[mtheory]

Hi,


I am new to CFD simulations and I would like to as some questions. For an university project I have to validate a mesh against experimental results (lift coefficient and drag coefficient) of a NACA63-415 airfoil.



The experimental results I have found were obtained with an airfoil having a chord length of 0.606m, Re=1.6e6 and inlet velocity 40 m/s.



For the cfd simulations, can I use an airfoil with a 1m chord? I would use the same Reynolds number changing the inlet velocity.


Thanks in advice.

[aerosayan]

Originally Posted by mtheory

For the cfd simulations, can I use an airfoil with a 1m chord?

Nope.

Even though most aerofoil data is non-dimensional, and represented in non-dimensional units like x/c vs CL or x/c vs CD.

Not because you can't approximate the results correctly, but because when you report or publish your findings, you're gonna confuse the heck out of your supervisors, examiners, publication editors, readers, etc. etc. etc. Almost everyone is gonna doubt your results, even if they're correct. They'll have an internal bias against your results, as they won't trust it. Even if they do, when they try to use it for their research, they're gonna possibly misinterpret things, and ruin their experiments.

Since it's CFD, you can easily make the dimensions same as the real model.

Make it easy for the reader to understand your work. Keep things consistent, and do as much as you can to make it an enjoyable experience for your reader.


Keep It Simple.

[LuckyTran]

CFD is a situation where you can very easily use whatever dimensions you want, so do the right thing and use the ones from the experiment.

[aero_head]

Originally Posted by mtheory

Hi,


I am new to CFD simulations and I would like to as some questions. For an university project I have to validate a mesh against experimental results (lift coefficient and drag coefficient) of a NACA63-415 airfoil.



The experimental results I have found were obtained with an airfoil having a chord length of 0.606m, Re=1.6e6 and inlet velocity 40 m/s.



For the cfd simulations, can I use an airfoil with a 1m chord? I would use the same Reynolds number changing the inlet velocity.


Thanks in advice.

You can't do this directly as you describe, but there is a way. If you really want to use 1 m, look up modelling an similitude parameters (Buckingham's Pi Theorem) and solve that way.