Ideal fluid: A fluid, which is incompressible and is having no viscosity, is known as an ideal fluid. Ideal fluid is only an imaginary fluid as all the fluids, which exist, have some viscosity.
Real fluid: A fluid, which possesses viscosity, is known as real fluid. All the fluids, in actual practice, are real fluids.
Newtonian fluid: A real fluid, in which the shear stress is directly, proportional to the rate of shear strain, is known as a newtonian fluid.
Continuity equation for steady flow: For any type of fluid the continuity equation must be satisfy.
(ρu)+(ρv)+(ρw)=0 If the fluid is incompressible and steady flow than continuity equation:
++=0