Hydraulic Diameter Calculator — Annulus
Hydraulic diameter of an annular gap (pipe-in-pipe, heat-exchanger shell side).
For a concentric annulus the wetted-perimeter algebra collapses to simply D_o − D_i — a result worth memorizing for double-pipe exchangers.
Formula
Hydraulic Diameter Calculator — Annulus is a free annulus hydraulic diameter for process, mechanical and water engineers — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Hydraulic Diameter Calculator — Annulus
Hydraulic diameter of an annular gap (pipe-in-pipe, heat-exchanger shell side). The calculation implements D_h = 4A/P = D_o − D_i (Incropera, Fundamentals of Heat and Mass Transfer, §8.5). For a concentric annulus the wetted-perimeter algebra collapses to simply D_o − D_i — a result worth memorizing for double-pipe exchangers.
How to use Hydraulic Diameter Calculator — Annulus
- 1Enter Outer pipe inner Ø in mm.
- 2Enter Inner pipe outer Ø in mm.
- 3Read Hydraulic diameter, Flow area instantly — no submit button needed.
- 4Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Hydraulic Diameter Calculator — Annulus?
- ✓Implements the standard formula — D_h = 4A/P = D_o − D_i
- ✓Reference cited on-page: Incropera, Fundamentals of Heat and Mass Transfer, §8.5
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Live worked example: the substitution recomputes from your numbers
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Hydraulic Diameter Calculator — Annulus use?+
It computes D_h = 4A/P = D_o − D_i, per Incropera, Fundamentals of Heat and Mass Transfer, §8.5. The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
For a concentric annulus the wetted-perimeter algebra collapses to simply D_o − D_i — a result worth memorizing for double-pipe exchangers.
Does this work for any fluid?+
Yes — density and viscosity are inputs (with common fluids suggested in the field hints), so the same physics applies to water, oils, gases and process fluids. Compute always runs in SI internally, so unit mix-ups can't corrupt the result.
Is the Hydraulic Diameter Calculator — Annulus free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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