implement sod shock tube initial data

src/SRHD/initialdata.jl

@@ -163,19 +163,16 @@ end
 function initialdata_equation_of_state(
     ::Val{:sod_shocktube}, eos::EquationOfState.IdealGas, mesh)
 
-  TODO()
-
+  # from EFL paper: arxiv 2202.08839
   @unpack x = get_static_variables(mesh.cache)
   (xmin, xmax), = mesh.extends
 
   @toggled_assert isapprox(xmin, -1.0) && isapprox(xmax, 1.0)
-  @toggled_assert eos.gamma == 5/3
+  @toggled_assert eos.gamma ≈ 1.4
   x0 = 0.0
-  # ρ0 = [ (xi < x0) ? 1.0  :  0.125  for xi in x ]
-  # v0 = [ (xi < x0) ? 0.0  :  0.0    for xi in x ]
-  # p0 = [ (xi < x0) ? 1.0  :  0.1    for xi in x ]
-
-  xl, xr = -0.5, 0.5
+  ρ0 = [ (xi < x0) ? 1.0  :  0.125  for xi in x ]
+  v0 = [ (xi < x0) ? 0.0  :  0.0    for xi in x ]
+  p0 = [ (xi < x0) ? 1.0  :  0.1    for xi in x ]
 
   (ρ0, v0, p0)
 end