AHA! I started SimScale life using English units.
I thought, how hard can it be to simply convert them properly in the SimScale interface?
It turned out, that answer was, very hard, and I know they tried.
My solution was to forget all about English units, I advise you not to question this but to adopt only SI units here at SimScale (even in your CAD files…)
You should be able to search and see my forum posts about this (~1 year ago) …
I know you will get there on your results, don’t give up, good luck…
It is fortunate that you have real life results to look at… 
Dale