Fix typos in m_viscous.fpp

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: sbryngelson

src/simulation/m_viscous.fpp

@@ -1564,12 +1564,12 @@ contains
         real(wp) :: divergence
         integer :: l, q ! iterators
 
-        ! zero the viscous stress, collection of velocity diriviatives, and spacial finite differences
+        ! zero the viscous stress, collection of velocity derivatives, and spatial finite differences
         viscous_stress_tensor = 0._wp
         velocity_gradient_tensor = 0._wp
         dx = 0._wp
 
-        ! get the change in x used in the finite difference equaiont
+        ! get the change in x used in the finite difference equation
         dx(1) = 0.5_wp*(x_cc(i + 1) - x_cc(i - 1))
         dx(2) = 0.5_wp*(y_cc(j + 1) - y_cc(j - 1))
         if (num_dims == 3) then