question_answer

Bernoulli?s theorem holds for incompressible, non-viscous fluids. How is this relationship changed when the viscosity of the fluid is not negligible?

Answer:

                If the viscosity of the fluid is not negligible, a part of the mechanical energy of the fluid is spent in doing work against forces of viscosity. So the total energy:\[P+\rho gh+\frac{1}{2}\rho {{\upsilon }^{2}}\]of the fluid goes on decreasing along the direction of flow of the fluid.