dP Pressure Drop
Formulae
Here's some background data on the formulae being used by pressure drop. Since the flow can have two states it requires to have two sets of formulas.
- Laminar Flow (Reynolds < 2320)
- Turbulent Flow (Reynolds >= 2320)
- There is also a page which contains tables with Equivalent lengths and Surface roughness values
Laminar Flow (Reynolds < 2320) |
|||
| Name | Symbol | Formula | Unit |
| specific gravity | g | 9.81 | m/s |
| pipe length | L | - | m |
| inner diameter | Di | - | mm |
| pipe area | A | 0.25 x Di | mm |
| average velocity | v | flow/A | m/s |
| Reynolds | Re |
 |
- |
| eq.length | Leq |
 |
m |
| friction factor | F | 64/Re | - |
| relative roughness surface | k/Di | n.a. | - |
| friction of pipe | Kw(pipe) | F x L / Di | - |
| friction appendages | Kw (app) | F x Leq / Di | - |
| pipe volume | V | A x L | liter |
| residence time / transportation lag | t | L / v | sec |
| power loss in fluid | P |
 |
 |
| pressure drop in pipe |
 |
 |
bar |
Turbulent Flow (Reynolds >= 2320) |
|||
| Name | Symbol | Formula | Unit |
| specific gravity | g | 9.81 | m/s |
| pipe length | L | - | m |
| inner diameter | Di | - | mm |
| pipe area | A | 0.25 x Di | mm |
| average velocity | v | flow/A | m/s |
| Reynolds | Re |
|
- |
| eq.length | Leq |
|
m |
| friction factor (iterative algorithm of Colebrook-White) |
 |
 |
- |
| relative roughness surface | k/Di | n.a. | - |
| friction of pipe | Kw(pipe) | F x L / Di | - |
| friction appendages | Kw (app) | F x Leq / Di | - |
| pipe volume | V | A x L | liter |
| residence time / transportation lag | t | L / v | sec |
| power loss in fluid | P |
|
|
| pressure drop in pipe |
|
|
bar |
Go with the Flow
dP will automatically switch from Laminar Flow Mode to Turbulent Flow Mode depending on the Reynolds value