## Related Terms

### ACCELERATION

The rate of change of velocity, as a function of time. Expressed in m/s2.

### ANEMOMETER

An instrument for measuring the velocity of a fluid.

### TERMINAL VELOCITY

The highest sustained air stream velocity existing in the mixed air path at the end of the throw.

### PARTICLE EROSION

Occurs when fluid-entrained particles moving at high velocity pass through orifices or impinge on metering surfaces or sharp angle turns.

### CENTRIFUGAL PUMP

Pump which produces fluid velocity and converts it to pressure head.

### PARTICLE IMPINGEMENT EROSION

A particulate wear process where high velocity, fluid- entrained particles are directed at target surfaces.

### SHEAR STRESS

Frictional force overcome in sliding one layer of fluid along another, as in any fluid flow. The shear stress of a petroleum oil or other Newtonian fluid at a given temperature varies directly with shear rate (velocity). The ratio between shear stress and shear rate is constant; this ratio is termed viscosity of a Newtonian fluid, the greater the shear stress as a function of rate of shear. In a non-Newtonian fluid, such as a grease or a polymer-containing oil (e.g. multi-grade oil) - shear stress is not proportional to the rate of shear. A non-Newtonian fluid may be said to have an apparent viscosity, a viscosity that holds only for the shear rate (and temperature) at which the viscosity is determined.

### SLIP VELOCITY

The phase velocity difference between two phases.

### MULTIPHASE FLOW VELOCITY

The flow velocity of a multiphase flow. It may also be defined by the relationship (Multiphase volume flow rate / Pipe cross-section).

### PHASE VELOCITY

The velocity of one phase of a multiphase flow at a cross-section of a conduit. It may also be defined by the relationship (Superficial phase velocity * Phase area fraction).