Momentum and Fluid Transport
- Momentum transport (Fluid Transport) is based on the principle of conservation of momentum (Newton’s second law of motion).
- The property we follow is the flux of momentum (quantity of momentum transferred per unit time per area, τyz)
- We use a transport law to relate the flux to the gradient of momentum (Newton’s Law of Viscosity)
- We combine momentum conservation with the transport law to calculate velocity fields
The Navier-Stokes equation is the most used form of momentum balance:
The first line represents the conservation of momentum—basically, the Newton's second law—in terms of fluid velocity vector u and pressure p. The second line represents the conservation of mass. The body force f is frequently absent, and the remaining parameters—fluid density and viscosity—are often constant. In spite of their simple form, the Navier-Stokes equations are capable of producing an astounding variety of fluid flows.
The analysis of fluid transport is fundamental in the design and control of a industrial process. Different fluids have different resistances to flow, this property is known as a viscocity.
The conservation of momentum says that the sum of momentum of all atoms before the collision must be equal that after the collision.