The Bernoulli equation
The Bernoulli equation is the first line integral of the equation of motion. The equation can take various forms, depending on the particular kinematical or dynamical assumptions relating to the…
The perfect fluid
The fundamental property which distinguishes a fluid from other continuous media is that it cannot be in equilibrium in the presence of tangential stresses. If any infinitesimal tangential stress acts…
Mechanical equilibrium of fluids
This equation places a restriction on the body forces. Mechanical equilibrium can exist only if the body force field satisfies the above equation. It is clear that this condition can…
The balance of entropy
The entropy is a thermodynamic variable of state; an extensive quantity. It cannot be experienced directly; as a derived variable entropy represents a measure of the irreversibility of a change…
The principle of conservation of energy
Any material system is characterized by its energy content. Energy occupies a position of distinction amongst the other extensive variables. Whatever interaction occurs between a material system and its surroundings,…
The balance of kinetic energy
Let Ek denote the kinetic energy of a material volume: Although the kinetic energy is an extensive variable it is not a quantity which is conserved. Thus the balance equation of kinetic…
The balance of angular momentum
The principle of conservation of angular momentum belongs to the axioms of mechanics. In spite of its general validity it has been largely neglected in textbooks written for petroleum engineers.…
The balance of momentum
Newton’s second law of motion is perhaps the most important statement in the field of dynamics. As is well-known this states that the rate of change of the momentum of a body…
