Source Panel Method: Circular Cylinder

[@stuartmilam3437]

Simply an incredibly helpful compilation of tutorials. Well done.

[@JoshTheEngineer]

Thank you, much appreciated!

[@blackguardian89]

Finally! Thank you so much :) Can't wait for the next videos! Keep up the good work!

[@JoshTheEngineer]

You're welcome! They're coming soon!

[@calebtomes1285]

If I was given circulation values of 0,-1,-2,and -3 how would I get different streamline plots for the given values?

[@ruili9830]

Hi Josh, thank you for your video and codes. Hope you are well. I'm also working on coding of panel method. I found that in the seciton of calculating streamlines if you set the grid points as 30, 50, 70, etc you will get a strange plot with a straight line pointing to the circle. Do you know why this happens? Thank you very much!

[@JoshTheEngineer]

Good question Rui. That's actually the stagnation streamline, which is why it terminates on the cylinder (stagnation means there's no velocity, so it won't move anywhere once it hits the stagnation point). It just so happens that for nGridX/nGridY points of 30, 50, 70, etc., one of the streamlines hits the stagnation point and doesn't continue around the cylinder. Look at the "Ysl" variable for those grid sizes, and you'll see that one of them is zero, which means its on the centerline of the cylinder. You can use these values (30, 50, 70) if you change the slPct variable either up or down (e.g. from 0.3 to 0.35). The higher the value, the denser the streamlines. While looking at this in the code, I realized I have a bug that means you have to have square grids for the streamline computations, so I'll update that in a future version. Hope that answered your question!

[@ruili9830]

@@JoshTheEngineer Thank you Josh! It really helps!

[@ruili9830]

Hi Josh, thanks for the awesome video. So SPM cannot be used to calculate the lift force and you can only get the pressure distribution by this method? But doublet and source panel methods can be used for lift calculations? And drag force can be calculated only in 3D cases?

[@JoshTheEngineer]

You're welcome! Correct, you can't use the SPM to get lift. To get lifting flow, you'll need a vortex in the flow. That's why in the VPM, we construct the airfoil out of vortex panels instead of source panels. You won't be able to get drag from either the SPM or the VPM. To compute drag, you'll need to introduce viscous effects, which then gets into boundary layer computations, and is the topic of a whole separate set of videos. When you start getting into 3D calculations, then things are different and more confusing, since there are different kinds of drag. This, again, is an entirely separate topic that I may get into in the future.

[@ruili9830]

​@@JoshTheEngineer Thank you Josh!

[@kelvinjaramillo8007]

Thank you!! Very much.....

[@JoshTheEngineer]

You're welcome!

[@ИванНовожилов-э9з]

awesome!

[@JoshTheEngineer]

Thanks!

[@Gabriel-oo8em]

What happens when E is not real?? I mean Iij goes to infinity ...

[@hasanmutlu4304]

There is something wrong with your matlab code because it does not give the same numbers (CL,CD ,L) with python code.

[@redouanehemi9693]

the number of boundary points should be equal to the number of panel

[@JoshTheEngineer]

Not the way I define the geometry.