In the present, every researcher is doing research on the non-Newtonian fluid from the both essential and sensible point of view. These fluids are immediate effects on the processing of polymer, animal blood, liquid crystal, geological flows in the earth mantle. Non-Newtonian fluids were defined by ISSA.
The general equations of Non-Newtonain fluid are highly non-linear and higher order than the Navier-stokes equations. Therefore many analytical and numerical solutions are available of Non-Newtonian fluid on the topic.
Micropolar fluid model is kind of Non-Newtonian fluid which is depend upon a micro-structure and belongs to non-symmetrical stress tensor. Microploar fluid theory was introduced by Eriggen.
Physically, Micropolar fluid may be rigid particles, at random oriented (spherical) elements suspended in a viscous medium where the change of fluid elements is disregarded. Micropolar fluid can perform a better model for animal blood.