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Re:Eighty Years of the Finite Element Method (2022) by akomtu on Saturday November 02, 2024 @06:06PM (#42029540)
Could you write a blogpost-style article on how to model the shallow water wave equation on a sphere? The article would start with the simplest possible method, something that could be implemented in short C program, and would continue with a progressively more accurate and complex methods.
Re:Eighty Years of the Finite Element Method (2022) by neumann on Saturday November 02, 2024 @06:55PM (#42029835)
If you are interested in this, I'd recommend following an openfoam tutorial, c++ though.

You could do SWE with finite elements, but generally finite volumes would be your choice to handle any potential discontinuities and is more stable and accurate for practical problems.

Here is a tutorial. https://www.tfd.chalmers.se/~hani/kurser/OS_CFD_2010/johanPi...

Re:Eighty Years of the Finite Element Method (2022) by akomtu on Sunday November 03, 2024 @03:52PM (#42036017)
I'm looking for something like this, but more advanced. The common problem with such tutorials is that they stop with the simplest geometry (square) and the simplest finite difference method.

What's unclear to me is how do I model the spherical geometry without exploding the complexity of the solution. I know that a fully custom mesh with a pile of formulas for something like beltrami-laplace operator would work, but I want something more elegant than this. For a example, can I use the Fibbonacci spiral to generate a uniform spherical mesh, and then somehow compute gradients and the laplacian?

I suspect that the stability of FE or FV methods is rooted in the fact that the FE functions slightly overlap, so computing the next step is a lot like using an implicit FD scheme, or better, a variation of the compact FD scheme. However I'm interested in how an adept in the field would solve this problem in practice. Again, I'm aware that there are methods of solving such systems (Jacobi, etc.), but those make the solution 10x more complex, buggier and slower.

Re:Eighty Years of the Finite Element Method (2022) by fastasucan on Saturday November 02, 2024 @08:34PM (#42030321)
Interesting that this reads almost like an chatgpt prompt.
Re:Eighty Years of the Finite Element Method (2022) by gwern on Saturday November 02, 2024 @09:37PM (#42030573)
Lazy people have been lazy forever. I stumbled across an example of this the other day from the 1990s, I think, and was shocked how much the student emails sounded like LLM prompts: https://www.chiark.greenend.org.uk/~martinh/poems/questions....
Re:Eighty Years of the Finite Element Method (2022) by MichaelZuo on Saturday November 02, 2024 @10:20PM (#42030759)
It reminds me of the old joke that half of the students are below average…
Re:Eighty Years of the Finite Element Method (2022) by wombatpm on Sunday November 03, 2024 @12:42AM (#42031213)
Expect in Lake Woebegone, all of the children are above average
Re:Eighty Years of the Finite Element Method (2022) by meindnoch on Sunday November 03, 2024 @05:09AM (#42032198)
But that's not true, unless by "average" you mean the median.
Re:Eighty Years of the Finite Element Method (2022) by KeplerBoy on Sunday November 03, 2024 @05:29AM (#42032274)
Normally, it's all the same.
Re:Eighty Years of the Finite Element Method (2022) by meindnoch on Sunday November 03, 2024 @06:08AM (#42032385)
Only if the distribution has zero skewness.

Unless "normally" you mean the normal distribution, which indeed has zero skewness.

Re:Eighty Years of the Finite Element Method (2022) by KeplerBoy on Sunday November 03, 2024 @01:47PM (#42035155)
Yes, it was a admittedly bad pun.
Re:Eighty Years of the Finite Element Method (2022) by pixelpoet on Sunday November 03, 2024 @03:55AM (#42031920)
At least those had some basic politeness. So often I'm blown away not only how people blithely write "I NEED HELP, GIMME XYZ NOW NERDS" but especially how everyone is just falling over themselves to actually help! WTF?

Basic politeness is absolutely dead, nobody has any concept of acknowledging they are asking for a favour; we just blast Instagram/TikTok reels at top volume and smoke next to children and elderly in packed public spaces etc. I'm 100% sure it's not rose-tinted memories of the 90s making me think, it wasn't always like this...

Re:Eighty Years of the Finite Element Method (2022) by CamperBob2 on Sunday November 03, 2024 @12:44PM (#42034612)
"As an AI language model, I am happy to comply with your request ( https://chatgpt.com/share/6727b644-b2e0-800b-b613-322072d9d3... ), but good luck finding a data set to verify it, LOL."
Re:Eighty Years of the Finite Element Method (2022) by sampo on Sunday November 03, 2024 @01:21PM (#42034916)
> Could you write a blogpost-style article on how to model the shallow water wave equation on a sphere?

Typically, Finite Volume Method is used for fluid flow problems. It is possible to use Finite Element Methods, but it is rare.