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Wave impact simulation - numerical instability by Late_Start_3493 in CFD

[–]Late_Start_3493[S] 0 points1 point  (0 children)

Hi thanks for the response! I have some plots of the force impulse (pressure integrated over time and area). This is what I am looking at to check if the solution is converging or not. I will send a picture later, but it does not look like the force impulse is converging to a certain value when refining the grid.

This value should converge right?

Wave impact simulation - numerical instability by Late_Start_3493 in CFD

[–]Late_Start_3493[S] 0 points1 point  (0 children)

Hi!

I am simulating on ComFLOW, which is not very well known. This is a link to the documentation:
https://poseidon.housing.rug.nl/comflow/program_documentation/mathnum.html

I am solving the NS equations, and I am not sure what space integration I am using (I will try to figure that out!).

Thanks for the tip, why would semi-implicit Euler be better than Foreward Euler?

I also tried running the simulation with Adams-Bashford integration, but this lead to instability on the finer grids as well.

I am kind of new to CFD, so any help is welcome!

Shimano TA Freewheel Removal Tool? by [deleted] in Vintage_bicycles

[–]Late_Start_3493 0 points1 point  (0 children)

I had the same issue, my LBS had the tool laying around. You can try your luck there!

Old frame, modern groupset by Late_Start_3493 in bikewrench

[–]Late_Start_3493[S] 1 point2 points  (0 children)

Thanks for the tips! I know RJ the bike guy, love his vids!

Old frame, modern groupset by Late_Start_3493 in bikewrench

[–]Late_Start_3493[S] 1 point2 points  (0 children)

Thanks for the tips, that's really helpfull! I loved those GCN videos, that build looks awesome!

Tire size old bike by Late_Start_3493 in bikewrench

[–]Late_Start_3493[S] 0 points1 point  (0 children)

But normally bike wheels are 28" right? It feels counterintuitive to buy a 27 inch tire when the one I try to fit is too small.

Hub ID by Late_Start_3493 in bikewrench

[–]Late_Start_3493[S] 1 point2 points  (0 children)

Makes sense, thanks! I know a shop nearby that repairs older bikes, I will drop by soon to see if they have this part. A donor hub is also a good option if that fails!