March 4, 2019, 19:44 |
|
#4 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,850
Rep Power: 144 |
Reynolds number is probably the most fundamental parameter in fluid mechanics. If you don't match the Reynolds number then you are talking about completely different flows.
So in short, yes - you need to find data at the same Re number you are modelling. Here is a great resource for low Re airfoils - https://m-selig.ae.illinois.edu/uiuc_lsat.html
__________________
Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum. |
|
Tags |
airfoil, ansys, cfx, naca 0012 |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
MHD Flow in duct validation problem for low value of KINEMATIC viscousity | vipin1431 | OpenFOAM Verification & Validation | 0 | September 28, 2015 04:10 |
problem in validation on naca 0012 | mahdi_sangbori | FLUENT | 9 | August 27, 2015 17:40 |
Low pressure de Laval simulation convergence problem | heksel8i | FLUENT | 3 | July 22, 2013 11:28 |
low speed compressible flow | lily | CFX | 2 | November 16, 2005 06:15 |
NACA 0012 data for Low Re | Khurram | Main CFD Forum | 5 | May 10, 2005 12:05 |