# fluid mechanics 3

## 29 terms

### Lagrangian

All fluid particles are followed and their location, velocity, density, pressure, etc. is monitored as they travel in time.

### Eulerian

When fixed points in space are identified and the velocity, density, pressure, etc. are found at those fixed points in space as functions of time.

### streamline

An imaginary line in the flow that is everywhere parallel to the local velocity vectors

### streakline

An instantaneous line composed of all particles originating from a given point in the flow field.

### pathline

The locus of points traversed by a single particle as it travels through a flow field.

For __________(time independent), streamlines, streaklines, and pathlines coincide.

### solid surfaces

always streamlines

### streamlines

Fluid particles cannot cross ____________

### differential equations

hold at a point in a flow field

### integral equations

hold for some volume of fluid

### (δρ/δt)+(δ/δx)(ρu)+(δ/δy)(ρv)+(δ/δz)(ρw)=0

differential form of conservation of mass

### (δ/δt)∫ρdV+∫ρV⋅dA=0

integral form of conservation of mass

### mass flow rate

mass per unit time passing a point

### lbm/sec, kg/sec

units for mass flow rate

### mass flux

mass per unit time passing a unit area

### lbm/secft², kg/secm²

units for mass flux

mass flow rate

mass flux

### uniform flow

when velocity and other fluid properties are constant over the cross-sectional area

### (Dv/Dt)=(-1/ρ)(δp/δy)+fy

Euler equation in y-direction

### (DV/Dt)=(-1/ρ)∇P+f

Euler's equations in vector form

### DV/Dt

total rate of change of momentum

### δV/δt

temporal rate of change of momentum

### (V⋅∇)V

convective rate of change (or convective acceleration) of momentum

surface force

body force

### one-dimensional flow

velocity depends on only one spatial variable

### two-dimensional flow

velocity depends on only two spatial variables