Compressible Euler Quasi-1D

[KrisshChawla]

Adding quasi 1d compressible Euler equations, as well as an entropy conservative flux for the system.

[github-actions]

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Created with ❤️ by the Trixi.jl community.

[codecov]

Codecov Report

Attention: 11 lines in your changes are missing coverage. Please review.

Comparison is base (14796ea) 69.41% compared to head (db0e311) 96.23%.

Files	Patch %	Lines
src/equations/compressible_euler_quasi_1d.jl	91.34%	11 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1757       +/-   ##
===========================================
+ Coverage   69.41%   96.23%   +26.82%     
===========================================
  Files         433      436        +3     
  Lines       34964    35188      +224     
===========================================
+ Hits        24270    33862     +9592     
+ Misses      10694     1326     -9368     

Flag	Coverage Δ
unittests	96.23% <92.09%> (+26.82%)	⬆️

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[jlchan]

Looks good! I added a few suggestions for clarifying comments, and had one question about the correctness of the cons2entropy function.

Please also comment with the value of dS/dt from the entropy conservation test when you get a chance.

[KrisshChawla]

The entropy conservation test elixir_euler_quasi_1d_ec.jl consisting of a discontinuous density function and nozzle width on a periodic domain results in an entropy error of ∑∂S/∂U ⋅ Uₜ : -3.63598041e-15.

[DanielDoehring]

Thanks for the contribution! I left some suggestions and two possible points for discussion.

Please consider also adding consistency checks for the numerical fluxes, see

Trixi.jl/test/test_unit.jl

Lines 628 to 638 in 5c08cf4

	@timed_testset "Consistency check for HLL flux (naive): CEE" begin
	flux_hll = FluxHLL(min_max_speed_naive)
	# Set up equations and dummy conservative variables state
	equations = CompressibleEulerEquations1D(1.4)
	u = SVector(1.1, 2.34, 5.5)
	orientations = [1]
	for orientation in orientations
	@test flux_hll(u, u, orientation, equations) ≈ flux(u, orientation, equations)
	end

[jlchan]

Thanks for the review, Daniel!

[jlchan]

@KrisshChawla did you get a chance to test if @DanielDoehring's suggestion was faster or slower?

[KrisshChawla]

if direction == 1 for boundary_condition_slip_wall resulted in slightly faster calculation times by fractions of a millisecond for calculating boundary flux compared to isodd(direction) such as when using the boundary condition in elixer_euler_quasi_1d_ec.

[jlchan]

if direction == 1 for boundary_condition_slip_wall resulted in slightly faster calculation times by fractions of a millisecond for calculating boundary flux compared to isodd(direction) such as when using the boundary condition in elixer_euler_quasi_1d_ec.

Thanks for checking!

The failing tests seem to be related to other test failures (e.g., #1762 and #1759). Let's wait to see if we can figure out why these are failing - they don't have anything to do with these changes though so we shouldn't need to update this PR any more.

[DanielDoehring]

I changed two comments.