chemFoam tutorials: set ODE solver to seulex which performs best overall

tutorials/combustion/chemFoam/README

 Stiff chemistry solver validation test cases
 
 gri    : GRI-Mech 3.0. CH4 combustion, 53 species, 325 reactions
-
 h2     : H2 combustion, 10 species, 27 reactions
-
 nc7h16 : n-Heptane combustion, 544 species, 2446 reactions
-
 ic8h18 : iso-Octane combustion, 874 species, 3796 reactions
 
 Results interpreted in 'validation' sub-folder, where OpenFOAM results
-are compared against those predicted by Senkin (CHEMKIN II)
+are compared against those predicted by CHEMKIN II.
 
+Overall the best performing ODE solver is seulex followed closely by rodas32.

tutorials/combustion/chemFoam/gri/constant/chemistryProperties

@@ -33,7 +33,7 @@ EulerImplicitCoeffs
 
 odeCoeffs
 {
-    solver          rodas32;
+    solver          seulex;
     absTol          1e-12;
     relTol          1e-1;
 }

tutorials/combustion/chemFoam/h2/constant/chemistryProperties

@@ -33,7 +33,7 @@ EulerImplicitCoeffs
 
 odeCoeffs
 {
-    solver          rodas32;
+    solver          seulex; //rodas32;
     absTol          1e-12;
     relTol          1e-1;
 }

tutorials/combustion/chemFoam/ic8h18/constant/chemistryProperties

@@ -33,7 +33,7 @@ EulerImplicitCoeffs
 
 odeCoeffs
 {
-    solver          rodas32;
+    solver          seulex;
     absTol          1e-12;
     relTol          1e-1;
 }

tutorials/combustion/chemFoam/nc7h16/constant/chemistryProperties

@@ -33,7 +33,7 @@ EulerImplicitCoeffs
 
 odeCoeffs
 {
-    solver          rodas32;
+    solver          seulex;
     absTol          1e-14;
     relTol          1e-1;
 }