scientific models are in computer programs rather than mathematical equations
"Scientific computer models" ARE mathematical equations. The physics model in a FPS, the scientific one that simulates air pressure in climate models, or shoots a space probe through a gap in Saturn's rings, they are all using Newton's equations to model the behaviour of an object.
There are generally two types of equations used to build scientific models, whether it be on paper or silicon. The ones that bend to calculus are said to have an "analytical solution" and can be solved with pen and paper, but the majority of problems encountered in nature, engineering, FPS, etc, do not have an analytical solution, they require a supercomputer to crunch the numbers into an answer.
The proper name for "number crunching" is numerical calculus, which is why Babbage called his clockwork computer a "difference engine". In fact the term "computer" comes from the name of the first human job made obsolete by what was arguably the first modern computer, Turing and Co's computer was funded during the height of WW2 because it replaced large numbers of human computers that had the tedious and error prone job of "number crunching" artillery tables.