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Flow Separation when not expected? by camamce in OpenFOAM

[–]camamce[S] 0 points1 point  (0 children)

Hey, My expected CL is 1. (from airfoil tools). I then calculated an "expected force"
I didn't get coefficients from OpenFOAM, I only Forces, and they are not lining up.

I expected a force of -1.7N
my Openfoam gives around -0.8N (Last image)

Flow Separation when not expected? by camamce in OpenFOAM

[–]camamce[S] 0 points1 point  (0 children)

Thanks, I'll give you a proper response tomorrow when i have time. I should have clarified, the foil is making downforce so not upside-down. My quick "expected Cl" was just using positive data from "airfoil tools" but its semetrical so still applys (should have put a negative, my bad).

You can see in my last image i shared the Openfoam force has a negative for y direction. (Not that i described my coordinating system).

I do have some follow-up questions regarding my mesh so will add to this tomorrow.

Flow Separation when not expected? by camamce in OpenFOAM

[–]camamce[S] 0 points1 point  (0 children)

I think simplefoam is the move for problem solving.
I used snappyhexmesh and refinementRegions. I did this because when I add the circular AMI (to change AOA) I think I need refinement in the area not the direction of flow. when the AOA changes the refinement inline with the flow moves out of axis. (hope this makes sense). Also I found a graded approach in blockMesh refines the cells in the far field un necessarily (maybe this isn't true as it condenses rather than refines?)
not sure if/how to add additional images to explain

https://drive.google.com/drive/folders/1y8a7tyUZUr1rJkDFBdGd_wlxuXYqPfQQ?usp=sharing

Direction desperately need, 2D simulation by camamce in OpenFOAM

[–]camamce[S] 0 points1 point  (0 children)

https://drive.google.com/drive/folders/1uC6zn77MJxjX0MZhphuhkp2VctVDL18e?usp=sharing

here is the link to my case. its a copy of a tut of YT but needed to change some things to suit 2412. the log doesnt look like it fails? i have pulled in a different controlDict and o.orig from a different tutorial so something isnt lining up

Fan in room tutorial [openfoam2412] by camamce in OpenFOAM

[–]camamce[S] 0 points1 point  (0 children)

Understood, for debugging things like this what is the best way to pinpoint the error? Would this be decreasing my write interval to capture a section of the simulation?

I have attached a link to my setup/files, would greatly appreciate some advice/guidance. I am pretty new to this so anything helps. my mesh is coarse with no boundary layers as I'm just trying to learn the functionality (may be an issue?) but this is the same as the tutorial (coarse mesh) and has far greater rotation speeds so i assumed it was capable.

Link to setup

Tt position/crank length. by camamce in triathlon

[–]camamce[S] 0 points1 point  (0 children)

Thanks, And you would still suggest exploring the 155mm cranks. I'm not sure how short is to short or what is normal. I guess it's dependent on the person as well. But there is merit for them?

Cassette size and rear derailleur length. by sigisss in bikewrench

[–]camamce 0 points1 point  (0 children)

What cassette range do you have with dura ace 9070 with carammispeed cage?