Calculate Gas Viscosity with Sutherland's Law

This Excel spreadsheet calculates the viscosity of gasses with Sutherland's Law. The spreadsheet contains constants suitable for air, but can be used for other gases.

Calculate Gas Viscosity in Excel

William Sutherland was an Australian scientist who studied the temperature-dependence of ideal gases. In 1893, he developed an empirical-theoretical relationship between the temperature and viscosity of an ideal gas.

Essentially, the method uses a known reference viscosity and temperature to find another viscosity at a specified temperature.

Sutherland's formula is

Sutherland's Formula
  • μ is the dynamic viscosity (Pa s or kg m-1 s-1)
  • T is the temperature (K)
  • μref is a reference viscosity (Pa s or kg m-1 s-1)
  • Tref is a reference temperature (K)
  • S is the Sutherland Constant for the gas (K)

The Sutherland Constant is characteristic for the gas. For example, 
  • air at 323 K has a viscosity of 1.716 x 10-5 Pa s, with a Sutherland Constant of 110 K
  • helium at 273K has a viscosity of 1.9 x 10-5 Pa s, with a Sutherland Constant of 79.4 K

The spreadsheet also
  • finds the density of the gas with the Ideal Gas Law
  • calculates the kinematic viscosity by dividing the dynamic viscosity by the gas density

The Ideal Gas Law is given by this formula

Ideal Gas Law

  • R is the Universal Gas Constant (8314.4 J kmol-1 K-1)
  • M is the molecular weight of the gas (kg kmol-1)
  • P is the pressure (Pa)
  • ρ is the density (kg m-3)
The molecular weight of air, for example, is 28.96 kg kmol-1.

Sutherland's Law is accurate for moderate temperatures and pressures, and also describes the viscosity-temperature relationship of gasses at hypersonic speeds.

Download Excel Spreadsheet to Calculate Gas Viscosity with Sutherland's Law

Historical Crude Oil Prices

These two Excel spreadsheets automatically download historical crude oil prices straight into Excel. Both tools are fully automated; the most you do is supply dates and click a button.

Some VBA then downloads the data from a 3rd party website, straight into Excel. After the data is in Excel, you can do whatever you want - visualize price historical, perform economic analysis, correlate oil prices against the cost of other raw materials, and more.

The first spreadsheet downloads Brent oil price data, while the second downloads historical prices for West Texas Intermediate .

West Texas Intermediate Prices

The price of crude oil effects the price of everything we use or consume, including food, fertilizers, gasoline and household electronics. It also influences the price of other industrial chemicals, and accordingly is a major economic factor in the chemical and process industries.

Both spreadsheets are available at my other site, InvestExcel

Download Excel Spreadsheet to Automatically Retrieve Historical Brent Oil Price Data

Download Excel Spreadsheet to Automatically Retrieve Historical WTI Oil Price Data