Fix bug in 2D CEE HLLE Noncartesian flux

[DanielDoehring]

In #1692 there is unfortunately a bug.
The correct velocity magnitude to be used is found in the 3D version

Trixi.jl/src/equations/compressible_euler_3d.jl

Line 1431 in 276dc3c

v_roe_mag = v1_roe^2 + v2_roe^2 + v3_roe^2

and the 2D version is wrong:

Trixi.jl/src/equations/compressible_euler_2d.jl

Line 1354 in 276dc3c

v_roe_mag = (v1_roe * normal_direction[1])^2 + (v2_roe * normal_direction[2])^2

[github-actions]

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[DanielDoehring]

Interestingly (and unfortunately) this was not detected by the consistency checks

Trixi.jl/test/test_unit.jl

Lines 908 to 916 in 276dc3c

	normal_directions = [SVector(1.0, 0.0),
	SVector(0.0, 1.0),
	SVector(0.5, -0.5),
	SVector(-1.2, 0.3)]
	for normal_direction in normal_directions
	@test flux_hlle(u, u, normal_direction, equations) ≈
	flux(u, normal_direction, equations)
	end

but instead by the rotation test added in #1708.

[sloede]

Nice catch! Code LGTM, but it would be good to get a review from someone familiar with the HLLE flux.

[ranocha]

Thanks

[DanielDoehring]

Nice catch! Code LGTM, but it would be good to get a review from someone familiar with the HLLE flux.

Credit goes to @ranocha for being strict about the test : #1708 (comment)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (276dc3c) 74.61% compared to head (a57f7f9) 83.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1719      +/-   ##
==========================================
+ Coverage   74.61%   83.00%   +8.39%     
==========================================
  Files         431      431              
  Lines       34600    34665      +65     
==========================================
+ Hits        25815    28772    +2957     
+ Misses       8785     5893    -2892     

Flag	Coverage Δ
unittests	83.00% <100.00%> (+8.39%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
src/equations/compressible_euler_2d.jl	96.81% <100.00%> (+0.72%)	⬆️

... and 107 files with indirect coverage changes

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