Bernoulli Equation

Several facts concerning the flow of liquids and gases can be analyzed by just applying the Bernoulli equation. Bernoulli equation determines the relationship between flow rate and pressure difference for ideal fluid flow assuming that the changes in elevation, work and heat transfer are negligible. Bernoulli equation is given as:

Bernoulli Equation

Because of its ease, the Bernoulli equation is an excellent point to initiate, however it may not give an exact response for many situations. Undoubtedly, it can make available a first estimate of parameter values. After incorporating viscous effects in the simple Bernoulli equation, the resulting equation is referred to as “energy equation”.

Bernoulli equation is based upon following assumptions:

  • Fluid is incompressible and nonviscous.
  • No energy is vanished because of friction caused between the liquid and the pipe wall.
  • No heat energy gets transferred across the boundaries of the pipe to the liquid as either a heat gain or loss.
  • No pumps are present in the section of pipe under consideration.
  • Flow of liquid is laminar and steady and is alongside the length of the stream.
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It is an application of the Law of Energy Conservation, stating that the sum of all forms of energy in a moving fluid stream (height, kinetic, and pressure) must remain the same. Relevant to calculations of pressure drop and pressure recovery across restrictions such as venturi tubes, orifice plates, etc.