3.5 Equation of continuity

The equation of continuity works under the assumption that the flow in will equal the flow out. This can be useful to solve for many properties of the fluid and its motion :

Flow in = Flow out

Using the known properties of a fluid in one condition, we can use the continuity equation to solve for the properties of the same fluid under other conditions.

This can be expressed in many ways, for example: A1V1 =A2V2. The equation of continuity applies to any incompressible fluid. Since the fluid cannot be compressed (ρ= constant), the amount of fluid which flows into a surface must equal the amount flowing out of the surface.

The Equation of Continuity in compressible flow can be expressed as:

m = ρ_i1 v_i1 A_i1 + ρ_i2 v_i2 A_i2 +...+ ρ_in v_in A_in

    = ρ_o1 v_o1 A_o1 + ρ_o2 v_o2 A_o2 +...+ ρ_out v_out A_out           

where                     

m = mass flow rate (kg/s)

ρ = density (kg/m³)

v = speed (m/s)

A = area (m²)

Next bernoulli's equation http://fluidbloggroup3.blogspot.com/2014/05/fluid-bernoullis-equation.html