# I have trouble with plots

I’m student in aerospace engineering department and new on using CFD Programs. My aerodynamic teacher gaved me a project about analyzing an airfoil on CFD and comparing the results with other resullts that I reached with thin airfoil theory (lift coefficients, moment coefficients about quarter chord etc.). And I’m trying to do it with following the steps of “Incompressible Turbulent Airflow Around a Spoiler” tutorial. I created external flow volume, applied boundary layers, material etc. , did region refinements and then meshed and ran the simulation just as the tutorial says. But as the document I uploaded says I should have determined lift coefficient, moment coefficient by applying Reynolds Numbers. And I have no idea how do I determine them or apply Reynolds Num. The plots that simulation showed me are just about U,V,W speeds and pressure. I need help about this. Thanks.

Hi there!

The Reynolds number is related to the characteristic length of your wing (the chord) and the inlet flow speed. So, to vary the Reynolds number, you should change the inlet speed, then there is no need to change the geometry.

It is also important to relate your Reynolds number with the flow regime (laminar, turbulent) and select a proper turbulence model for the simulation.

Please refer to some textbook on CFD modelling or look for similar works for the details on these aspects.

If you send a link to your project, we should be able to provide more suggestions. Specially, if you are going to compare to 2D results, you should create the 3D model accordingly.

Thank you so much, I handled the situation about Reynolds number thanks to your advice. But I couldn’t understand the plots that I get. I want to reach lift coefficient and moment coefficient. How do I do that?

What plots are you receiving?

Here are the all plots that I have

And here is my airfoil:

Hi!

You are showing me convergence plots. Show me the plot of the aerodynamic forces or coefficients so we know if you have converged values.

That is exactly what my problem is. I don’t know how to reach them in Simscale. And this force and coefficient plots are the main subject of my project which I am trying to reach.