Apply suggestions from code review

Co-authored-by: Daniel Doehring <daniel.doehring@rwth-aachen.de>

examples/tree_2d_dgsem/elixir_mhdmultiion_collisions.jl

@@ -53,7 +53,7 @@ equations = IdealGlmMhdMultiIonEquations2D(gammas = (5 / 3, 5 / 3),
                                            gas_constants = (1.0, 1.0), # [nondimensional]
                                            molar_masses = (1.0, 1.0), # [nondimensional]
                                            ion_ion_collision_constants = [0.0 0.4079382480442680;
-                                                                          0.4079382480442680 0.0], # [nondimensional] (computed with eq (4.142) of Schunk&Nagy (2009))
+                                                                          0.4079382480442680 0.0], # [nondimensional] (computed with eq (4.142) of Schunk & Nagy (2009))
                                            ion_electron_collision_constants = (8.56368379833E-06,
                                                                                8.56368379833E-06), # [nondimensional] (computed with eq (9) of Ghosh et al. (2019))
                                            electron_pressure = electron_pressure_constantTe,
@@ -81,15 +81,15 @@ function temperature1(u, equations::IdealGlmMhdMultiIonEquations2D)
     rho_1, _ = Trixi.get_component(1, u, equations)
     p = pressure(u, equations)
 
-    return p[1] / rho_1 / equations.gas_constants[1]
+    return p[1] / (rho_1 * equations.gas_constants[1])
 end
 
 # Temperature of ion 2
 function temperature2(u, equations::IdealGlmMhdMultiIonEquations2D)
     rho_2, _ = Trixi.get_component(2, u, equations)
     p = pressure(u, equations)
 
-    return p[2] / rho_2 / equations.gas_constants[2]
+    return p[2] / (rho_2 * equations.gas_constants[2])
 end
 
 initial_condition = initial_condition_slow_down

src/equations/ideal_glm_mhd_multiion.jl

@@ -518,8 +518,7 @@ where ``M_k`` is the molar mass of ion species `k` provided in `equations.molar_
 with the so-called reduced temperature ``T_{k k'}`` and the ion-ion collision constants ``\tilde{B}_{kk'}`` provided
 in `equations.ion_electron_collision_constants` (see [`IdealGlmMhdMultiIonEquations2D`](@ref)).
 
-The additional coefficient ``\bar{\nu}^1_{kk'}`` is a non-dimensional drift correction factor proposed by Rambo and 
-Denavit.
+The additional coefficient ``\bar{\nu}^1_{kk'}`` is a non-dimensional drift correction factor proposed by Rambo and Denavit.
 
 References:
 - P. Rambo, J. Denavit, Interpenetration and ion separation in colliding plasmas, Physics of Plasmas 1 (1994) 4050–4060.

src/equations/ideal_glm_mhd_multiion_2d.jl

@@ -32,8 +32,8 @@ ratios `charge_to_mass` should be passed as tuples, e.g., `gammas=(1.4, 1.667)`.
 The ion-ion and ion-electron collision source terms can be computed using the functions 
 [`source_terms_collision_ion_ion`](@ref) and [`source_terms_collision_ion_electron`](@ref), respectively.
 
-For ion-ion collision terms, the optional arguments `gas_constants`, `molar_masses`, and `ion_ion_collision_constants` 
-must be provided.  For ion-electron collision terms, the optional arguments `gas_constants`, `molar_masses`, 
+For ion-ion collision terms, the optional keyword arguments `gas_constants`, `molar_masses`, and `ion_ion_collision_constants` 
+must be provided.  For ion-electron collision terms, the optional keyword arguments `gas_constants`, `molar_masses`, 
 `ion_electron_collision_constants`, and `electron_temperature` are required.
 
 - **`gas_constants`** and **`molar_masses`** are tuples containing the gas constant and molar mass of each