Plumbing Colebrook Friction Factor Calculator
Named Colebrook Darcy—not Fanning—friction on explicit bounded turbulent Re/roughness branch; 80 bisections for implicit Colebrook, no transition/laminar substitution or hydraulic code rating.
Description
Colebrook relates turbulent Darcy friction implicitly to Reynolds number and relative roughness.
Colebrook relates turbulent Darcy friction implicitly to Reynolds number and relative roughness. Solving for inverse square-root friction makes the residual monotone on the chosen bracket.1
The returned values include Modeled darcy friction factors. The How section below explains the calculation, input rules and interpretation.
When to use Plumbing Colebrook Friction Factor Calculator
Use Plumbing Colebrook Friction Factor Calculator when you need to evaluate the supplied records under the calculation and evidence rules below. No laminar/transition substitution, Fanning convention or hydraulic code rating is supplied.
Prepare measured flows, pressures, temperatures or inventories with consistent units. For catalog tools, use independently verified capacities at the stated operating conditions and supply the explicit design demand.
How to use Plumbing Colebrook Friction Factor Calculator and understand its results
- Prepare measured flows, pressures, temperatures or inventories with consistent units. For catalog tools, use independently verified capacities at the stated operating conditions and supply the explicit design demand.
- Enter observedTurbulentReynolds, callerRelativeRoughness using the field table and calculation rules, then run the tool.
- Read modeledDarcyFrictionFactors. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| observedTurbulentReynolds | Observed turbulent reynolds | list of number | Required |
| callerRelativeRoughness | Caller relative roughness | list of number | Required |
Enter aligned nonempty Reynolds numbers 4000–100000000 and relative roughness 0–0.05. Bisect x on [1,20] for 80 iterations for each pair, then return Darcy factors. This is the implicit equation rather than the explicit approximations.
x+2log10(roughness/3.7+2.51x/Re)=0; f=1/x² Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| modeledDarcyFrictionFactors | Modeled darcy friction factors | list of number |
{
"input": {
"observedTurbulentReynolds": [
10000,
100000
],
"callerRelativeRoughness": [
0,
0.001
]
},
"output": {
"modeledDarcyFrictionFactors": [
0.030882950353487683,
0.022174535944515076
]
}
}Limitations and assumptions
No laminar/transition substitution, Fanning convention or hydraulic code rating is supplied.
Numeric inputs, where present, must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Numeric lists are limited to 10,000 entries; string lists to 128 strings of at most 128 characters each. The rules above may impose smaller limits. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use Plumbing Swamee Jain Friction Factor Calculator: The Swamee–Jain approximation estimates the Darcy friction factor for turbulent pipe flow. Darcy and Fanning factors differ by a factor of four. For a complementary task, use Plumbing Haaland Friction Factor Calculator: The Haaland approximation estimates turbulent Darcy friction directly. A Fanning factor uses a different convention.
References
Similar or alternative tools
- Plumbing Swamee Jain Friction Factor Calculator
The Swamee–Jain approximation estimates the Darcy friction factor for turbulent pipe flow. Darcy and Fanning factors differ by a factor of four.
- Plumbing Haaland Friction Factor Calculator
The Haaland approximation estimates turbulent Darcy friction directly. A Fanning factor uses a different convention.