cape.units: Unit Conversion Module

CAPE includes this unit-conversion module to interpret various units for inputs and post-processing. Many CFD solvers, and some trajectory tools that are used to provide flight conditions, expect imperial units, which can be challenging to interpret and difficult to use in complications.

The main function of this module is called mks(), which takes a string as input and tries to convert it to a numerical output as multiple of meters, kilograms, and seconds (and Kelvins and amperes or several other fundamental units as needed). For example it will return 0.0254 if the input is "inch", which is the length of an inch in meters.

>>> mks("inch")
0.0254

This function also takes more complexly defined units using exponents, multiples and ratios, and SI prefixes. For example, this converts thousand pounds per square foot to the appropriate mks unit, which is Pascals.

>>> mks("klbf/ft^2")
4.7880e+04

The module also contains several simple float values, such as psf for the value of pounds per square feet in Pascals. There is a dict called units_dict that contains a full dictionary of recognized unit names.

>>> units_dict['psf']
47.88025903135141

cape.units.mks(unit_lbl)

Convert a string for arbitrary nits to numerical MKS value

Call:

>>> val = mks(unit_lbl)

Examples:

>>> mks("kg")
1.0
>>> mks("lbf/ft^2")
47.880

Inputs:

unit_lbl: str | unicode

String describing units

Outputs:

val: float

Units converted to numerical value assuming MKS system

Versions:

• 2018-04-12 @dalle: Version 1.0