Technical writing in mathematics and physics generally follows its own rules in regard to the use of punctuation, etc. I would suggest looking at textbooks on the subjects and see how information like this is presented. I think unnecessary commas should be avoided, and I believe, although I am not even remotely an expert on the subject, that your sentence would not be punctuated at all:
The maximum acceleration a_max is calculated by assuming a height h.
Here is a similar authentic example from the web:
It should be noted that if the maximum acceleration A_max (T) and the maximum velocity V_max (T) were not dependent on the temperature, [...]
I agree that the rules of commas do not depend on articles. There are plenty of resources on the usage of commas, such as this one
, which I would recommend taking a look at.
(Note the correct spelling of "height".)