Question

Why bernoulli equation is used for two streamlines?

Answer 1

Step-by-step explanation:

Bernoulli's equation is really like an energy conservation equation: if you multiply both sides by the mass flow m˙ (also assumed constant) you get:

12m˙v2+m˙gh+m˙pd=C

The terms are all energy per unit of time. The first one, 12m˙v2, represents translational kinetic energy (per unit of time) of the fluid. But there's no term included for rotational kinetic energy (after all, fluid running through conduits rarely rotate!) So using Bernoulli we assume only translational motion of the fluid.

The equation applies only to inviscid fluids because fluids with significant viscosity experience viscous energy losses, which are not conserved: the energy lost due to viscous friction would have to be supplied, for example by extra pressure, to prevent deceleration (m˙ decreasing).

Answer 2

Answer:

Step-by-step explanation:

Bernoulli's equation is really like an energy conservation equation: if you multiply both sides by the mass flow m˙ (also assumed constant) you get:

12m˙v2+m˙gh+m˙pd=C

The terms are all energy per unit of time. The first one, 12m˙v2, represents translational kinetic energy (per unit of time) of the fluid. But there's no term included for rotational kinetic energy (after all, fluid running through conduits rarely rotate!) So using Bernoulli we assume only translational motion of the fluid.

The equation applies only to inviscid fluids because fluids with significant viscosity experience viscous energy losses, which are not conserved: the energy lost due to viscous friction would have to be supplied, for example by extra pressure, to prevent deceleration (m˙ decreasing).