added minor file and corrections

Introduction to fluid dynamics.md

@@ -23,7 +23,9 @@ Three ways flows can be be split:
 ### (Un)Steady flows
 Steady: flow variables do not depend on time.
 
-d/dt = 0
+Partial derivatives with respect to time are null.
+
+drond/drondt = 0
 
 ### (In)compressible flows
 A flox can be considered incompressible is the Mach number is low enough:

Material derivative and transport theorem.md

@@ -0,0 +1,3 @@
+# Material derivative and transport theorem
+
+Voir pdf résumé