diff --git a/main_physics.idx b/main_physics.idx
index 2309f8a..1d79a89 100644
--- a/main_physics.idx
+++ b/main_physics.idx
@@ -488,3 +488,16 @@
 \indexentry{strength of the vortex tube|hyperpage}{43}
 \indexentry{stream function|hyperpage}{43}
 \indexentry{vorticity equation|hyperpage}{43}
+\indexentry{Cauchy's stress theorem|hyperpage}{43}
+\indexentry{stress tensor|hyperpage}{43}
+\indexentry{first viscosity coefficient|hyperpage}{44}
+\indexentry{second viscosity coefficient|hyperpage}{44}
+\indexentry{Navier-Stokes equations|hyperpage}{44}
+\indexentry{Navier-Stokes equations for incompressible flow|hyperpage}{44}
+\indexentry{kinematic viscosity|hyperpage}{44}
+\indexentry{characteristic length|hyperpage}{44}
+\indexentry{characteristic velocity|hyperpage}{44}
+\indexentry{characteristic length|hyperpage}{44}
+\indexentry{characteristic velocity|hyperpage}{44}
+\indexentry{Reynolds number|hyperpage}{44}
+\indexentry{similar|hyperpage}{44}
diff --git a/main_physics.ilg b/main_physics.ilg
index 1032c36..9e4190e 100644
--- a/main_physics.ilg
+++ b/main_physics.ilg
@@ -1,6 +1,6 @@
 This is makeindex, version 2.17 [TeX Live 2023] (kpathsea + Thai support).
-Scanning input file main_physics.idx....done (490 entries accepted, 0 rejected).
-Sorting entries.......done (4920 comparisons).
-Generating output file main_physics.ind....done (545 lines written, 0 warnings).
+Scanning input file main_physics.idx....done (503 entries accepted, 0 rejected).
+Sorting entries.......done (4815 comparisons).
+Generating output file main_physics.ind....done (555 lines written, 0 warnings).
 Output written in main_physics.ind.
 Transcript written in main_physics.ilg.
diff --git a/main_physics.ind b/main_physics.ind
index f9795e7..aa4848d 100644
--- a/main_physics.ind
+++ b/main_physics.ind
@@ -71,9 +71,12 @@
   \item Carnot cycle, \hyperpage{32}
   \item Carnot cylce, \hyperpage{32}
   \item Carnot's theorem, \hyperpage{32}
+  \item Cauchy's stress theorem, \hyperpage{43}
   \item CB, \hyperpage{28}
   \item Center of masses, \hyperpage{13}
   \item center of masses, \hyperpage{13}
+  \item characteristic length, \hyperpage{44}
+  \item characteristic velocity, \hyperpage{44}
   \item Charge conservation, \hyperpage{4}
   \item charm, \hyperpage{27}
   \item chemical equilibrium, \hyperpage{30}
@@ -180,6 +183,7 @@
   \item First law of thermodynamics in closed systems, \hyperpage{31}
   \item First law of thermodynamics in isolated systems, \hyperpage{31}
   \item First postulate, \hyperpage{14}
+  \item first viscosity coefficient, \hyperpage{44}
   \item flavors, \hyperpage{27}
   \item fluid, \hyperpage{16}
   \item flux, \hyperpage{4}
@@ -259,6 +263,7 @@
   \item Kelvin's circulation theorem, \hyperpage{42}
   \item Ket, \hyperpage{35}
   \item kets, \hyperpage{35}
+  \item kinematic viscosity, \hyperpage{44}
   \item kinetic coefficient of friction, \hyperpage{12}
   \item Kinetic energy, \hyperpage{13}
   \item kinetic energy, \hyperpage{13}, \hyperpage{41}
@@ -322,6 +327,8 @@
 
   \indexspace
 
+  \item Navier-Stokes equations, \hyperpage{44}
+  \item Navier-Stokes equations for incompressible flow, \hyperpage{44}
   \item Neutral, \hyperpage{30}
   \item Newton's law of cooling, \hyperpage{29}
   \item Newton's laws, \hyperpage{12}
@@ -419,7 +426,7 @@
   \item resistivity, \hyperpage{6}
   \item Reversible adiabatic equation for an ideal gas, \hyperpage{32}
   \item Reversible process, \hyperpage{30}
-  \item Reynolds number, \hyperpage{18}
+  \item Reynolds number, \hyperpage{18}, \hyperpage{44}
   \item Robertson inequality, \hyperpage{37}
   \item root-mean-square speed, \hyperpage{19}
   \item Rydberg constant, \hyperpage{23}
@@ -433,11 +440,13 @@
   \item Second law of thermodynamics in terms of entropy, 
 		\hyperpage{33}
   \item Second postulate, \hyperpage{14}
+  \item second viscosity coefficient, \hyperpage{44}
   \item Secular equilibrium, \hyperpage{26}
   \item self-adjoint, \hyperpage{36}
   \item Semi-empirical mass formula, \hyperpage{24}
   \item Sign convention of heat, \hyperpage{31}
   \item Sign convention of work, \hyperpage{31}
+  \item similar, \hyperpage{44}
   \item spacelike, \hyperpage{15}
   \item Specific heat, \hyperpage{19}
   \item specific variables, \hyperpage{30}
@@ -462,6 +471,7 @@
   \item stream function, \hyperpage{43}
   \item streamline, \hyperpage{41}
   \item strength of the vortex tube, \hyperpage{43}
+  \item stress tensor, \hyperpage{43}
   \item superposition, \hyperpage{36}
   \item Superposition principle, \hyperpage{4, 5}
   \item Symmetry of the wave function, \hyperpage{24}