Fix vortex street elixir

[efaulhaber]

The elixir computed the kinematic viscosity, but then incorrectly used it as dynamic viscosity.
This resulted in an incorrect Reynolds number of ~180. I fixed the calculation and changed the Reynolds number in the elixir to 200 to produce similar results.

[github-actions]

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[DanielDoehring]

Ah yeah mea culpa, I did not normalize density to 1 here 😬

[efaulhaber]

I was wondering why you vary the density at a constant pressure. Seems more common to do the opposite.

[efaulhaber]

I just changed it to use constant density.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.93%. Comparing base (f76ccaf) to head (c198d8f).
Report is 6 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2360   +/-   ##
=======================================
  Coverage   96.93%   96.93%           
=======================================
  Files         500      500           
  Lines       41499    41499           
=======================================
  Hits        40226    40226           
  Misses       1273     1273           

Flag	Coverage Δ
unittests	96.93% <ø> (ø)

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[ranocha]

Thanks for fixing this issue! Some tests fail; could you please update them as required?
@DanielDoehring Could you please revies this PR?

[DanielDoehring]

I was wondering why you vary the density at a constant pressure. Seems more common to do the opposite.

Yeah probably I was looking at some incompressible flow example, where the only solution fields are pressure and velocity. Thanks for fixing this!

[DanielDoehring]

Thanks! Looks good to me. The error values change that drastic because density is now 1 and not~0.41 what it was before.

[ranocha]

Thanks!