Continuity Equation

 

Continuity Equation for Area Formula

  • This formula calculates the initial cross-section area of the pipe.

A1=ρ2A2v2v1ρ1     (Continuity Equation for Area

ρ2=A1v1ρ1A2v2

A2=A1v1ρ1ρ2v2

v2=A1v1ρ1ρ2A2

v1=ρ2A2v2A1ρ1

ρ1=ρ2A2v2A1v1

Symbol English Metric
A1 = Initial Area Cross-section in2 mm2
ρ2  (Greek symbol rho) =  Final Cross-section Density lbm/ft3 kg/m3
A2 = Final Area Cross-section in2 mm2
v2 = Final Area Cross-section Velocity ft/sec m/s
v1 = Initial Area Cross-section Velocity ft/sec m/s
ρ1  (Greek symbol rho) =  Initial Area Cross-section Density lbm/ft3 kg/m3

continuity equation 1

The continuity equation, also called conservation of mass equation, is a fundamental principle in fluid dynamics that describes the conservation of mass within a fluid flow.  It states that the rate of change of mass within a control volume is equal to the net rate of mass flow into or out of the control volume.  The continuity equation can also be stated that the change in density over time in a given region is equal to the negative divergence of the mass flux density.  This equation implies that mass is conserved, meaning that the amount of fluid entering or leaving a control volume must be balanced by the change in mass within that volume.

The continuity equation is widely applied in various fields of fluid dynamics, including hydrodynamics, aerodynamics, and fluid flow analysis.  It is a fundamental equation used in conjunction with other equations, such as the Navier-Stokes equations, to analyze and solve fluid flow problems.

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Continuity Equation for Density Formula

  • This formula calculates the initial density of the fluid.

ρ1=ρ2A2v2A1v1     (Continuity Equation for Density)

ρ2=ρ1A1v1A2v2

A2=ρ1A1v1ρ2v2

v2=ρ1A1v1ρ2A2

A1=ρ2A2v2ρ1v1

v1=ρ2A2v2ρ1A1

Symbol English Metric
ρ1  (Greek symbol rho) =  Initial Cross-section Density lbm/ft3 kg/m3
ρ2  (Greek symbol rho) =  Final Area Cross-section Density lbm/ft3 kg/m3
A2 = Final Area Cross-section in2 mm2
v2 = Final Area Cross-section Velocity ft/sec m/s
A1 = Initial Area Cross-section in2 mm2
v1 = Initial Area Cross-section Velocity ft/sec m/s

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Continuity Equation for Mass Formula

  • This formula states that the mass entering a system is equal to the mass leaves the system both at the same rate.

A1v1=A2v2     (Continuity Equation for Mass)

A1=A2v2v1

v1=A2v2A1

A2=A1v1v2

v2=A1v1A2

Symbol English Metric
A1 = Initial Area Cross-section in2 mm2
v1 = Initial Area Cross-section Velocity ft/sec m/s
A2 = Final Area cross-section in2 mm2
v2 = Final Area Cross-section Velocity ft/sec m/s

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Continuity Equation for Velocity Formula

  • This formula calculates the initial velocity in a pipe.

v1=ρ2A2v2A1ρ1     (Continuity Equation for Velocity)

ρ2=v1A1ρ1A2v2

A2=v1A1ρ1ρ2v2

v2=v1A1ρ1ρ2A2

A1=ρ2A2v2v1ρ1

ρ1=ρ2A2v2v1A1

Symbol English Metric
 v1 = Initial Cross-section Velocity ft/sec m/s
ρ2  (Greek symbol rho) =  Final Area Cross-section Density lbm/ft3 kg/m3
A2 = Final Area Cross-section in2 mm2
v2 = Final Area Cross-section Velocity ft/sec m/s
A1 = Initial Area Cross-section in2 mm2
ρ1  (Greek symbol rho) =  Initial Area Cross-section Density lbm/ft3 kg/m3

continuity equation 1