Engineering Tool Hub/Workflows/Internal Flow

ENGINEERING WORKFLOW / 002

Internal Flow Workflow

Enter the pipe or duct system once. Abecator carries the same geometry, fluid and flow state through hydraulic diameter, Reynolds number, Darcy friction factor, straight-run loss, K-factor losses, elevation head and pump/fan pressure requirement.

Pipe & duct systemsDarcy–WeisbachMajor + minor lossesRuns locally

01 — FLUID & FLOW

Define the bulk flow state.

Start from volumetric flow, mass flow or mean velocity. The workflow converts the other two consistently using the selected area and density.

Fluid preset Flow input basis Volumetric flow ratem³/sThe workflow calculates mean bulk velocity from the selected cross-sectional area. Density ρkg/m³ Dynamic viscosity μPa·s

02 — FLOW PASSAGE

Define the hydraulic geometry.

Circular and rectangular sections are converted automatically. Use custom area and hydraulic diameter for more general ducts.

Geometry Pipe diameter Dm Straight-run length Lm Absolute roughness εmUse a roughness value appropriate to the actual material and condition. The default is only an example engineering value.

03 — LOCAL LOSSES & SYSTEM HEAD

Add fittings, elevation and efficiency.

Combine bends, valves, contractions and other local losses into a total K based on the same bulk reference velocity.

Total minor-loss coefficient ΣK—Keep K definitions consistent with the bulk velocity used by this workflow. Outlet elevation − inlet elevationmPositive means the outlet is above the inlet and increases the required pressure rise. Pump / fan efficiency%Used only for the approximate shaft-power estimate.

All engineering inputs and calculations stay in your browser. Abecator analytics record only anonymous interaction events, not your flow rates, dimensions or pressure values.

CONSOLIDATED SYSTEM CHECK

Internal-flow summary

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POSITIVE PUMP / FAN PRESSURE REQUIREMENT—

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Volume flow—

Mass flow—

Mean velocity—

Flow area—

Hydraulic diameter—

Reynolds number—

Flow regime—

Relative roughness ε/Dh—

Darcy friction factor—

Friction model—

Dynamic pressure—

Straight-run loss—

Minor / K loss—

Total friction + local loss—

Elevation pressure term—

Net required head—

Straight-run dp/dx—

Equivalent friction K—

Major-loss share

Minor-loss share

Hydraulic power—

Estimated shaft power—

Mean transit time L/V—

Pipe / duct flow calculatorInspect flow rate, velocity and area independently. Hydraulic diameter calculatorCheck non-circular passage geometry separately. Friction factor / Moody calculatorCompare friction-factor behavior and roughness effects. Minor-loss K calculatorInspect local fitting losses before combining them. Pressure-drop calculatorRun a focused Darcy–Weisbach pressure-loss check.

WHAT THIS WORKFLOW DOES

It turns a collection of pipe-flow formulas into one consistent system calculation.

The same area and hydraulic diameter determine velocity and Reynolds number. That Reynolds number and roughness determine the Darcy friction factor. Straight-run and local losses use the same dynamic pressure before elevation head is added to obtain the net pressure requirement.

The workflow is intended as an engineering benchmark for CFD, duct, manifold, piping and ventilation studies—not as a substitute for project-specific codes, manufacturer curves or compressible network solvers.

Bulk flow. Q, ṁ and V are tied together through density and flow area.

Hydraulic scale. Re = ρVDh/μ and ε/Dh establish the friction-factor regime.

Pressure losses. Darcy–Weisbach handles straight-run loss while ΣK handles fittings and local geometry.

System requirement. Friction + local losses + ρgΔz give the net pressure rise before efficiency is applied to power.

WHEN THE SIMPLE SYSTEM MODEL IS NOT ENOUGH

Use the workflow as a benchmark, then investigate the CFD physics.

Strong separation, swirl, developing flow, compressibility, complex manifolds and uncertain K values can make a one-dimensional pressure-loss estimate insufficient.

TECHNICAL CASE

Internal Flow Workflow

Define the bulk flow state.

Define the hydraulic geometry.

Add fittings, elevation and efficiency.

It turns a collection of pipe-flow formulas into one consistent system calculation.

Use the workflow as a benchmark, then investigate the CFD physics.

CFD pressure drop does not match

Mass imbalance in CFD

Internal-flow & pressure-drop CFD