In this lesson, it will be seen what objectivity and frame invariance imposes on constitutive relations for fluids. This was already seen for ideal fluids and non-ideal fluids will be discussed in this lesson or it can be said that the requirement of objectivity on constitutive relations for viscous fluids will be discussed here. The relation between viscous stress tensor and velocity gradient is also discussed. A general quadratic model for viscous fluids is discussed with some special cases. Examples of Newton’s viscous fluids – air, water are shown. Example for Non-Newtonian Fluid also called Riener-Rivlin fluid.
In this lesson the response is provided to the following question: