Re: [Boost-users] units use and weird cases....suggestions needed

Subject: Re: [Boost-users] units use and weird cases....suggestions needed
From: Matthias Schabel (boost_at_[hidden])
Date: 2009-09-09 01:18:06

> The problem domain is fluid dynamics so enter the Kv and Cv values.
>
> Technically these are a measure of volumetric flow.  For instance,  
> Kv is defined as:
>
> the flow of water with temperature ranging 5 - 30 oC through a valve  
> in cubic meters per hour (m3/h) with a pressure drop of 1 bar
>
> The problem is that engineers see this as a "unitless" value and  
> treat it as having no units at all.  They use Kv in SI based  
> equations, not m3/s as we'd expect.  Thus all equations being fed to  
> us use Kv as if it were a natural part of the equation.
>
> Most of the time these dimensions do not compute dimensionally  
> anyway but there's rare cases when they do.  I have gotten the  
> engineers (those giving me specs for code I write) to decide on Kv  
> instead of doing both Kv and Cv (it's a basic conversion).

It's a little hard to see where the problem is without a concrete  
example. How about one equation and the corresponding function, with  
ancillary information about the expected units of inputs/output?

Matthias