# Velocity of fluid in annulus

## Input(s)

$Q$: Flow rate $(\mathrm{gpm})$

$D_{o}$: Open Hole Diameter (in.)

$D_{p}$: Outside Diameter of Pipe (in.)

## Output(s)

$v_{a}$: Velocity of Fluid in Annulus (ft/s)

## Formula(s)

$v_{a}=\frac{Q}{2.448 *\left(D_{o}^{2}-D_{p}^{2}\right)}$## Reference(s)

Samuel. E Robello. 501 Solved Problems and Calculations for Drilling Operations. Sigma Quadrant. 2015. Houston, Texas, Page: 321.