Code-equations/Gravitational-Potential-including-indirect-terms.md

@@ -67,19 +67,21 @@ $`\tilde \Phi_p = {{ G m_p} \over {r_p^3}}(\vec r_p \cdot \vec r)`$
 
  
 with $`\vec r_p`$ and $`\vec r`$ indicating the distance between the
-planet and the star and a disk element and the star. The second term is:
+planet and the star and a disk element and the star.  This term is always included in the simulation.
+
+The second term is:
 
 $`\tilde \Phi_d =   \vec a  \cdot \vec r `$
 
 where $`\vec a`$ is the acceleration of the primary due to the whole disk.
 
-When doing simulations in production mode such terms must be included in the computations. However, it may be useful to control the contribution from indirect terms. At this purpose the indirect terms may be de activated in the config file with the flag ``IndirectForces`` in the Referential group :
+When doing simulations in production mode such term can be  be included or not in the computations. We need to recall here that we neglet self-gravity, i.e. the contribution to the potential from direct gravitational influence of the disk on itself. Therefore considering the indirect contribution, which is proportional to the disk mass may be critical in certain situations (ex. vortex formation). At this purpose this specific indirect term may be de activated or not in the config file with the flag ``IndirectForces`` in the Referential group :
 
 ```
  Referential
     {
         Type Constant
-        IndirectForces false # true in production mode
+        IndirectForces false
         Omega 1
         NewOmega 0
     }