Engineering calculators

Two engineering calculators for fluid properties and internal flow, with documented correlations and SI outputs. The air properties calculator returns the density, enthalpy, viscosity, thermal conductivity, specific heats and Prandtl number of dry air at a given temperature and pressure. The pipe flow calculator returns the Reynolds number, flow regime, Darcy friction factor from Colebrook-White, pressure drop, head loss and wall shear stress for a full circular pipe. I use both when setting ECAT boundary conditions, checking Reynolds and Mach similarity for HPT campaigns and teaching fluid mechanics, and both are indexed on the engineering hub.

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Start with your question

Why visitors arrive: You need a quick thermophysical or fluid calculation with traceable correlations.

Your question: What calculators exist, and what assumptions do they use?

You may also be asking

  • How do I size Reynolds or Mach for an experiment?
  • Is there probe uncertainty tooling?
  • Where are the underlying methods documented?

Where to go next

  • Author: Lucas Rey, aerothermal engineer · ORCID · Publications · About
  • Focus: Property and flow calculations for engineering design, experiments and teaching
  • Live tools: Thermophysical properties of dry air (temperature and pressure dependent), and pipe flow pressure drop with the Colebrook friction factor
  • Used in: Viscous flow problems, experimental sizing, CFD boundary-condition checks, and curriculum modules
  • Research context: Correlations underpin publications, project feasibility studies, and instrumentation sizing workflows

Which calculators are available?

The two live calculators and how they pair. Air properties, for dry air by temperature and pressure, returns density ρ and enthalpy h; viscosity μ, ν and conductivity k; specific heats and γ; Prandtl number Pr. It gives the pipe flow calculator the density and viscosity it asks for; pipe flow, for a full circular pipe with Colebrook-White, returns Reynolds number and regime; Darcy friction factor; pressure drop and head loss; wall shear stress. Planned: probe uncertainty, bias propagation for multi-hole pneumatic probes; and heat-exchanger screening, NTU-effectiveness and low-order AM sizing.THE TWO LIVE TOOLS, AND HOW THEY PAIRPLANNED[01]Air propertiesdry air, by temperature and pressureCALCULATED OUTPUTSdensity ρ and enthalpy hviscosity μ, ν and conductivity kspecific heats and γPrandtl number Pr[02]Pipe flowfull circular pipe, Colebrook-WhiteCALCULATED OUTPUTSReynolds number and regimeDarcy friction factorpressure drop and head losswall shear stressdensity andviscosityProbe uncertaintybias propagation formulti-hole pneumatic probesHeat-exchanger screeningNTU-effectiveness andlow-order AM sizing
THE TWO LIVE TOOLS, AND HOW THEY PAIR[01]Air propertiesdry air, by temperature and pressureCALCULATED OUTPUTSdensity ρ and enthalpy hviscosity μ, ν and conductivity kspecific heats and γPrandtl number Pr[02]Pipe flowfull circular pipe, Colebrook-WhiteCALCULATED OUTPUTSReynolds number and regimeDarcy friction factorpressure drop and head losswall shear stressdensity andviscosityPLANNEDProbe uncertaintybias propagation formulti-hole pneumatic probesHeat-exchanger screeningNTU-effectiveness andlow-order AM sizing
THE TWO LIVE TOOLS[01]Air propertiesdry air, by temperature and pressureCALCULATED OUTPUTSdensity ρ and enthalpy hviscosity μ, ν and conductivity kspecific heats and γPrandtl number Prdensity and viscosity[02]Pipe flowfull circular pipe, Colebrook-WhiteCALCULATED OUTPUTSReynolds number and regimeDarcy friction factorpressure drop and head losswall shear stressPLANNEDProbe uncertaintybias propagation for multi-hole pneumatic probesHeat-exchanger screeningNTU-effectiveness and low-order AM sizing
The air properties calculator returns the density and viscosity the pipe flow calculator asks for. Dashed tools are registered and not yet shipped.

Pipe flow calculator

Internal flow · pressure drop

Reynolds number, flow regime, Darcy friction factor from Colebrook-White, pressure drop, head loss and wall shear stress for a full circular pipe. The friction factor was checked against published Moody values before the tool was published, and the page carries that comparison. It pairs with the air properties calculator, which returns the density and viscosity it asks for, and with the viscous flow problem set.

Open calculator

Air properties calculator

Thermophysics · gas dynamics

Returns the thermophysical properties of dry air at a given temperature and pressure. Used in practice for ECAT facility operating-point checks on the HPT deterioration programme, nondimensional similarity work in the fluid mechanics curriculum (developed while teaching in Barcelona), and AM heat-exchanger low-order sizing behind the 2024 Engineering Research Express paper.

Open calculator
Where the two calculators, air properties and pipe flow, are used. Used in: Viscous flow problems, experimental sizing, CFD boundary-condition checks, curriculum modules; Research context: publications, project feasibility studies, instrumentation sizing workflows; I use both when: setting ECAT boundary conditions, teaching fluid mechanics, checking Reynolds and Mach similarity for HPT campaigns.WHERE THE NUMBERS GOTHE TWO CALCULATORSAir propertiesPipe flowproperty and flow calculations fordesign, experiments and teachingUSED INViscous flow problemsexperimental sizingCFD boundary-condition checkscurriculum modulesRESEARCH CONTEXTpublicationsproject feasibility studiesinstrumentation sizing workflowsI USE BOTH WHENsetting ECAT boundary conditionsteaching fluid mechanicschecking Reynolds and Machsimilarity for HPT campaigns
WHERE THE NUMBERS GOUSED INViscous flow problemsexperimental sizingCFD boundary-condition checkscurriculum modulesRESEARCH CONTEXTpublicationsproject feasibility studiesinstrumentation sizing workflowsI USE BOTH WHENsetting ECAT boundary conditionsteaching fluid mechanicschecking Reynolds and Machsimilarity for HPT campaignsTHE TWO CALCULATORSAir propertiesPipe flowproperty and flow calculations fordesign, experiments and teaching
WHERE THE NUMBERS GOTHE TWO CALCULATORSAir propertiesPipe flowproperty and flow calculations fordesign, experiments and teachingUSED INViscous flow problemsexperimental sizingCFD boundary-condition checkscurriculum modulesRESEARCH CONTEXTpublicationsproject feasibility studiesinstrumentation sizing workflowsI USE BOTH WHENsetting ECAT boundary conditionsteaching fluid mechanicschecking Reynolds and Machsimilarity for HPT campaigns
The same two tools answer three different sets of questions on this site: the problems and modules, the research record, and the facility work behind both.

Which calculators are planned?

Two more calculators are planned, for probe uncertainty and for heat-exchanger screening. Each is registered in the engineering catalogue and moves to the list above when it ships.

Planned tools are registered in the engineering catalogue and listed here until shipped, see also the instrumentation theme for probe-uncertainty work.

Workshops, technical review, consulting, research partnerships, teaching: if any of it is close to what you are doing, I would enjoy hearing about it. The professional programmes set out what each one involves.

Contact Lucas Rey

Part of

This page sits within the broader knowledge structure on lucasrey.com:

  • Engineering - Central knowledge platform - tools, curriculum, notes, and research assets.
  • Tools - Interactive calculators and engineering utilities.

Related content from the same research and engineering work:

Part of Engineering

This page is part of the engineering knowledge platform on lucasrey.com.

Engineering knowledge platform

More tools, curriculum, notes, and research from the same body of work:

  • Engineering - Central knowledge platform - tools, curriculum, notes, research, and applied engineering work.
  • Teaching - University STEM support, admissions guidance, and quantitative reasoning - engineering-informed teaching.

Where to go from here

Every paper, practice question and guide on this site is free to read. These are the things worth doing next.

The diagnostic and the practice questions linked above are free and stay free. One-to-one places are limited and taken by application, not by the hour.